Effects of oestrogen treatment on serum gonadotrophin bioactivity, immunoreactivity and isohormone distribution, and on immunoreactive inhibin levels, in prostatic cancer patients

OBJECTIVE AND DESIGN No data are available on effects of long-term exposure to oestrogen on bioactivity of gonadotrophins in men. We studied the effects of a 6-month oestrogen therapy on serum FSH and LH bioactivity (B), immunoreactivity (I) and isohormone distribution, and on serum l-inhibin levels, in patients with prostatic carcinoma. PATIENTS Eleven men with advanced prostatic cancer were studied, each receiving 160 mg of polyoestradiol phosphate (Estradurin) once a month intramuscularly for 6 months. MEASUREMENTS Serum samples were collected before, and after 2 and 6 months of oestrogen treatment. Serum B-and l-FSH levels were measured by immature rat granulosa cell bioassay and immunofluorometric (IFMA, Delfia) assay, respectively, and those of B- and I-LH by mouse interstitial cell bioassay and IFMA, respectively. Serum oestradiol (E₂) concentrations were measured by IFMA assay, and serum testosterone (T) and inhibin levels by radioimmunoassay. Isoelectric focusing was used for fractionation of the FSH and LH isoforms. RESULTS The pretreatment levels of B-FSH and I-FSH were 84.7 ± 21.6 and 11.4 ± 3.2 IU/I (mean ± SEM), respectively, and the B/I ratio of FSH was 8.3 ± 1.0. The pretreatment levels of B-LH and I-LH were 23.5 ± 3.2 and 10.1 ± 2.3 IU/I, respectively, and the B/I ratio was 3.0 ± 0.4. After 6 months of oestrogen therapy, B-FSH and I-FSH decreased to 37.5±8.1 (P< 0.05)and 1.3 ± 0.3 IU/I(P<0.01), respectively, but the B/I ratio of FSH increased to 28.5 ±4.2 (P<0.05). B- and I-LH levels decreased in 6 months to 7.4 ± 0.9 and 2.3 ± 0.5 IU/I (P<0.01), respectively, but no change was found in the B/I ratio of LH. Serum T levels decreased from 19.0 ± 2.6 to 2.7± 0.9 nmol/l (P<0.01) during the 6-month treatment, and the respective E₂ levels increased from 0.2± 0.01 to 4.4±0.5 nmol/l (P<0.01). Serum l-inhibin levels were analysed from eight patients. The levels at 0,2 and 6 months were 0 81 ± 0.09,0.50 ± 0.03 and 0.54 ± 0.01 μ/l, respectively. Gonadotrophins in the pretreatment and 6-month samples of four patients were analysed by Isoelectric focusing. In FSH of all subjects, and in LH of three subjects, a shift from acidic to more basic isoforms occurred after oestrogen therapy. This is in keeping with the increase of the B/l ratio of FSH. With LH, the isoform shift occurred between fractions with similar B/I ratios, and hence there was no shift in the overall B/I ratio. CONCLUSIONS Oestrogen therapy of men suppressed bioactive and immunoreactive levels of gonadotrophins. The B/I ratio of FSH increased, and this increase was associated with a shift in the isohormone profile to more basic forms. In contrast, no change occurred in the B/I ratio of LH, even though changes in the isohormone profile were observed. Hence, not all changes in the isohormone distribution of gonadotrophins result in changes of the intrinsic in-vitro bioactivity.     

Growth hormone dose regimens in adult GH deficiency: effects on biochemical growth markers and metabolic parameters

OBJECTIVE We examined the effects of different doses of GH on insulin-like growth factor I (IGF-I), IGF binding protein 3 (IGFBP-3), body composition, energy expenditure, and various metabolites in GH deficient adults, in order to approach a metabolically appropriate GH dosage in young GH deficient adults. DESIGN Ten GH deficient patients (age 21–43) were studied after 4 weeks without GH followed by three consecutive 4-week periods, where the patients received in a fixed order GH 1,2 and 4 IU/m² s.c. per day. At the end of each period the patients were hospitalized for a 24-hour examination. RESULTS Mean 24-hour levels of GH (mIU/l) were 2.7±0.3 (0 GH), 7 2±0.9 (1), 10.8±1.5 (2) and 18.9±2.7 (4 IU/m²) (mean ±SEM) (P<0.01). Likewise, IGF-I levels increased dose dependently from 61 ± 21 to 206 ± 65, 260 ± 70 and 468 ± 171 /μg/l (P < 0 05); serum IGF-I in an age and sex matched control group was 248 ± 25 /μg/l. Corresponding serum IGFBP-3 levels also increased from 1860 ±239 to 3261 ±379, 3762 ±434 and 4384 ±652 /μg/l (P = 001) respectively. Significant increases in diurnal serum insulin levels after 4 IU/m² were recorded, whereas plasma glucose levels remained unchanged. Lipid intermediates increased dose independently during GH administration. GH caused a significant increase in resting energy expenditure, whereas the respiratory exchange ratio was unaltered. Fat mass was increased without GH therapy and decreased during the study. Four patients made complaints during 4 IU/m² GH administration, probably related to GH induced fluid retention. CONCLUSION Based primarily on IGF-I and IGFBP-3 levels our data suggest that a GH replacement dose in young GH deficient adults in the order of 1–2 IU/m² per day is adequate. This is a relatively low dose as compared to dose regimens in children and adolescents.     

Efficacy of low dose purified FSH in ovulation induction following pituitary desensitization in polycystic ovarian syndrome

OBJECTIVES We evaluated the efficacy of ovulation Induction using purified FSH in either low dose or conventional dosage in patients with polycystic ovarian syndrome. We assessed whether gonadotropin measurement by radioimmunoassay or immunoradiometric assay is a better indicator of whether pituitary desensitization with a GnRH agonist (Zoladex) has occurred. DESIGN Two different protocols were used. Pituitary desensitization was carried out with a GnRH agonist (Zoladex, ICI Pharmaceuticals UK). The patients were then randomized into one of two treatment groups. Conventional dose protocol: Patients commenced with a daily FSH (Metrodin, Serono Laboratories Ltd, UK) dose of 75 units for at least 7 days. The FSH dose was then increased, if necessary, based on ultrasound scans and plasma oestradiol (E²) levels in 75-unit increments. Low dose protocol: The same protocol was used except that the starting dose of FSH was 37.5 units daily with increments of 37.5 units. RESULTS Low dose protocol (six patients, six cycles). There was a high incidence of multiple follicular development (10.3 ± 5.6 (SD) follicles, 5.0 ± 3.8 follicles < 14 mm in diameter). Three cycles resulted in ovulation, one was anovulatory and two patients underwent gamete intrafallopian transfer due to multiple follicular development. Conventional dose protocol (seven patients, eight cycles). Again there was multiple follicular development (10.1 ± 8.6 follicles, 2.0 ± 2.3>14 mm). Three cycles were ovulatory, one anovulatory, three abandoned due to multiple follicular development and one underwent gamete intrafallopian transfer with the development of severe hyperstimulation necessitating steroid therapy. There was no difference between the two protocols in the number of days of FSH administration (low dose protocol 26 ± 6.5, conventional dose protocol 23 ± 8.1 days), the total number of units of FSH given per patient was 2844 ± 1816 vs 2635 ± 1726. The peak E² level (pmol/l) during FSH treatment was 3193 ± 662 vs 2389 ± 3099 and the rate of Increase in the FSH dose in ampoules of Metrodin per day was 0.058 ± 0.03 vs 0.057 ± 0.03. All patients were‘downregulated’ (E²<70 pmol/l) prior to ovulation induction. However, gonadotrophin levels (IU/I) were 4.3 ± 1.5 (LH) and 2.8 ± 1.2 (FSH) by radioimmunoassay and LH was unchanged throughout FSH treatment whereas LH measured by immunoradiometric assay was <1.0 IU/I prior to ovulation induction and remained so throughout. The mean LH radioimmunoassay to immunoradiometric assay ratio was 6.2 ± 2.1. CONCLUSIONS We conclude that regardless of the starting dose the use of pure FSH in patients with polycystic ovarian syndrome whose LH has been completely down regulated may be associated with multiple follicular development and a poor outcome. LH measured by radioimmunoassay is not a good indicator of whether pituitary densensitization has occurred but LH measured by immunoradiometric assay appears to be. These results strongly suggest that a basic minimum amount of LH is necessary for normal ovulatory development.     

THE EFFECTS OF PROLONGED ADMINISTRATION OF D-SER(TBU) 6-LH-RH-EA10 (HOE 766) IN SUBJECTS WITH HYPOGONADOTROPHIC HYPOGONADISM

Nine patients with hypogonadotrophic hypogonadism (five due to isolated gonadotrophin deficiency and four due to craniopharyngioma) were treated with daily subcutaneous injections of a long acting LHRH analogue, Hoe 766. Therapy was continued for between 27 and 38 weeks and doses varied between 1–25 and 5 μg per day. At monthly intervals patients were assessed by their LH and FSH response to 100 μg of LHRH and by second hourly sampling for LH, FSH and testosterone for the 24 hours after their Hoe 766 dose. Regardless of the diagnosis or the dose of Hoe 766 the LH response to Hoe 766 and to LHRH deteriorated with increasing duration of therapy. Plasma FSH values became low after only 1 week of therapy and failed to improve. Peak plasma testosterone during therapy correlated with peak plasma LH regardless of the duration of treatment (r = 0±43, P < 0±05, n = 22). Peak plasma LH on LHRH stimulation tests correlated with peak plasma LH on Hoe 766 24 hour studies independently of the length of treatment or the dose of Hoe 766 (r=0±62, P < 0±01, n = 18). In this group of patients peak plasma LH on LHRH stimulation tests did not correlate with basal plasma LH. Throughout the study in all patients testosterone was subnormal at 08.00 h. If testosterone rose after Hoe 766 it did so within the first 12 hours following the injection and had returned to baseline levels by 08.00 h the following day. It is concluded that prolonged daily administration of Hoe 766 within the dose range studied leads to loss of pituitary LH and FSH responses to both Hoe 766 and LHRH. Our results suggest that the loss of LH responsiveness is not due to testosterone feedback inhibition or selective resistance to Hoe 766, but may be explained by depletion of gonadotrophin stores in the pituitary gland.     

Impact of 2 weeks high dose growth hormone treatment on basal and insulin stimulated substrate metabolism in humans

OBJECTIVE Short-term, high dose growth hormone (GH) treatment has been advocated in many catabolic disease states. It is likely that some of the anabolic effects of GH are mediated through activation of lipolysis, but the metabolic impact of therapeutically relevant GH exposure is not known in detail. The present study was accordingly designed to assess the effects of such GH exposure on basal and insulin stimulated intermediary metabolism. DESIGN, PATIENTS AND MEASUREMENTS Six healthy young females were examined following daily injections of GH (12 IU/day) or saline for 2 weeks in a placebo controlled design. Each study consisted of a 3 hour basal period and a 2 hour hyperinsulinaemic euglycaemic clamp. RESULTS GH treatment caused (1) increased levels of IGF-I (382 ± 46 vs 294 ± 22 /μg/l, P < 0 05) and (2) increased basal values of free fatty acids (714 ±40 (GH) vs 634 ±64 (placebo) μmol/l, P<0 05), 3-hydroxybutyrate (118 3 ± 42 8 (GH) vs 57 7 ± 21 6 (placebo) μmol/l, P < 0 05), glycerol (54–3 ±8–2 (GH) vs 41–4 ±8–4 (placebo) μmol/l, P<0 05) and forearm uptake of 3-hydroxybutyrate, together with increments of plasma glucose (5 28 ±0–11 (GH) vs 4 87±0 16 (placebo) mmol/l, P<0 05). Basal forearm uptake of glucose, isotopically determined glucose turnover and serum levels of GH, insulin and C-peptide were unaltered. During the clamp GH treatment was associated with (1) a 40% decrease in the administered amount of glucose (M-value) (P<0 05) and (2) a 70% decrease in forearm glucose uptake (P<0 05). Indirect calorimetry revealed a 15% increase in resting energy expenditure (P<0 05) and a decreased basal respiratory exchange ratio (0 75 (GH) vs 0 80 (placebo), P<0 05), presumably reflecting increased lipid oxidation. CONCLUSIONS Administration of GH in a therapeutic dose for 2 weeks, despite apparently normal daytime levels of major metabolic hormones, induces significant increases in circulating lipid fuel substrates, increased energy expenditure and lipid oxidation, together with insulin resistance. Such effects should be considered when applying GH treatment schedules clinically.     

The effect of recombinant IGF-I on anterior pituitary function in healthy volunteers

OBJECTIVE Insulin-like growth factor-I is the mediator of many of the actions of GH and is a potent metabolic regulator. Recombinant IGF-I (rhIGF-I) is of potential value in the treatment of syndromes associated with either GH or insulin resistance. This study was designed to assess the effects of subcutaneous (s.c.) rhIGF-I on anterior pituitary function. DESIGN Double-blind, placebo controlled, randomized cross-over study. The interval between investigations was 2 weeks. SUBJECTS Twelve normal volunteers received on one occasion a single S.C. dose of 40 μg/kg rhIGF-I and on the other, placebo. MEASUREMENTS Circulating levels were measured, over 24 hours, of GH, LH, FSH, PRL, TSH, cortisol, ACTH, glucose, IGF-I, IGF-II, Insulin, C-peptide; IGF binding proteins by Western ligand blotting; total IGF bioactivity using FRTL-5 thyroid cells; and glucose by the glucose oxidase method. RESULTS Recombinant IGF-I Increased AUC for plasma IGF-I, measured by radioimmunoassay (rhIGF-I mean 7065 ± SEM 33 vs 3895 ± 204 μg/l, P < 0·0001) and IGF bioactivity (22·5 ± 3·4 vs 14·2 ± 1·8 U/ml, P < 0·001) but plasma IGF-II fell (9308 ± 403 vs 11052 ± 451 μg/l, P < 0·0001). There was no biochemical or clinical evidence of hypoglycaemia and no difference in mean glucose levels. No difference existed in AUC for GH, LH, FSH, ACTH and cortisol between rhIGF-I and placebo; additionally, pulse number and amplitude for GH and LH were unaffected. TSH fell following rhIGF-I (33·0 ± 3·36 vs 42·5 ± 5·98 mU h/l, P= 0·01). Both mean plasma C-peptlde (0·73 ± 0 06 vs 0·91 ± 0±05 nmol/l, P= 0·03), and insulin (10·81 ± 1·02 vs 15·36 ± 1·18 mU/l, P= 0·03) were lower following rhIGF-I. There was no change In IGFBPs. CONCLUSION A single injection of 40 μg/kg of subcutaneous rhIGF-I does not cause hypoglycaemia. IGF bioactivity was increased without inhibition of GH secretion. The only change observed in anterior pituitary function was a fall in plasma TSH.     

GH substitution does not alter the pulsatile pattern of LH in amenorrhoeic growth hormone deficient women

OBJECTIVE: GH substitution in GH-deficient (GHD) children promotes pubertal development. In some GHD women, secondary amenorrhoea occurs after discontinuation of GH treatment. This study was designed to investigate whether GH substitution directly influences the GnRH pulse generator. For this reason, the pulsatile release of LH was studied in amenorrhoeic GHD women before and during GH substitution. DESIGN: GH deficiency was confirmed by an insulin tolerance test. During a 24-h period, blood samples were drawn every 10 min for determination of LH, FSH and GH levels. Oestradiol and IGF-1 were determined at 1000 h and 2200 h. After the first test day, patients started with GH substitution, 0.25 IU/kg/week. During month 6 of GH treatment, the 24 h blood sampling was repeated. SUBJECTS: Ten amenorrhoeic GH-deficient women participated in the trial. All were diagnosed as GH deficient during childhood or adolescence. Eight of them had been treated with GH during childhood. Seven women suffered from primary amenorrhoea and three from secondary amenorrhoea. Six women were started with GH substitution after the first test day (according to randomization in a larger study). MEASUREMENTS: LH and GH were determined every 10 min and FSH every 60 min. LH pulse detection was conducted using a validated statistical method. RESULTS: Prior to GH treatment, the LH pulse interval did not show a diurnal pattern as found during normal pubertal development. During GH treatment, IGF-1 levels rose significantly. No differences were found in mean LH, LH pulse amplitude and LH pulse interval before and during GH treatment. Oestradiol levels did not change either. CONCLUSIONS: GH substitution in amenorrhoeic GH-deficient women does not alter the pulsatile pattern of LH. This may suggest that GH treatment does not influence central nervous system control of gonadotropin secretion in GHD patients.     

The effect of growth hormone replacement therapy in hypopituitary adults on calcium and bone metabolism*

OBJECTIVE The importance of growth hormone (GH) for normal skeletal growth in childhood and adolescence is well established but much less is known about its action on the adult skeleton. We therefore wished to investigate the effects of replacement treatment with blosynthetic human GH in hypopituitary adults on aspects of calcium homeostatis, bone metabolism and bone mineral mass. PATIENTS Forty hypopituitary adults (21 females and 19 males; aged 19–67 years). DESIGN A prospective randomized double-blind placebo-controlled trial lasting for 6 months. PROTOCOL Following baseline assessments, GH was given in a daily dose of 0·02–0·05 IU/kg body weight subcutaneously (or a placebo (P)) at bedtime. Patients were reviewed at 1, 3 and 6 months. MEASUREMENTS Plasma calcium, phosphate and total plasma alkaline phosphatase were measured at 0, 1, 3 and 6 months. Serum insulin like growth factor I (IGF-I), osteocalcin, procollagen 1 carboxyterminal peptide (P1CP) and intact parathyroid hormone (PTH) level, 24-hour urinary calcium and creatinine excretion were all measured at 0 and 6 months. Bone mineral density of total body and lumbar spine was also measured by dual energy X-ray absorptiometry at 0 and 6 months in 12 patients on GH and 14 on placebo. RESULTS Thirty-eight patients completed the study (18 on GH, 20 on placebo). Serum IGF-I Increased significantly on GH treatment (mean ± SD) (GH: 276 ± 197 vs P: 88 ± 50 μg/l, P < 0 0001 at 6 months). Plasma calcium increased slightly but significantly in the GH-treated group (2·23 ± 0·11–2·29 ± 0·11 mmol/l, P<0·05). At the end of the study, plasma calcium was however similar on GH and placebo (GH, 2·29 ± 0·11; P, 2·26 ± 0·09 mmol/l). Plasma phosphate increased on GH (GH: 1·02±0·23–1·32±0·19; P: 0·99±0·16–0·96±0·12 mmol/l over the 6 months of treatment, P<0·001). There was no significant change in the urinary calcium excretion on GH therapy. Plasma total alkaline phosphatase, osteocalcin and P1CP were significantly higher on GH than P at 6 months (alkaline phosphatase: GH: 104±32 vs P: 69±32 U/I, P<0·01, osteocalcin: GH: 17·2±8·0 vs P: 5·3±3·2 μg/l, P<0·001 and P1CP: GH: 207 ± 152 vs P: 93±31 μg/l, P<0·01). There was no difference in the intact parathyroid hormone level (GH: 31 ± 14 vs P:31 ± 15 ng/l, NS). No significant change was observed in bone mass after 6 months of GH treatment, either in total body bone mineral content or in the lumbar spine. CONCLUSION In this large study, GH replacement in hypopituitary adults for 6 months increased bone turnover but did not affect bone mineral content. Longer-term studies are required to assess further any effect on bone mass.     

Serotoninergic control of gonadotrophin and prolactin secretion in women

OBJECTIVE Due to conflicting observations from previous investigations, the role of serotonin (5-HT) in the regulation of the human menstrual cycle has not been clearly established. We have therefore investigated the possible participation of 5-HR in the control of gonadotrophin and PRL secretion in women, using the potent 5-HT₃ receptor antagonist ondansetron as a pharmacological probe. DESIGN Serum profiles of LH, FSH and PRL were obtained in 9 normally cycling women during a control and a treatment cycle, during which ondansetron (8 mg orally) was administered daily. On day 10 of both cycles, the serum pulsatility of LH, FSH and PRL was assessed by frequent blood sampling (at 10-minute intervals for 10 hours). Pituitary responsiveness was tested by administration of a GnRH bolus (25 μg I.v. after 8 hours). MEASUREMENTS LH, FSH and PRL were serially determined in all blood samples by immunofluorescence assays. The resulting hormone data arrays were searched for significant fluctuations by the Cluster pulse algorithm. RESULTS Compared with control cycles, the temporal organization and the endocrine characteristics of the treatment cycles remained virtually unaltered. Serotonin antagonism did not noticeably affect the LH pulse attributes (frequencies, interpulse intervals, amplitudes). Although FSH amplitudes declined markedly (P < 0·05), the remaining pulse attributes were unchanged. A clear increase (P < 0·05) in the PRL pulse frequency was noted, while PRL pulse amplitudes tended to increase (P= 0·1). Gonadotrophin and PRL release in response to GnRH administration was unaltered by ondansetron treatment. CONCLUSIONS Serotoninergic blockade by a selective 5-HT₃ receptor antagonist failed to modify pulsatile LH secretion, but induced distinct changes in episodic FSH and PRL secretion. Since the pituitary gonadotrophin and PRL responsiveness remained unaltered during 5-HT₃ receptor blockade, the observed alterations in the FSH and PRL secretion presumably relate to altered hypo-thalamic regulation of these pituitary hormones. Thus, the central regulation of pulsatile FSH and PRL release in women appears to involve 5-HT₃ receptor-mediated processes.     

Abnormal twenty-four hour pattern of pulsatile luteinizing hormone secretion and the response to naloxone in women with hyperprolactinaemic amenorrhoea

OBJECTIVE Hyperprolactinaemic amenorrhoea is associated with disturbances of pulsatile gonadotrophin secretion. The underlying mechanism remains unclear and the aim of this study was to investigate the 24-hour secretory pattern of gonadotrophins in women with hyperprolactinaemic amenorrhoea. The effect of opioid blockade using naloxone infusion on LH secretory pattern was also studied. DESIGN The secretory patterns of LH, FSH, PRL and their responses to naloxone infusion were studied by serial blood samples collected at 10-minute intervals for 24 hours. On the following day, naloxone was infused at a dose of 1 6 mg per hour for 4 hours. PATIENTS Eight women with hyperprolactinaemic amenorrhoea, two women hyperprolactinaemic but with normal ovarian cycles, and nine control subjects in the early follicular phase of menstrual cycle. MEASUREMENTS Concentrations of LH, FSH and PRL were measured in plasma samples obtained at 10-minute intervals for 24 hours. In one woman, concentrations of urinary oestrone glucuronide were measured daily during treatment with pulsatile GnRH. RESULTS The number of LH pulses per 24 hours was significantly fewer in women with hyperprolactinaemic amenorrhoea than in those with hyperprolactinaemia with normal cycles or control subjects (mean ± SEM 4.5 ± 2.4 vs 13.5 ± 2.5 vs 17 3±0 8, P<0 001). The magnitude of each episode of secretion was significantly higher in the hyperprolactinaemic amenorrhoeic women (P<005) so the overall mean concentrations of LH throughout the 24-hour period was similar in the three groups (5 2±1 1, 4.8±0 8 and 5.2 ±0.4 U/I respectively). In women with hyperprolactinaemic amenorrhoea there was no significant change in the pattern of LH secretion during sleep in contrast to the control women in whom there was a slowing in the LH pulse frequency during the night. There was no significant change in the mean concentrations of LH, FSH and PRL during the naloxone infusion. There were also no significant changes in the LH pulse frequency in response to naloxone infusion when compared with an equivalent period of time in the previous 24 hours. In one hyperprolactinaemic amenorrhoeic woman, follicular development, ovulation and pregnancy were induced when gonadotrophin releasing hormone (GnRH) was infused in a pulsatile manner at a dose of 5 μg every 90 minutes. CONCLUSIONS The suppression of normal ovarian cycles in women with hyperprolactinaemic amenorrhoea is due to a significant reduction in frequency of LH (GnRH) secretion which is not due to an increase in hypothalamic opioid activity. As normal ovarian cycles can occur or be induced by exogenous GnRH in hyperprolactinaemia, it is unlikely that a high level of prolactin by itself inhibits follicular development and ovulation.     

The level of endothelin-like immunoreactivity in seminal fluid correlates positively with semen volume and negatively with plasma gonadotrophin levels

OBJECTIVE The newly discovered vasoactive peptides, endothelin 1, 2 and 3, and their receptors are widely distributed in various non-vascular tissues. Recent studies have suggested the presence, as well as possible regulatory roles, of endothelins at several levels of the pituitary-gonadal axis. We determined the level of endothelin-like immunoreactivity in the seminal fluid and examined its possible correlation with routine semen parameters or plasma levels of FSH, LH or testosterone. DESIGN Prospective study in a tertiary care centre. PATIENTS Ninety-one men attending infertility clinics for male factor, female factor or both. MEASUREMENTS Endothelin-like immunoreactivity was determined in seminal fluid using two radioimunoassays, ET1–21 that measures endothelin and ET-1,2 that measures both endothelin and big endothelin. In addition, the levels of FSH, LH and testosterone as well as routine semen parameters were determined. RESULTS Sperm density ranged from 0 to 315 times 10⁸ with a mean (±SD) of 28.5 times 10⁸ (±48 times 10⁸) sperm/ml and the percentage of motile sperm ranged from 0 to 85% with a mean of 16% (±20.5%). Mean levels of FSH (n = 33), LH (n = 35) and testosterone (n = 35) were 6.4 ± 4.9 IU/I, 3.5 ± 2.8 IU/I and 21 ± 9.4 nmol/l, respectively. Mean ET1-21 level (n = 91) was 81 ± 16.5 pmol/l, and mean ET-1,2 level (n = 33) was 630.5 ± 143 pmol/l. There were significant correlations between the levels of ET1–21 and ET-1,2 (r = 0.37, P = 0.04), ET1–21 and FSH (r = ?0.5, P = 0.006), ET1–21 and LH (r = ?0.46, P = 0.01), and ET1–21 level and semen volume (r = 0.23, P = 0.03). Mean level of ET1–21 or ET-1,2 was significantly lower in patients treated empirically with clomiphene citrate or gonadotrophins (n = 34) compared to untreated (n = 52) patients (P = 0.04). CONCLUSIONS We conclude that in human seminal fluid (1) endothelin-like immunoreactivity that is specific for active endothelin (ET1–21) represents about 13% of the total immunoreactivity; (2) inactive big endothelin or its N-terminal derivative(s) may account for most of the immunoreactivity; (3) the production/secretion of endothelin may be inhibited by LH and/or FSH; and (4) endothelin level correlates positively with seminal fluid volume.     

RELATION OF hCG-STIMULATED STEROIDOGENESIS TO SERUM FSH, LH AND PROLACTIN IN MAN

Nine adult healthy male volunteers were given a single intramuscular injection of 5000 iu of human chorionic gonadotrophin (hCG). Peripheral blood samples were collected up to 7 days after the injection, the sera were analysed for LH, FSH and prolactin and the results were related to changes in the concentrations of testosterone and oestradiol. Serum LH concentrations tended to decrease for 4 days after the hCG injection (to 65% of the 0 h value) but returned to the starting level during the 7-day observation period. FSH was suppressed throughout the experiment and correlated inversely with serum prolactin (r = -0·74, P < 0·01). The first significant decrease was seen at 48 h and the minimum concentration (28 ± 4%, SEM) at 7 days. Prolactin levels changed only slightly during the first 48 h after the injection but increased thereafter, being significantly elevated at 4 days, and reached a maximum (183 ± 22%) at 6 days after hCG adminstration, coinciding with the late phase of the testosterone response to hCG. Between testosterone and prolactin a positive correlation (r = 0·70. P < 0·01) was found during hCG stimulation. The results suggest that endogenous steroid production of the human testis after hCG administration is sufficient to induce changes in gonadotrophin and prolactin secretion. It is further concluded that the feedback mechanism of FSH is more sensitive to increased testicular steroid output following hCG injection than that of LH. It is hypothesized that pituitary prolactin secretion is stimulated by the elevated serum oestradiol concentration at 24–48 h, and the long term testosterone response, observed 2–6 days after the hCG injection, may be partly due to increased prolactin concentrations.     

PULSATILE SECRETION OF LH, FSH, PROLACTIN, OESTRADIOL AND PROGESTERONE DURING THE HUMAN MENSTRUAL CYCLE

The pulsatile secretion of gonadotrophins and ovarian steroids was studied in normal women at different stages of the menstrual cycle. The concentration of LH, FSH, Prolactin (PRL), oestradiol and progesterone were measured in samples of plasma collected every 15 min for 6 h and the frequency and amplitude of each episodic pulse of hormone estimated. Although significant fluctuations occurred in the concentration of each hormone, LH showed the most easily identifiable pulses the frequency of which increased significantly from the early follicular to the late follicular phase of the cycle (3.4±0.3 v. 4.4±0.2 pulses 6 h P<0.01). During the luteal phase the basal concentration of LH (5.6±0.9 U/l), pulse amplitude (7.4±1.7 U/l) and frequency (1.6±0.2/6 h) were much lower than at any stage of the follicular phase (P<0.001). The concentration of FSH and PRL showed a similar but less marked change to that of LH throughout the menstrual cycle with a significant decline in both basal concentration and pulse frequency in the luteal phase of the cycle. Although only 47% of all LH pulses were associated with a pulse of FSH, 70% of FSH and prolactin pulses occurred within 15 min of an LH pulse. The basal concentration of oestradiol increased significantly from the early follicular to the late follicular phase of the cycle (P<0.001). There was evidence of episodic secretion of oestradiol with the frequency of pulses declining from a maximum of 4.3±0.6/6 h in the mid-follicular phase to 1.8±0.5/6 h in the luteal phase (P<0.02). In the follicular phase 74–80% of LH pulses were followed within 100 min by a significant rise in the concentration of oestradiol. It is suggested that:

• 1 the secretion of LH, FSH, PRL, oestradiol and progesterone is episodic in nature;
• 2 a significant number of secretory episodes of FSH, LH and PRL are coincidental;
• 3 the increased secretion of oestradiol from the pre-ovulatory follicle is associated with a rise in the frequency of episodic pulses of LH.

     

Effects of different oral oestrogen formulations on insulin-like growth factor-I, growth hormone and growth hormone binding protein in post-menopausal women

OBJECTIVE Insulin like growth factor-I (IGF-I) levels in post-menopausal women are reduced by oral administration of the synthetic oestrogen ethinyl oestradiol but increased by transdermal delivery of 17 β-oestradiol. Since these oestrogen types are different, the aim of this study was to clarify whether reduction in IGF-I is a specific effect of ethinyl oestradiol or common to other oral oestrogen formulations. DESIGN Randomized cross-over study comparing one month of treatment with ethinyl oestradiol (20 μ g), conjugated equine oestrogen (1 25 mg Premarin) and oestradiol valerate (2 mg). SUBJECTS Six healthy post-menopausal women, age 60 3 ± 5 6 years. MEASUREMENTS Mean 24 hour GH (from hourly sampling), IGF-I, GH binding protein (GHBP), pituitary (LH, FSH) and hepatic function (SHBG and angiotensinogen) were measured. RESULTS All three oestrogen formulations resulted in a significant reduction in IGF-I levels compared to baseline and significant elevations of GH and GHBP (P & lt; 0 05). The percentage increase in GH during oestrogen treatment was significantly related to the percentage decrease in IGF-I levels (P= 0 04). All three oestrogen formulations resulted in significant suppression of LH and FSH and induction of the hepatic proteins, SHBG and angiotensinogen (P <0 05). GHBP increased in parallel with other hepatic proteins. CONCLUSIONS Reduction in IGF-I levels is an intrinsic effect of oral oestrogen therapy and increased GH levels may occur as a result of reduced feedback inhibition by IGF-I. Since GHBP activity is not changed by transdermal oestrogen, we conclude that the liver is a major source of circulating GHBP and that GHBP is an oestrogen sensitive protein.     

The effects of oxandrolone on the growth hormone and gonadal axes in boys with constitutional delay of growth and puberty

OBJECTIVE We studied the effects of oxandrolone on serum concentrations of LH, FSH, testosterone, GH, SHBG, DHEAS, IGF-I and insulin in boys with constitutional delay of growth and puberty. DESIGN Ten boys with constitutional delay of growth and puberty, mean age 138 years (range 12 4-15-5) were studied. Twenty-four-hour serum concentration profiles of GH, LH and FSH were constructed by drawing blood samples at 20-minute intervals. Three study occasions over a period of 6 months were chosen to assess hormone concentrations before, during and 6 weeks after a 3-month course of oxandrolone (2–5 mg once daily) therapy. RESULTS Growth velocity increased during oxandrolone treatment and stayed higher after therapy (pre 3.9 ± 0.5; on 6.3 ± 0.8; post 6.4 ± 0.9 cm/year (mean±SEM) two way ANOVA, F=5.3, P= 0.02). Oxandrolone had androgenic effects, suppressing mean serum LH concentrations from 1.7 ± 0.3 to 1.1 ± 0.2 U/I and serum testosterone concentrations from 1.9 ± 0.6 to 0.8 ± 0.1 nmol/l. SHBG concentrations were also reduced from 130.9 ± 14.6 to 307±73 nmol/l. Serum GH concentration fell slightly from 5.9 ± 0.6 to 4.8 ± 0.5 mU/l. After cessation of treatment, there was a significant‘rebound’in mean 24-hour serum LH (2.6 U/l ± 0.4) and testosterone concentrations (3.2 ± 0.9 nmol/ l) but no change in serum GH concentrations. SHBG values also rose but not to the same extent as those observed before therapy (82.0 ± 84 nmol/l). There were no statistically significant differences in serum concentrations of FSH, DHEAS, IGF-I and insulin over the study period. In a stepwise multiple regression analysis of factors that might influence the growth rate observed, the 24-hour mean serum testosterone concentration and the treatment (on or off) with oxandrolone were the main influences. The relationship was described by the equation Height velocity = 0.69 (24-hour mean serum testosterone concentration) +1 70 (treatment regimen) + 3.37 (adjusted R²= 0.35, F= 8.39, P= 0.001). CONCLUSIONS Oxandrolone has an androgenic action as shown by changes in serum LH, testosterone and SHBG concentrations and by the lack of effect on FSH. No effect of oxandrolone on the GH axis was documented. We suggest that the growth promoting effects of oxandrolone are related in part to the mild androgenic effects of the steroid and the growth acceleration following oxandrolone withdrawal may reflect increasing total serum testosterone concentrations and decreasing levels of SHBG and progress in puberty.     

GH sensitivity of GH-deficient adults is dependent on gender but not timing of onset

Background Females secrete 2–3‐fold greater amounts of GH compared with males despite maintaining similar IGF‐I levels. IGF‐I generation tests in healthy subjects suggest this discordancy results from relative resistance to GH in females. In GHD females the presumed relative insensitivity to GH is reflected by a lower basal IGF‐I and the need for higher GH maintenance doses during replacement. Adults with severe GHD of childhood‐onset (CO) have lower basal IGF‐I SDS and require higher GH maintenance doses compared with adult‐onset (AO) patients with GHD of equal severity. We hypothesised CO‐GHD adults to be less sensitive to GH than AO‐GHD patients. Methodology In a single site study we analysed the incremental change in IGF‐I (ΔIGF‐I) in 116 GHD adults following initiation of GH replacement. The data were corrected to provide ΔIGF‐I/mg GH because of slight variances in initial GH dose. Results Following GH replacement ΔIGF‐I was 230 ± 245 and 356 ± 278 ng/ml/mg GH in females and males, respectively (P = 0·01). In CO and AO patients ΔIGF‐I was 282 ± 206 and 294 ± 292 ng/ml/mg GH, respectively (P = 0·83). Further analysis after stratification by both gender and timing of onset of GHD showed ΔIGF‐I was 226 ± 164, 324 ± 228, 231 ± 268, and 373 ± 304 ng/ml/mg GH in the CO females, CO males, AO females, and AO males, respectively (AO males vs. AO females, P = 0·03; CO males vs. CO females, P = 0·17; AO males vs. CO males, P > 0·05; AO females vs. CO females, P > 0·05). Multiple linear regression with ΔIGF‐I as the dependent variable and age, gender, BMI, baseline IGF‐I level, and timing of onset as independent variables showed ΔIGF‐I to be dependent on gender alone (R = 0·28, P = 0·004). Age (P = 0·44), BMI (P = 0·54), baseline IGF‐I level (P = 0·63) and timing of onset (P = 0·61) had no effect on ΔIGF‐I. Conclusion We have shown gender to have a significant impact on GH sensitivity in GHD adults, which, at least in part, explains differences in maintenance dosages during replacement. None of the additional variables impacted significantly on GH sensitivity. The lower basal IGF‐I SDS and higher GH replacement requirement reported in CO compared with AO patients cannot be explained by differences in sensitivity to GH.     

Inhibition of growth hormone release after the combined administration of CHRH and GHRP-6 in patients with Cushing's syndrome

OBJECTIVE In patients with Cushing's syndrome there is a blunted OH response to all types of stimuli. Although Inferential data point towards a direct perturbation in the pituitary exerted by glucocorticoids, the bask mechanism is unknown. His-d -TRP-ALA-TRP-d -Phe-Lys-NH₂ (GHRP-6) is a synthetic hexapeptlde which releases GH by a direct pituitary effect through receptors other than GHRH receptors. Furthermore, the combined administration of GHRH and GHRP-6 is able to induce a large OH discharge even in some pathological states such as obesity, associated with GH blockade. To gain further insight into the disrupted mechanisms of GH secretion, Cushing's syndrome patients were challenged with either GHRH, GHRP-6 or GHRH together with GHRP-6. A group of normal subjects was included for control purposes. DESIGN Three different tests were undertaken: (a) GHRH 100 μg I.v.; (b) GHRP-6 100 μg I.v. and (c) GHRH plus GHRP-6 100 μg I.v. of each; administered to each subject on different days, at least 4 days apart. PATIENTS Ten patients (8 women, 2 men) with untreated Cushing's syndrome, 9 Cushing's disease and 1 adrenal adenoma. Five healthy volunteers (3 women, 2 men) of similar ages served as a control group. MEASUREMENTS Plasma OH levels were measured by immunoradiometric assay. RESULTS The areas under the curve (AUC) of OH secretion (mean ± SEM In μ/1/120 mi) in the control subjects after each test were: GHRH, 1420 ± 330; GHRP-6, 2278 ± 290 and GHRH plus GHRP-6,7332 ± 592 (P < 0·05 vs each compound alone). The AUCs for Cushing's syndrome patients were: GHRH, 248 ± 165; GHRP-6 530 ±170 and for GHRH plus GHRP-6, 870 ± 258 (P < 0·05 vs GHRH alone). After the combined stimulus only one out of the ten patients with hypercortisolism showed a GH peak over 20 μ/l, while ail the controls had a peak over 04mU/l. CONCLUSIONS GHRP-6 induced OH secretion as well as the OH discharge elicited by GHRH and GHRP-6 are considerably reduced in Cushing's syndrome patients. This suggests that the main impairment of GH secretion in that pathological state resides at pituitary level.     

Metabolic changes during the defunctionalized stage after ileal pouch-anal anastomosis

Metabolic changes between the preoperative period and the defunctionalized stage after ileal pouch-anal anastomosis were investigated in 21 patients. Aspects studied included weight change, renal function, liver function, lipid metabolism, and two hematologic parameters. Of 21 patients, 19 lost weight. Cholesterol levels decreased from 183±30 IU/I to 122±48 IU/I (P<.0001). Triglyceride levels rose from 95±29 IU/I to 190±86 IU/I (P<.01). Significant elevations were seen in values of four liver function tests: SGOT, SGPT, lactic dehydrogenase, and alkaline phosphatase (P<.05). Blood urea nitrogen levels increased from 11.1±4.7 mg/100 ml to 21.8±24.8 mg/100 ml (P<.05). Serum creatinine levels rose from 0.97±.18 mg/100 ml to 1.5±1.2 mg/100 ml (P<.05). Uric acid levels increased from 5.6±1.8 mg/100 ml to 7.5±2.3 mg/100 ml (P<.001). Hemoglobin values did not change significantly. Platelet counts rose from 304,000±79,000 to 447,800±189,000 (P<.05). Identification of these systematic alterations in metabolic parameters during the defunctionalized stage can aid the physician in management of these patients. Read at the meeting of the American Society of Colon and Rectal Surgeons, San Diego, California, May 5 to 10, 1985.     

Metabolic effects of growth hormone administered subcutaneously once or twice daily to growth hormone deficient adults

OBJECTIVE The aim of this study was to compare the metabolic effects of GH administered subcutaneously either once or twice daily. The actions of GH might depend upon a pulsatlle pattern of serum GH. Pulsatile and continuous intravenous delivery of GH, however, induce similar short-term metabolic effects in GH deficient patients. An improved growth response is obtained in GH deficient children when a fixed weekly GH dose Is administered by dally subcutaneous injections instead of twice or thrice-weekly intramuscular injections. A more pulsatile pattern and serum GH levels above zero might be achieved by further increasing the Injection frequency. Increased daytime GH levels might, however, adversely affect the circadian patterns of metabolic indices, whlch have been demonstrated to be more successfully reproduced by evening compared with morning GH administration. DESIGN AND MEASUREMENTS In a cross-over study, 8 GH deficient patients (age 16–43 years) were treated with 3IU/m²/24h of human GH. The dose was injected in the evening for 4 weeks and for another 4 weeks two-thirds was injected in the evening and one-third in the morning. At the end of each period the patients were admitted to the hospital for 37 hours. Steady-state profiles of GH, IGF-I, IGF binding proteins 1 and 3, Insulin, glucose, lipid Intermediates and metabolites were obtained following administration of 3IU/m² of GH (at 1900 h (one injection) and at 1900 and 0800 h (two injections). RESULTS Similar mean integrated levels of serum GH (mUII) were obtained (7·46 ± 0·84 (one injection) vs 6·46 ±0·62 (two Injections) (P = 0·15). Mean levels ± SEM of serum IGF-I (μg/I) were significantly increased (P < 0·01) following two daily GH Injections (330·3±48·1 (one Injection) vs 399·1±53·0 (two injections). Serum IGFBP-3 levels were not signlflcantly different on the two occasions, while levels of the GH Independent IGFBP-1 (μg/l) were slightly but significantly lower following twice-dally GH injections (1·61±0·42 vs 1·13 ±0·56, respectively (P < 0·04). The pattern of IGFBP-1 was opposite to that of insulin. Similar levels of insulin and glucose were obtained with both GH regimens, while levels of non-esterlfied fatty acids were significantly higher following once-dally GH injection (P < 0·001). CONCLUSIONS Twice-dally GH injections, apart from producing a more physiological serum GH profile, were superior to one Injection in increasing serum IGF-I and decreasing IGFBP-1 levels. Both of these changes tend to amplify the effects of the administered GH. Twice-daily Injections, however, resulted Ln lower night-time levels of lipid Intermediates.     

THYROID HORMONE, OESTROGEN, AND GLUCOCORTICOID EFFECTS ON TWO DIFFERENT PITUITARY GLYCOPROTEIN HORMONE ALPHA SUBUNIT POOLS

Seven hypothyroid women (six postmenopausal and one premenopausal) were treated with 200 or 300 μg of levo-T4 daily in order to suppress the secretion of TSH and its alpha and beta subunits. After such therapy, serum TSH and beta subunit of TSH (TSH-β) levels were usually not detectable. Serum alpha decreased from a mean value of 4.5 ± 0.8 ng/ml to 2.8 ± 0.4 ng/ml (P > 0.01). Serum LH and FSH levels were unchanged. Oestrogen administration (20 mg diethylstilboestrol daily for 3 or 5 days) to these patients further decreased mean serum alpha to 1.9 ± 0.2 ng/ml (P > 0.005). In addition serum LH, FSH, and the beta subunits of LH and FSH decreased with oestrogen treatment. In separate experiments glucocorticoids (dexamethasone 4 mg every 6 hours for 10 doses) were administered to eight normal individuals, four women with decreased thyroid reserve, and one hyper-thyroid woman. Not only did basal and TRH-stimulated TSH secretion decrease, but secretion of alpha and TSH-β also decreased after dexamethasone administration, with the largest fall in the patients with decreased thyroid reserve. The change in these thirteen patients’ alpha subunit increment after TRH administration was from a mean of 1.6 to 1.0 ng/ml with glucocorticoids; the change in TSH-β was from a mean of 1.1 to 0.7 ng/ml. Serum LH and FSH concentrations were not altered by glucocorticoid administration. These studies have demonstrated two different pools of alpha subunits in the pituitary gland. Thyroid hormone and glucocorticoids decreased secretion of alpha subunits arising from the thyrotroph; oestrogen decreased secretion of alpha subunits arising from the gonadotroph.