The control of steroidogenesis by human fetal adrenal cells in tissue culture. IV. The effect of exposure to placental steroids

The effect upon steroidogenesis of adding various steroids produced by the placenta was studied in short term cultures of human fetal adrenal cells. The addition of high concentrations (10(3) ng/ml) of estrone or estriol inhibited the production of cortisol, but only the former elicited a parallel increase in dehydroepiandrosterone (DHA) production. Estradiol was effective in inhibiting delta-4-3-ketosteroid production at concentrations of 10-100 ng/ml, levels which approach those found in the fetal circulation, while DHA production was increased at concentrations of 1 microgram/ml. The addition of progesterone (4 microgram/ml) to the medium caused increased production of cortisol and corticosterone, but had no effect on DHA production. Pregnenolone (4 microgram/ml) increased the basal production of DHA and slightly impaired both basal and ACTH-stimulated aldosterone production, but had no effect on cortisol production. The data demonstrate that the many fetal and placental factors which have been studied to date, only ACTH and estrogens can interact to produce the characteristic fetal pattern of steroidogenesis. Preliminary studies indicate that this effect-stimulated aldosterone production, but had no effect on cortisol production. The data demonstrate that the many fetal and placental factors which have been studied to date, only ACTH and estrogens can interact to produce the characteristic fetal pattern of steroidogenesis. Preliminary studies indicate that this effect-stimulated aldosterone production, but had no effect on cortisol production. The data demonstrate that the many fetal and placental factors which have been studied to date, only ACTH and estrogens can interact to produce the characteristic fetal pattern of steroidogenesis. Preliminary studies indicate that this effect of estrogen is not influenced by other peptide hormones such as hCG, human prl, beta-lipotropin, corticotropin-like intermediate lobe peptide, or beta-endorphin. A revised model of the fetoplacental steroidogenic unit is presented which may explain both normal and fetal hyperplasia and postnatal involution of the adrenal cortex and the variations from this pattern seen in apituitary children.     

HCG binding and stimulation of testosterone biosynthesis in the human fetal testis.

The role of hCG in the regulation of testicular steroid production in human fetuses from 14 to 20 weeks gestational age was studied. Saturable binding of 125I-hCG to testicular homogenates was demonstrated, and physiologic concentrations of hCG were able to stimulate testosterone formation in testicular minces without the addition of exogenous precursors. In five fetses of 16-20 weeks gestational age, the capacity to bind hCG varied from 25.6 to 42.2 pg/mg wet tissue. The association constant of binding was 1.07+/-0.12 X 10(10) M-1. Testicular minces from six other fetuses (gestational age 14-19 weeks) were incubated in the presence of concentrations of 0, 0.5, 5 or 50 ng/ml NIH-hCG (1 mg=10,000 IU), which are within the physiologic range. Preincubation of 30 min in excess buffer was necessary to observe clear differences in testosterone production rates between controls and hCG stimulated testicular tissues. The greatest increase in testosterone production occurred when the hCG concentration was increased from 0.5 to 5 ng/ml. Little additional stimulation was observed at a concentration of 50 ng/ml. Maximal production rates of up to 12 ng/mg tissue/h were seen. It is concluded that human fetal testes bind hCG, and that physiologic levels of hCG stimulate fetal testicular testosterone formation in vitro at this stage of gestation.     

Human chorionic gonadotropin stimulation of estradiol production and androgen antagonism of gonadotropin-stimulated responses in cultured human granulosa-luteal cells

Baseline and gonadotropin-stimulated estradiol production were examined in long term cultures of human granulosa-luteal cells isolated from women undergoing in vitro fertilization. Estradiol production declined by 70% during the first 48 h in culture and was minimally stimulated by the addition of hCG to the culture medium. During subsequent culture from 48-120 h estradiol production was significantly increased over control levels by hCG concentrations greater than 0.1 IU/ml. Incubation with testosterone stimulated estradiol production 100-fold in the presence and absence of gonadotropin. hCG (0.01-10 IU/ml) stimulated a 3- to 13-fold increase in progesterone production. However, at hCG concentrations greater than 1 IU/ml, coincubation with testosterone (10(-7) M) significantly inhibited progesterone production. Dihydrotestosterone also inhibited progesterone production, but to a lesser extent than testosterone. Freshly isolated granulosa-luteal cells specifically bound small amounts of [125I]hCG (less than 1,000 cpm/10(5) cells). Glycine buffer wash was shown to reversibly remove more than 88% of bound hCG and, in freshly isolated cells, increased [125I]hCG binding by 100%. In 5-day cultures, specific [125I] hCG binding nearly doubled from 52,000 cpm/10(5) cells in control cultures to 87,000 cpm/10(5) cells in cultures treated with hCG (0-5 IU/ml). At the highest concentration of hCG (5 IU/ml), testosterone (10(-7) M) significantly inhibited the amount of [125I]hCG specifically bound. In summary, estradiol production in long term cultures of granulosa-luteal cells appears to be gonadotropin dependent. In addition, the presence of testosterone (10(-7) M) antagonizes hCG-stimulated progesterone and LH receptor production by these cells.     

Human chorionic gonadotropin and prolactin modulation of early luteal function and luteinizing hormone receptor-binding activity in cultured human granulosa-luteal cells

These studies were undertaken to explore the roles of both hCG and PRL in the modulation of early luteal function in the human. Human granulosa-luteal cells isolated during cycles stimulated by human menopausal gonadotropin hCG were obtained at the time of follicle aspiration and cultured to determine the effects of hCG and PRL on both progesterone and hCG receptor binding. Progesterone production by hCG-stimulated granulosa-luteal cells was increased 3.5-fold over unstimulated levels after 120 h, with maximal stimulation at hCG concentrations greater than 1 IU/ml. [125I]hCG binding to granulosa luteal cells was increased 3-fold in cells cultured with hCG (10 IU/ml) after both 48 h (P less than 0.03) and 96 h (P less than 0.02) in culture. hCG (1 IU/ml) stimulated a significant increase in progesterone production above basal levels after 72 h of culture, which continued to increase until 96 h of culture; 20 alpha-dihydroprogesterone (20 alpha-OH progesterone) production also was increased by hCG (1 IU/ml) at 72 h of culture, but unlike progesterone production, showed no further increase. In both the presence and absence of hCG, granulosa-luteal cells cultured with PRL (100 ng/ml) produced significantly more 20 alpha-OH progesterone (P less than 0.04 and P less than 0.02, respectively) after several days than cells cultured without PRL. In addition, progesterone production in the presence of hCG (10 IU/ml) decreased significantly (P less than 0.04) as 20 alpha-OH progesterone levels increased. Equivalent amounts of [125I]hCG were bound by human granulosa-luteal cells cultured with and without PRL (100 ng/ml). These results show that cultured human granulosa-luteal cells are responsive to hCG, with parallel increases in both progesterone production and [125I]hCG receptor binding. The presence of PRL (100 ng/ml) had no effect on [125I]hCG binding. In both the presence and absence of hCG, PRL resulted in an increase in 20 alpha-OH progesterone production and, in the presence of hCG (10 IU/ml), a decrease in progesterone production after several days in culture.     

Increases in circulating insulin-like growth factor I levels by the oral growth hormone secretagogue MK-0677 in the beagle are dependent upon pituitary mediation

It has been well established that the spiroindoline sulfonamide MK-0677 stimulates GH secretion from the pituitary both in vitro and in vivo. MK-0677 has also been shown to increase serum insulin-like growth factor I (IGF-I) and cortisol levels in vivo; these increases are assumed to be driven by the increased serum GH and ACTH levels, respectively. However, such increases could also be due to a direct stimulatory action of MK-0677 at the level of the liver and adrenal cortex. To address this possibility, we investigated whether MK-0677 increased IGF-I and cortisol levels in hypophysectomized dogs. Baseline GH, IGF-I, and cortisol responses to MK-0677 (1 mg/kg, orally) were initially determined. Hypophysectomy (hypox; n = 7) or sham surgery (sham; n = 5) was then carried out. Six days postsurgery, the GH and cortisol responses to MK-0677 were reevaluated in each dog. In addition, each dog was treated with porcine GH (PST; 0.1 IU/kg, s.c.) to confirm the responsiveness of the GH-IGF-I axis. The mean peak GH increases in response to MK-0677 in the presham dogs (83.7 +/- 19.2 ng/ml), post-sham dogs (108 +/- 26.2 ng/ml), and pre-hypox dogs (121.2 +/- 13.6 ng/ml) were not significantly different. Mean peak GH levels were unchanged after MK-0677 administration in the hypox dogs (2.3 +/- 0.7 ng/ml). Before surgery, serum IGF-I levels increased to 243 +/- 27 and 224 +/- 47 ng/ml in the sham and hypox groups, respectively, after MK-0677 administration. Surgery was associated with a marked (> or =50%) decrease in serum IGF-I levels. MK-0677 administration increased IGF-I levels in the sham dogs from 78 +/- 14 to 187 +/- 31 ng/ml, whereas IGF-I levels remained unchanged (17.7 +/- 2.4 ng/ml) in the-hypox dogs. PST treatment increased IGF-I levels in the sham dogs from 162 +/- 30 to 325 +/- 32 ng/ml. In the hypox dogs PST treatment restored IGF-I to physiological levels (from 17.7 +/- 2.4 to 199 +/- 41 ng/ml). Cortisol was increased after MK-0677 administration 3.7-fold in the pre-sham, 3.6-fold in the post-sham, and 3.6-fold in the pre-hypox dogs, but no increase was seen in the post-hypox dogs. ACTH GEL administration (2.2 U/kg, i.m.) to hypox dogs returned cortisol to normal physiological levels, demonstrating the functional integrity of the adrenal cortex. This study demonstrates that the GH secretagogue MK-0677 does not directly stimulate an increase in serum IGF-I or cortisol levels, but depends upon the presence of an intact pituitary.     

Chronic human chorionic gonadotropin administration in normal men: evidence that follicle-stimulating hormone is necessary for the maintenance of quantitatively normal spermatogenesis in man

The role of FSH in the maintenance of spermatogenesis in man is poorly understood. To determine whether normal serum levels of FSH are necessary for the maintenance of quantitatively normal spermatogenesis, we first studied the effect on sperm production of selective FSH deficiency induced by chronic administration of hCG in normal men. Then, we determined the effect of FSH replacement in some of these men. After a 3-month control period, eight normal men (aged 30-39 yr) received 5000 IU hCG, im, twice weekly for 7 months. Then while continuing the same dosage of hCG, subjects simultaneously received 200 mg testosterone enanthate (T), im, weekly for an additional 6 months. hCG administration alone resulted in partial suppression of the mean sperm concentration from 88 +/- 24 (+/-SEM) million/ml during the control period to 22 +/- 7 million/ml during the last 4 months of hCG treatment (P less than 0.001 compared to control values). With the addition of T to hCG, sperm counts remained suppressed to the same degree. Except for one man who became azoospermic while receiving hCG plus T, sperm motilities and morphologies remained normal in all subjects throughout the entire study. During both the hCG alone and hCG plus T periods, serum FSH levels were undetectable (less than 25 ng/ml), and urinary FSH levels were comparable to those in prepubertal children and hypogonadotropic hypogonadal adults. We replaced FSH activity in four of the eight men in whom prolonged selective FSH deficiency and partial suppression of sperm production were induced by hCG administration. Immediately after the period of hCG plus T administration, T was stopped in four men who continued to receive hCG alone (5000 IU, im, twice weekly) for 3 months. Then, while continuing the same dosage of hCG, these men received 100 IU human FSH, sc, daily (n = 2) or 75 IU human menopausal gonadotropin, sc, daily (n = 2) for 5-8 months. During the second period of hCG administration alone, serum FSH levels were undetectable (less than 25 ng/ml), and sperm concentrations were suppressed (34 +/- 13 million/ml) compared to the control values for these four men (125 +/- 39 million/ml; P less than 0.001). With the addition of FSH to hCG, FSH levels increased (213 +/- 72 ng/ml) and sperm concentrations rose significantly, reaching a mean of 103 +/- 30 million/ml (P less than 0.03 compared to hCG alone).(ABSTRACT TRUNCATED AT 400 WORDS)     

The effects of adrenocorticotropin and prolactin on adrenal dehydroepiandrosterone secretion in the baboon fetus

The present study was designed to determine whether PRL, in addition to ACTH, stimulates adrenal secretion of dehydroepiandrosterone (DHA) in vivo at midgestation in the baboon fetus (Papio anubis). On day 100 of gestation (term = day 184), fetuses were exteriorized, and a constant infusion of saline (0.1 ml/min) was initiated via a fetal femoral vein. Forty minutes later, a bolus injection of 30 nmol ACTH/ml saline (n = 5), 40 nmol ovine PRL/ml saline (n = 4), or 1 ml saline (n = 5) was administered via the fetal femoral venous catheter. ACTH (0.15 nmol/min.0.1 ml saline), PRL (0.20 nmol/min.0.1 ml saline), or saline (0.1 ml/min) was then infused for an additional 25 min. Blood samples were obtained from the contralateral fetal femoral vein and the maternal saphenous vein immediately before and after peptide infusion and from the umbilical vein and artery at the end of the infusion. Fetal serum DHA concentrations (range, 9-11 micrograms/100 ml) were significantly increased (P less than 0.05) by PRL and ACTH, but not by saline. In contrast, fetal concentrations of cortisol (15-20 micrograms/100 ml) and DHA sulfate (DHAS; 13-18 micrograms/100 ml) were not altered by infusion of test substances into the fetus. The maternal concentrations of F (49-61 micrograms/100 ml) and DHAS (19-22 micrograms/100 ml) exceeded (P less than 0.05) respective values in the fetus, whereas DHA concentrations (2-3 micrograms/100 ml) in the mother were lower (P less than 0.05) than those in fetal serum. The serum concentrations of DHA, DHAS, and cortisol in the mother were not altered by PRL or ACTH. Regardless of the treatment, concentrations of DHA and DHAS in umbilical vein were lower (P less than 0.05) than those in the umbilical artery. These findings indicate that PRL as well as ACTH are effective in vivo in stimulating serum DHA concentrations in fetal baboons at midgestation. The greater concentration of DHA in umbilical artery vs. umbilical vein as well as the lack of response in maternal DHA concentrations indicate that the site of action of PRL and ACTH is the fetal adrenal. Therefore, we conclude that at midgestation, there is the potential for multifactorial regulation of baboon fetal adrenal androgen production and that PRL, in addition to ACTH, can function as a fetal adrenocorticotropic factor in vivo.     

Role of hCG in regulation of the fetal zone of the human fetal adrenal gland.

It has been suggested that hCG is a trophic hormone for the fetal zone of the human fetal adrenal gland. To test this hypothesis, the isolated fetal zones of adrenals from eight fetuses (12-17-week gestation age) were superfused in the presence or absence of hCG. Dehydroepiandrosterone sulfate (DHAS) was measured in the superfusion effluent. A significant increase in DHAS production was observed in the presence of hCG. DHAS secretion decreased during the first 60 min in the control and experimental superfusions from 83 +/- 10.0 (mean +/- SE) to 71 +/- 8.0, and from 90 +/- 9.0 to 70 +/- 6.0 ng/100 mg/ml, respectively. In the presence of hCG (250 ng/ml), DHAS secretion increased significantly (P less than 0.01) over the controls to 116 +/- 12.0 at 120 min, and remained above the controls thereafter. These results support the hypothesis that hCG is one of the regulators of DHAS production by the human fetal adrenal gland early in gestation. As we found that ACTh stimulated DHAS secretion in a previous study and as there is indirect evidence for a role of ACTH in DHAS regulation late in pregnancy, these observations suggest dual regulation by hCG and ACTH early in pregnancy, and a possible transition to ACTH regulation of the fetal zone of the human fetal adrenal after midgestation.     

Prolactin stimulates adrenal androgen secretion in infant baboons

It has been suggested that pituitary factors other than ACTH modulate adrenal steroidogenesis during maturation of the pituitary-adrenocortical axis. Therefore, we determined whether hormones other than ACTH influence the production of cortisol (F), dehydroepiandrosterone (DHA), and DHA-sulfate (DHAS) in baboon infants studied between 8 and 24 months of age. Animals (three males, two females) were sedated with ketamine and peripheral blood samples taken 20, 10, and 0 min before a 90-min constant iv infusion of 448 pmol/min of either ACTH, ovine PRL, ovine GH, 2.4 nmol/min human CG (hCG), or normal saline. Serum F, DHA, and DHAS concentrations of blood samples obtained during the infusion (70, 80, 90 min) were averaged and compared with average pretreatment values. Each animal received each of the treatment protocols which included a minimum recovery period of 3-6 weeks. The serum concentrations of F, DHA, and DHAS did not vary with age and averaged (mean +/- SE) 24 +/- 2, 1.9 +/- 0.2, and 36 +/- 5 micrograms/dl, respectively. Compared to pretreatment values, ACTH increased (P less than 0.05) mean serum F concentrations by 155 +/- 20%; PRL, GH, hCG, and saline had no effect. In contrast, serum DHA concentrations were stimulated (P less than 0.05) by both ACTH (131 +/- 20%) and PRL (58 +/- 18%); GH, hCG, and saline had no effect. Similar findings were observed for serum DHAS concentrations. These findings indicate that the majority of serum androgens in young baboons is of adrenal origin. Therefore, we conclude that PRL, in addition to ACTH, may also be an adrenocorticotrophic factor in baboon infants. However, in contrast to ACTH, the action of PRL on the adrenal is apparently specific for androgen production.     

Interaction of phorbol ester and adrenocorticotropin in the regulation of steroidogenic P450 genes in human fetal and adult adrenal cell cultures.

The role of protein kinase-C-dependent mechanisms in steroidogenic enzyme gene expression was studied in primary cultures of human fetal and adult adrenals. Cells were first cultured for 7-10 days and then stimulated with ACTH or 12-O-tetradecanoyl phorbol-13-acetate (TPA), a protein kinase-C activator, for 1-2 days. Cytoplasmic RNA was extracted and analyzed by Northern and dot blotting with 32P-labeled cDNA probes for P450scc (cholesterol side-chain cleavage enzyme/20,22-desmolase), P450c17 (17 alpha-hydroxylase/17,20-lyase), and P450c21 (21-hydroxylase); for P450c11 (11 beta-hydroxylase/18-hydroxylase/18-methyl oxidase), a 30-mer oligonucleotide was used as a probe. ACTH (200 ng/ml) increased the accumulation of all of the studied steroidogenic enzyme mRNAs in both fetal and adult cultures by several-fold. TPA inhibited this accumulation in a dose-dependent manner (0.01-100 ng/ml), whereas the inactive phorbol ester 4 alpha-phorbol-12,13-didecanoate was without effect. On the other hand, in the absence of ACTH, TPA slightly increased all steroidogenic P450 mRNAs in adult cultures. In fetal cultures TPA slightly increased P450scc, P450c11, and P450c21 mRNA levels, whereas it decreased P450c17 mRNA. (Bu)2cAMP and cholera toxin increased steroidogenic enzyme mRNAs such as ACTH. TPA down-regulated (Bu)2cAMP- and cholera toxin-induced P450mRNAs in the same way as ACTH-induced mRNAs. The secretion of ACTH-stimulated cortisol, dehydroepiandrosterone sulfate, and aldosterone was decreased by TPA in both fetal and adult cultures. The basal steroid production was slightly increased by TPA in both culture types. The changes in steroid production correlated well with the alterations in the steroidogenic enzyme gene expression. Our results show that the inhibitory effect of TPA on ACTH-stimulated adrenal steroidogenesis is mediated at the mRNA level of steroidogenic enzymes. Thus, it seems likely that both protein kinase-C- and cAMP-dependent mechanisms are involved in the long term maintenance of steroidogenic enzymes and hormone production in adrenocortical cells.     

Androgen production in primary culture of immature porcine Leydig cells

The present paper examines the steroidogenic responsiveness of immature porcine Leydig cells in primary culture. Both testosterone (T) and dehydroepiandrosterone sulfate (DHAS) secretion were measured under basal conditions and after stimulation with human chorionic gonadotropin (hCG) (25 ng/ml). In medium supplemented with insulin, transferrin, epidermal growth factor (3H) and 0.1% calf serum, cells survived 3-5 days in culture. The production of steroids (under hCG stimulation) is poor on day 0-1 of the culture. On day 2-4 basal T and DHAS levels are 1.9 and 17.0 ng/10(6) cells/24 h. The addition of hCG stimulated T and DHAS production 19- and 6-fold respectively and the average productions were 37 and 109 ng/10(6) cells/24 h. Increasing the serum to 0.5% did not change the viability of the cultures, but increased hCG stimulated T and DHAS production (183 and 188 ng/10(6) cells/24 h). The addition of alpha-tocopherol (vitamin E) to 0.1% calf serum led to a 4-fold increase in stimulated T production (142 ng/10(6) cells/24 h) and maintained full cell viability for more than 5 days. Measurement of 3 beta-ol steroid dehydrogenase activity indicates that the amount of enzyme is 4 times higher at day 2 than at day 0 and 1 (with or without hCG), suggesting a spontaneous maturation of the cells in culture. This might explain the increased T production with time in culture. In cumulative experiments (24 h) the cells do not seem to be desensitized to hCG stimulation following prolonged exposure to 25 ng hCG since the daily steroid production is increasing with time in culture. However, kinetic studies show that steroidogenesis is not linear over a 24 h period. In cumulative experiments the steroid production stops between 12 and 16 h following hCG exposure (5 and 100 ng/ml) and resumes following a medium change. These results suggest that some inhibitory compounds are accumulated in the medium and are controlling the Leydig cell function. Moreover high doses of hCG (100 ng/ml) result in a lower production of steroids and an earlier plateau in the case of DHAS. These results demonstrate that porcine Leydig cells can live and differentiate in hormone- and vitamin-supplemented medium and that auto-feedback mechanisms inhibiting steroid accumulation take place under in vitro conditions.     

Effect of estrogen on pituitary peptide-induced dehydroepiandrosterone secretion in the baboon fetus at midgestation

We have previously shown that ACTH and PRL stimulate baboon fetal adrenal dehydroepiandrosterone (DHA) production both in vitro and in vivo and that estrogen diminishes the responsivity of the adrenal to tropic peptides in vitro. In the present study we determined the effects of increasing placental estrogen production by the administration of androstenedione at midgestation on DHA production by the baboon fetus in vivo. Pregnant baboons were untreated (n = 8) or treated (n = 9) with increasing numbers of androstenedione implants inserted in the mother at 8-day intervals between days 70-100 of gestation (term = day 184). On day 100, the fetuses were exteriorized, and a constant infusion of saline (0.1 ml/min) was initiated via a catheter inserted into a femoral vein of the fetus. At 40 min, a bolus injection of either 30 nmol ACTH or 40 nmol ovine PRL was administered to fetuses. ACTH or PRL (0.2 nmol/min.0.1 ml saline) were then infused for an additional 25 min. The concentrations of serum estradiol (E2) in the uterine vein (20.2 +/- 1.5 ng/ml; mean +/- SE) and estrone (E1) in umbilical vein (11.9 +/- 3.1 ng/ml) of androstenedione-treated baboons were 2-fold greater (P less than 0.05) than respective values in untreated baboons. Baseline concentrations of DHA in the femoral vein of the fetus were similar in all treatment groups (overall mean, 120 +/- 20 ng/ml) and greater (P less than 0.05) than values (27 +/- 3) in the mother. In untreated control baboons, basal DHA concentrations in the fetus were increased (P less than 0.05) by 69 +/- 17% and 94 +/- 29% after fetal injection of ACTH (n = 4) or PRL (n = 4), respectively. In contrast, neither PRL (n = 5) nor ACTH (n = 4) had any effect on serum DHA when injected into androstenedione-treated baboons. Regardless of treatment, injection of ACTH or PRL into the fetus had no effect on DHA concentrations in the mother. Collectively, these findings indicate that the ability of the fetal adrenal to increase DHA production in response to an acute infusion of ACTH or PRL was abolished in baboons in which placental estrogen production was increased prematurely at midgestation. Therefore, we suggest that during the second half of gestation in the baboon a regulatory system may exist in utero, in which there is feedback control of the placental product estrogen on the formation of the fetal adrenal precursor DHA.     

Reduced LH sensitivity in vivo and in vitro of corpora lutea induced during anoestrus by GnRH, and during the late breeding season, in Scottish Blackface ewes

Scottish Blackface ewes were synchronised in mid-breeding (November; group 1; n=12 ewes) or late-breeding season (March; group 2; n=16). Anoestrous ewes (May) were treated with progestagen sponges for 7 days and then given 250 ng GnRH 3-hourly for 24 h, 2-hourly for 24 h and hourly for a further 24 h (group 3; n=12). A second group of anoestrous ewes (group 4, n=19) received three bolus injections (30 microg) of GnRH at 90-min intervals without progestagen pretreatment. After ovulation, ewes were bled twice daily until slaughter (day 4 or day 12: oestrus=day 0). Mid-breeding season (group 1) and anoestrous ewes in group 3 formed 'adequate' corpora lutea (CL) with high plasma progesterone levels (3-4 ng/ml) maintained for at least 12 days, and responded in vivo to ovine LH (oLH) (10 microg) with a rise in plasma progesterone on day 11 (group 3, but not group 1, ewes also responded on day 3). CL minces from these ewes responded to human chorionic gonadotrophin (hCG) in vitro with a dose-dependent increase in progesterone secretion. Ewes in group 4 had a foreshortened luteal phase (8-10 days) and low plasma progesterone levels (approximately 1 ng/ml), consistent with formation of inadequate CL. LH injection failed to induce a significant plasma progesterone increase. Furthermore, although progesterone secretion in vitro in response to maximally stimulating doses of hCG or dibutyryl cAMP (dbcAMP) was similar to that in adequate CL, the sensitivity of these CL to hCG (EC (effective concentration)50, 1 IU hCG/ml) was reduced 10-fold compared with adequate CL (EC50, 0.1 IU hCG/ml; P<0.01). Ewes that ovulated in the late breeding season (group 2) had high plasma progesterone, although levels began to decrease after day 10. Injection of oLH in vivo increased plasma progesterone. However, sensitivity to hCG in vitro (EC50, 0.5 IU hCG/ml) was intermediate between that of adequate luteal tissue (groups 1 and 3; EC50, 0.1 IU/ml) and that of group 4 ewes (EC50, 1 IU hCG/ml). Our data demonstrate a markedly reduced luteal sensitivity to LH in vivo and hCG in vitro in Scottish Blackface ewes with inadequate CL, and suggest that a similar loss of sensitivity to LH may occur in the late breeding season.     

Regulation of baboon fetal adrenal androgen formation by pituitary peptides at mid- and late gestation

A short term incubation of baboon fetal adrenal cells obtained at midgestation and near term was used to determine whether a change in the regulation of androgen formation occurs with advancing gestation. Adrenal glands were removed from baboon (Papio anubis) fetuses on day 100 (mid; n = 7) or day 170 (late; n = 5) of gestation, and cells were dispersed with 0.2% collagenase. Cells (10(5] were incubated at 37 C for 3 h in medium 199 in the presence or absence of 10 nM ACTH, 10 nM ovine PRL, 10 nM ovine GH, 50 nM hCG, or 50 nM human chorionic somatomammotropin. Dehydroepiandrosterone (DHA), DHA sulfate (DHAS), cortisol (F), and androstenedione concentrations were determined in the medium by RIA. At midgestation, ACTH, PRL, and GH elevated (P less than 0.05) DHA (168%, 169%, and 178%, respectively) and DHAS (142%, 210%, and 197%, respectively) formation. Near term, ACTH and PRL retained their ability to stimulate (P less than 0.05) DHA (307% and 220%, respectively), but not DHAS, synthesis. The fetal adrenal at late gestation, however, lost its ability to respond to treatment with GH. hCG and human chorionic somatomammotropin did not stimulate steroidogenesis at either time of gestation. F formation at midgestation was less (P less than 0.05) than that at term and not responsive to ACTH. ACTH stimulated (P less than 0.05) F secretion by 68% in fetal adrenal cells obtained near term. The secretion of androstenedione was not affected by any peptide treatment at either stage of gestation. These data indicate that the responsivity of the baboon fetal adrenal to various pituitary peptides is different at two developmentally distinct stages of gestation. We conclude, therefore, that the regulation of fetal adrenal steroidogenesis changes with advancing gestation.     

Effects of 12-month GH treatment on bone metabolism and bone mineral density in adults with adult-onset GH deficiency

Serum bone-Gla protein (BGP), bone alkaline phosphatase (B-AP), and C-terminal cross-linked telopeptide of type I collagen (ICTP) levels were evaluated in 18 adults with acquired GH deficiency (GHD, 14 males and 4 females, age range: 25-59 yr) before, at 3, 6, 9 and 12 months of rec-GH treatment (0.125 IU/kg/week for the first month, followed by 0.25 IU/kg/week for 11 months) and 6 months after the withdrawal of therapy. Total body bone mineral density (BMD, g/cm2) was measured with dual energy X-ray absorptiometry (Hologic QDR 1000/W) before, at 12 months of GH treatment and 6 months after its withdrawal. Before treatment, BGP (mean+/-SE: 5.1+/-0.4 ng/ml), B-AP (59.4+/-6.5 IU/l), ICTP (3.1+/-0.3 ng/ml) levels of patients were similar to in healthy controls (BGP: 5.4+/-0.1 ng/ml; B-AP: 58.2+/-2.0 IU/l; ICTP: 4.1+/-0.3 ng/ml). GH treatment caused a significant increase of BGP, B-AP, ICTP levels, the maximal stimulation of bone resorption, occurring after 3 months of GH treatment, while the maximal effect on bone formation being evident later (at 6th month). A slight decline in BGP, B-AP, T-AP and ICTP levels occurred at 9-12 months of therapy, although the values remained significantly higher than in basal conditions and with respect to healthy controls. Before treatment, mean total body BMD of patients (1.110+/-0.027 g/cm2, range: 0.944-1.350 g/cm2) was not significantly different (z-score: +0.47+/-0.31, NS) from that observed in healthy controls (1.065+/-0.008 g/cm2, range: 1.008-1.121 g/cm2). GH therapy was associated with a significant reduction of mean total body BMD values (6th month: -1.8+/-0.5%, p<0.01; 12th month: -2.1+/-1.0%, p<0.05 vs baseline), particularly evident in the first six months of treatment. Six months after the withdrawal of GH therapy, BGP (5.9+/-0.5 ng/ml), B-AP (57.3+/-7.0 IU/l) and ICTP (3.2+/-0.1 ng/ml) levels returned similar to those recorded before treatment, while total BMD increased (+1.5+/-0.7, p<0.05), remaining however slightly lower than in basal conditions (-0.6+/-1.2, NS). In conclusion, our study shows that: a) acquired GHD in adulthood is associated with both normal bone formation/resorption indexes and normal total body BMD; b) GH therapy causes a significant rise of bone formation/resorption markers (earlier and greater for bone resorption); c) one-year GH therapy is associated with a reduction of total body BMD values, particularly evident in the first 6 months of treatment; d) the effects of GH therapy on bone turnover are transient, being completely reverted six months after the withdrawal of GH therapy; e) the increase of total body BMD (up to baseline values) after GH withdrawal might be explained as consequence of persisting effects of previous GH stimulation on bone remodeling.     

Impairment of adrenergic-induced proopiomelanocortin-related peptide release in heroin addicts

The effects of iv stimulation with clonidine on plasma levels of beta-lipotropin (beta-LPH), beta-endorphin (beta-EP), cortisol, growth hormone (GH) and adrenocorticotrophic hormone (ACTH) were tested in a group of 10 healthy volunteers and in 8 heroin abusers. Hormones were measured either by direct radioimmunoassay (RIA) (GH, cortisol) or after plasma extraction and Sephadex G-75 column chromatography (beta-LPH and beta-EP) or by immunoradiometric assay (IRMA) (ACTH). Plasma levels of GH increased in a similar fashion in the two groups. In the controls, clonidine induced release of beta-LPH and beta-EP after 30 min (from 8.9 +/- 1.0 to 19.1 +/- 4.6 fmol/ml, P less than 0.01 and from 8.1 +/- 0.6 to 17.9 +/- 4.6, P less than 0.01) and of ACTH after 60 min (from 12.1 +/- 1.8 to 18.1 +/- 1.8, P less than 0.05) while in addicts beta-EP but not beta-LPH showed a significant increase (from 8.5 +/- 0.7 to 19.8 +/- 4.2, P less than 0.05), 90 min after the injection. In heroin addicts, plasma cortisol levels decreased continuously after clonidine stimulation while in controls they showed a biphasic pattern, decreasing until the 60th min (from 135.2 +/- 30.4 ng/ml to 74.0 +/- 13.3, P less than 0.05) and regaining basal levels 1 h later (122.0 +/- 24.8, P less than 0.05 vs 60th min value). These data demonstrate the existence in human beings of noradrenergic control of proopiomelanocortin (POMC)-related peptides and indicate that chronic opiate abuse greatly interferes with this control. Clonidine-induced release of plasma beta-EP may be of importance with regard to its therapeutic effects in detoxification.     

PLASMA AND CYST FLUID LEVELS OF A5 AND A4 STEROID HORMONES IN WOMEN WITH GROSS CYSTIC BREAST DISEASE

delta 5 and delta 4 steroid levels were studied in the plasma and cyst fluid of women with gross cystic breast disease (GCBD). In luteal phase a significant increase in plasma levels (mean +/- SEM) of DHA (11.2 +/- 2.4 ng/ml), DHAS (1.45 +/- 0.6 micrograms/ml) and cortisol 277 +/- 15.7 ng/ml) was found; in follicular phase the mean levels were 4.09 +/- 0.47 ng/ml for DHA, 0.65 +/- 0.08 microgram/ml for DHAS and 190 +/- 46.3 micrograms/ml for cortisol. The DHA/DHAS and cortisol/androstenedione ratios were significantly higher in the plasma and lower in the cyst fluid of GCBD patients, than in the plasma of controls; the androstenedione/DHA ratio was higher in the cyst fluid than in the plasma of controls. The hormonal situation of the GCBD patients thus differed from that of the controls both in the plasma and cyst fluid, particularly as regards the delta 5 steroids.     

Growth hormone enhances follicle-stimulating hormone-induced differentiation of cultured rat granulosa cells

Suppression of serum GH levels in immature rats is associated with delayed onset of puberty and decreased ovarian steroidogenic responsiveness to FSH. To investigate possible direct effects of GH on the differentiation of ovarian cells, granulosa cells from hypophysectomized estrogen-treated rats were cultured with FSH in the presence or absence of GH for 3 days. FSH stimulated granulosa cell LH receptor formation and steroid production in a dose-dependent manner. Concomitant treatment with GH increased LH receptor content by enhancing the action of low doses of FSH without substantial increases in the maximal response. This increase was due to an elevation in the receptor number rather than changes in their affinity for hCG. At 3 ng/ml FSH, concomitant treatment with ovine or bovine GH increased LH/hCG binding in a dose-dependent manner, with 300 ng/ml GH increasing the FSH action by about 3-fold. LH receptors in the GH-treated cells were functional, as indicated by the enhanced cAMP production of these cells in response to LH treatment. The cellular protein content in the FSH-treated cultures was slightly increased by GH (18%), but cell number and viability were unaffected. The change in cell protein content could not account for the increases in the amount of LH receptors. In addition to its effects on LH/hCG receptor content, GH also augmented FSH-stimulated progesterone and 20 alpha-hydroxy-4-pregnen-3-one production in a dose-dependent manner, with 100 ng/ml GH causing significant increases in FSH-induced progesterone production. In contrast, GH treatment did not significantly affect FSH-stimulated estrogen production. The augmentating effects of GH on LH receptor formation and progestin biosynthesis were associated with an enhancement of FSH-stimulated cAMP production. In addition, GH increased forskolin- and 8-bromo-cAMP-induced LH receptor formation and progestin production. Thus, GH-augmented LH receptor induction and progestin biosynthesis may be due to both increased cAMP production and enhanced action of cAMP. The present data have demonstrated that GH augments gonadotropin-stimulated differentiation of ovarian granulosa cells, suggesting an important regulatory role of GH in follicular growth and pubertal development.     

Grwoth hormone, prolactin, and cortisol in dogs developing mammary nodules and an acromegaly-like appearance during treatment with medroxyprogesterone acetate

Concentrations of (GH) growth hormone, (PRI) prolactin, cortisol, progesterone, and (MPA) medroxyprogesterone acetate were determined by RIA in blood sera collected from beagle bitches 17 months after initiating treatment with MPA (75 mg/kg.3 months; n = 12) MPA vehicle (controls; n = 12), or progesterone implants which produced physiological levels of progesterone (13.8 + or - 2.1 ng/ml; n = 12). In the MPA-treated bitches, mean MPA levels were 104 + or - 6 ng/ml, mean GH levels were elevated (9.5 + or - 3.0 vs. 0.4 + or - 0.1 ng/ml; P 0.01); mean PRL levels were unchanged (13.7 + or - 2.8 vs. 12.6 + or - 1.2 ng/ml); and mean cortisol levels were suppressed (1.7 + or - 0.2 vs. 13.7 + or - 1.4 ng/ml; P 0.01) in comparison to those in control animals. None of these parameters was significantly affected by progesterone treatment. External signs of an acromegaly-like condition and large mammary gland nodules (diameters, 5 mm) were noted in, and limited to, 9 bitches with elevated ( 2.5 ng/ml) GH levels (12.8 + or - 3.0 ng/ml). These were 8 MPA-treated bitches which developed the acromegal-like condition during treatment and 1 progesterone-treated bitch which appeared acromegalic before treatment and in which the condition was considered to have developed spontaneously. The data suggest that the acromegaly-like changes and large mammary nodules in dogs administered the contraceptive progestin MPA occurred as a result of MPA-induced elevations in GH. The results do not preclude the possibility that the MPA-induced suppression of cortisol and/or the direct action of MPA on the mammary glands also contributed to mammary nodule formation. MPA-treated dogs may also provide a unique experimental model for studying chronic elevations in endogenous GH levels and for testing compounds for their ability to suppress GH levels.     

Regulation of growth hormone (GH) secretion by GH-releasing factor, somatostatin, and insulin-like growth factor I in ovine fetal and neonatal pituitary cells in vitro

Serum GH concentrations in the ovine fetus are much higher than those in the neonate, and the maximal GH response induced by GRF is 5-fold greater in the fetus than in the neonate. To clarify these in vivo observations further, we studied the effects of GRF, somatostatin (SRIF), and insulin-like growth factor I (IGF-I) on primary cultures of fetal and neonatal ovine pituitary cells. GH secretion from fetal ovine pituitary cells increased from 148 +/- 34 to 950 +/- 130 ng/10(5) cells.3 h in response to 1 nM GRF, whereas GH secretion from neonatal pituitary cells rose from 113 +/- 26 to 1221 +/- 129 ng/10(5) cells.3 h, a significantly greater response (P less than 0.001). This greater GRF-induced GH response in neonatal than fetal cells differs from the response in vivo and suggests that the increased in vivo response in the fetus is not due to inherently increased sensitivity of pituitary cells to GRF. SRIF (10 nM) decreased maximal GRF-induced GH secretion by 37 +/- 3% in fetal cells compared with 59 +/- 8% in neonatal cells (P less than 0.01). This may explain in part the decreased in vivo sensitivity to SRIF in the ovine fetus compared to that in the neonatal lamb. In fetal pituitary cells, 10 nM GRF increased ovine (o) GH mRNA from 100 +/- 14% to 145 +/- 40%, SRIF decreased oGH mRNA to 84 +/- 3%, and GRF and SRIF in combination increased fetal oGH mRNA to 126 +/- 24%. Values in neonatal pituitary cell cultures were similar (control, 100 +/- 17%; GRF, 132 +/- 6%, SRIF, 85 +/- 15%; GRF plus SRIF, 105 +/- 26%). Pretreating fetal cells with 100 nM IGF-I for 3 days reduced GRF-stimulated GH secretion from 1049 +/- 38 to 232 +/- 8 ng/10(5) cells.3 h (P less than 0.001). Similarly, IGF-I pretreatment of neonatal cells reduced GRF-stimulated GH secretion from 810 +/- 18 to 419 +/- 16 ng/10(5) cells.3 h (P less than 0.001). The mean secreted IGF-I was 0.58 U/ml (36 nM) in culture medium from neonatal cells and was unchanged by incubation for 3 days with 5 micrograms/ml hGH. Secreted IGF-I in medium from fetal cells was 0.87 U/ml (54 nM) without GH and 0.81 U/ml (51 nM) after incubation with human GH. IGF-I mRNA was present in neonatal pituitary and brain.(ABSTRACT TRUNCATED AT 400 WORDS)