Stress and the menstrual cycle: short- and long-term response to a five-day endotoxin challenge during the luteal phase in the rhesus monkey

Previously, we reported that in the rhesus monkey a 5-day inflammatory-like stress during the early-mid follicular phase acutely stimulates the hypothalamic-pituitary-adrenal axis and exerts effects on the hypothalamic-pituitary-gonadal axis, delays folliculogenesis and in some animals decreases luteal function in the post-treatment cycle. Because the endocrine environment at the time of the stress may influence the response to the stress, we now investigate the acute and long-term responses to a similar stress challenge during the luteal phase of the menstrual cycle, at a time of progesterone dominance. Nine monkeys with normal cycles were injected with endotoxin (lipopolysaccharide; LPS, 150 microg i.v.) twice a day for 5 days starting on days 4-8 after the LH peak. Blood samples were taken at hour 3 and hour 8 after each morning LPS injection to monitor the acute gonadotropin and cortisol responses. To verify cyclicity, menses were checked every day, and daily blood samples were taken for estradiol and progesterone measurement. Two control cycles, the LPS treatment cycle, and two post-treatment cycles were documented. Endotoxin activated the adrenal axis: mean (+/-SE) cortisol secretion was significantly increased at hour 3 after the first morning LPS injection (74.1 +/- 4.9 vs. 24.1 +/- 1.8 microg/dL in the control; P < 0.05) and remained elevated at hour 8. This response decreased progressively with time: on day 5 of LPS treatment, the cortisol level was still significantly higher than control at hour 3 (38.5 +/- 5.0 microg/dL; P < 0.05) but had returned to the control concentration by hour 8 (days 3-5 of LPS). Mean integrated progesterone through the luteal phase of the LPS treatment cycle was significantly decreased (33.5 +/- 3.3 ng/ml vs. 48.9 +/- 3.7 and 54.0 +/- 4.9 in the two control cycles; P < 0.05), but luteal phase length remained unchanged. When compared with control levels on the same day of the luteal phase, about one third of LH and FSH values were lower than one SD below mean control levels. LPS administration had no effect on the two post-treatment cycles, except that integrated luteal progesterone in 3 out of 9 monkeys was still reduced in post-treatment cycle 1. There were no differences in follicular phase length and preovulatory estradiol peaks between control cycles and post-treatment cycles. When compared with our previous study, the results illustrate specific responses to stress at different phases of the menstrual cycle and support the notion that a moderate short-term inflammatory-like stress episode has the potential to subtly alter critical aspects of cyclicity.     

Inadequate luteal function is the initial clinical cyclic defect in a 12-day stress model that includes a psychogenic component in the Rhesus monkey

As part of our goal to develop nonhuman primate models to prospectively study how different types of stress may affect the menstrual cycle, we have investigated whether a short-term stress challenge that includes a significant psychogenic component can induce cyclic dysfunction. The study was performed in rhesus monkeys. The stress challenge had several components that included the psychological response to both a tethering system and to a simultaneous move to an unfamiliar environment and the response to the short surgical procedures required to install and disconnect the tethering system. The stress challenge lasted for 12 d and was initiated in the follicular (n = 5) or luteal (n = 6) phase of the menstrual cycle. At the end of the stress period, the tethering system was removed, and the animal was returned to its regular housing. To monitor cyclicity, FSH, LH, E2, and progesterone were measured daily throughout the two preceding control cycles, the experimental cycle, and the two poststress cycles, whereas the adrenal endocrine axis response was monitored by measuring cortisol. Animals remained ovulatory after the short-term stress; however, integrated progesterone secretion in the luteal phase (from the day of LH surge +1 to the day of menstruation -1) of the stress cycle was significantly decreased by 51.6% when the stress was initiated in the follicular phase and by 30.9% when it started in the luteal phase. Lower integrated LH levels (luteal d 5-13) accompanied the decreased progesterone. Cyclic parameters were still abnormal in the first poststress cycle, such as a prolonged follicular phase after a stress in the preceding follicular phase or inadequate luteal function after a stress in the preceding luteal phase. Within 4 h of the stress, there was a rapid 3-fold increase in cortisol levels over controls. Levels decreased progressively thereafter but remained significantly higher than controls during the entire short-term stress period. They were still significantly higher in the first 2 wk after stress. Overall, the data suggest that secretory inadequacy of the corpus luteum represents a first clinical stage in the damage that stress can inflict on the normal menstrual cycle. Of interest is the observation that this limited 12-d stress, which includes a significant psychogenic component, continues to produce detrimental effects on the menstrual cycle past the period during which it is exerted. Significant decreases in integrated luteal LH values in the poststress cycle suggest that these effects may be related to continuing disturbances in the neuroendocrine component of the reproductive axis.     

Expression and role of the corticotropin-releasing hormone/urocortin-receptor-binding protein system in the primate corpus luteum during the menstrual cycle

CRH/urocortin-receptor-binding protein (CRH/UCN-R-BP) mRNAs are dynamically expressed in the primate ovary during the menstrual cycle. Therefore, studies were designed to localize CRH/UCN-R-BP mRNAs to ovarian cell types, quantitate protein expression during the corpus luteum (CL) lifespan, and investigate the role of this system in the macaque ovary at midcycle. Monkey ovaries were removed during the preovulatory phase and through the luteal phase to localize CRH/UCN-R-BP mRNAs by in situ hybridization and determine their protein levels in CL by Western blotting. Also, vehicle or a CRH receptor antagonist (astressin) was injected into the preovulatory follicle; daily serum samples were analyzed for hormone levels, and ovaries were removed on d 9 of the luteal phase for histological analysis. There was minimal ligand mRNA staining, whereas receptor and CRHBP was detected in the granulosa and theca cells of the preovulatory follicle. However, ligand and receptor mRNA staining was appreciable in luteal cells of the CL during the early luteal phase (ECL) and diminished in the late luteal phase (LCL). CRHBP staining was low in the ECL and increased markedly in the LCL. Ligand and receptor protein expression was also highest during ECL, whereas CRHBP expression was highest at the LCL. Although astressin injection did not prevent follicle rupture, progesterone levels were significantly less by the mid-luteal phase, and estradiol levels never increased above baseline during the CL lifespan. Histological indices of cell degeneration were observed in the astressin-treated CL. Thus, CRH/UCN-R-BP components are expressed in an ovarian cell-specific manner. The expression pattern and results from antagonist injection are consistent with the hypothesis that CRH/UCN-R activation promotes luteal development and/or structure-function in monkeys during the menstrual cycle.     

Effect of reduced luteinizing hormone concentrations on corpus luteum function during the menstrual cycle of rhesus monkeys

To further define the relationship between plasma LH concentrations and progesterone secretion by the primate corpus luteum, we examined luteal function in rhesus monkeys in response to reduced LH concentrations during the luteal phase of the menstrual cycle. Five anovulatory rhesus monkeys received a pulsatile infusion of synthetic GnRH (6 micrograms/pulse; one pulse per h, iv) to restore menstrual cyclicity. During the early luteal phase (4-5 days after ovulation), the amount of GnRH administered per pulse was reduced to 1/250th or 1/750th of the standard GnRH infusion regimen. Plasma LH concentrations, determined by bioassay, were reduced by approximately 50% during cycles maintained by reduced GnRH concentrations compared with the standard GnRH dosage. Serum progesterone concentrations were maintained for 5-6 days after GnRH reduction and declined thereafter, and premature menstruations were observed in four of seven cycles maintained by the 1/250th GnRH reduction and four of six cycles maintained with the 1/750th GnRH reduction. These results are consistent with the hypothesis that luteal regression during the nonfertile menstrual cycles of primates is due primarily to an alteration in luteal cell responsiveness to LH, rather than a reduction in the gonadotropic drive to the corpus luteum per se. When plasma LH concentrations were reduced during the early luteal phase to values below those found during the onset of luteal regression in control cycles, luteal function was maintained for 5-6 days. However, as the luteal phase progressed, the reduced LH concentrations were unable to sustain progesterone secretion, and premature menses occurred in some, but not all, animals.     

Is the decrease in the hypophysiotropic signal frequency normally observed during the luteal phase important for menstrual cyclicity in the primate?

The two phases of the ovulatory menstrual cycle of the primate are characterized by divergent activities of the GnRH pulse generator. During the luteal phase, LH pulse frequency is significantly reduced below that observed during the follicular phase. In this report we investigate whether the decrease in pulse frequency during the luteal phase is of physiological relevance to normal menstrual cyclicity. We have tested the effect of a pulsatile GnRH infusion given iv at hourly intervals for a period of 8-10 days during the luteal phase on the subsequent three to five cycles in eight female rhesus monkeys. Three of the eight animals received two treatment courses. Amounts of GnRH infused were 1.5 micrograms/pulse (n = 2 trials); 3.0 micrograms/pulse (n = 7); and 4.0 micrograms/pulse (n = 2). LH response to GnRH pulses of 1.5 and 3.0 micrograms resembled spontaneous LH pulses observed during the luteal phase. During the GnRH infusion period, the monkeys were fitted with a primate vest and tethered. Eleven control experiments were performed in these monkeys under similar conditions. GnRH therapy during the luteal phase affected subsequent cycles significantly, while no differences were observed in the control experiments. Overall mean follicular phase length in the control cycle was 13.4 days; it was significantly increased (P less than 0.005) in all post-GnRH treatment cycles to reach 34.4 (+/- 10.9), 43.9 (+/- 12.7), 40.4 (+/- 13.0), and 23.1 (+/- 4.8) days (+/- SE) in the first to fourth post-GnRH cycles, respectively. Progesterone secretion was significantly lower (P less than 0.05) in the first two post-GnRH cycles than in the control cycles: progesterone, 46.4 (+/- 2.1) in all control cycles, decreased to 27.7 (+/- 3.7), 24.8 (+/- 4.3), 34.0 (+/- 5.4), and 32.0 (+/- 6.5) surface units (+/- SE) from the first to fourth post-GnRH cycles, respectively, while luteal phase length remained relatively unchanged. The data indicate that significant disturbances in the menstrual cycle of the rhesus monkey follow imposed changes in the normal frequency pattern of the GnRH hypophysiotropic signal during the luteal phase and suggest that the naturally occurring slowing of GnRH-LH pulse frequency during the luteal phase is a relevant phenomenon in the sequence of events which control menstrual cyclicity.     

Astressin B, a nonselective corticotropin-releasing hormone receptor antagonist, prevents the inhibitory effect of ghrelin on luteinizing hormone pulse frequency in the ovariectomized rhesus monkey

Administration of ghrelin, a key peptide in the regulation of energy homeostasis, has been shown to decrease LH pulse frequency while concomitantly elevating cortisol levels. Because increased endogenous CRH release in stress is associated with an inhibition of reproductive function, we have tested here whether the pulsatile LH decrease after ghrelin may reflect an activated hypothalamic-pituitary-adrenal axis and be prevented by a CRH antagonist. After a 3-h baseline LH pulse frequency monitoring, five adult ovariectomized rhesus monkeys received a 5-h saline (protocol 1) or ghrelin (100-microg bolus followed by 100 microg/h, protocol 2) infusion. In protocols 3 and 4, animals were given astressin B, a nonspecific CRH receptor antagonist (0.45 mg/kg im) 90 min before ghrelin or saline infusion. Blood samples were taken every 15 min for LH measurements, whereas cortisol and GH were measured every 45 min. Mean LH pulse frequency during the 5-h ghrelin infusion was significantly lower than in all other treatments (P < 0.05) and when compared with the baseline period (P < 0.05). Pretreatment with astressin B prevented the decrease. Ghrelin stimulated cortisol and GH secretion, whereas astressin B pretreatment prevented the cortisol, but not the GH, release. Our data indicate that CRH release mediates the inhibitory effect of ghrelin on LH pulse frequency and suggest that the inhibitory impact of an insufficient energy balance on reproductive function may in part be mediated by the hypothalamic-pituitary-adrenal axis.     

GONADOTROPHIN SECRETION IN THE SECOND HALF OF THE MENSTRUAL CYCLE: A COMPARISON OF WOMEN WITH NORMAL CYCLES, LUTEAL PHASE DEFECTS AND DISTURBED FOLLICULAR DEVELOPMENT

In order to study the relationship between episodic gonadotrophin secretion and alterations of ovarian hormone secretion, we examined women with normal menstrual cycles (n = 26), luteal phase defects (n = 10) or disturbed follicular oestradiol secretion (n = 8) as established by daily (except weekends) determinations of oestradiol and progesterone. Pulsatile gonadotrophin secretion was studied during the luteal phase or the second half of the menstrual cycle sampling at 15 min intervals for 12 h. LH and FSH mean concentrations and LH pulse frequency were significantly (P less than 0.01) increased in the group with disturbed follicular development in the presence of decreased oestradiol (E2) and progesterone (P4) levels. In women with luteal phase defects mean LH and FSH concentrations and pulsatile LH secretion showed a nonsignificant trend to lower values in the presence of significantly decreased P4 concentrations during the luteal phase.     

Tiapride-induced chronic hyperprolactinaemia: interference with the human menstrual cycle.

Four regularly menstruating volunteers were submitted to an oral treatment, for 3 consecutive cycles and starting on the first day of a cycle, with tiapride at daily doses ranging from 1 x 100 mg to 2 x 100 mg. The first and the last cycle under treatment, as well as a prior control cycle, were thoroughly studied by means of daily measurements of blood concentrations of LH, FSH, prolactin (PRL), oestradiol and progesterone. Tiapride, a benzamide derivative with dopaminergic blocking activity at the level of the lactotrophes, increased mean PRL secretion in each subject but a permanent hyperprolactinaemia above 700 uU/ml was attained only in one subject. Despite these widely fluctuating PRL levels in most subjects, the resulting overall hyperprolactinaemia induced in all cases a progressive deterioration of the function of the corpus luteum: 5 cycles showed luteal phases reduced by 2--5 days, one cycle was characterized by some slight luteinisation but questionable ovulation and the 2 remaining cycles were anovulatory. The interruption of drug intake one week after the onset of menses led thereafter to a cycle with a likely inadequate luteal phase but of normal length. It is concluded that even a non-permanent hyperprolactinaemia can impair the normal function of the hypothalamo-pituitary-ovarian axis, as well as exhibit some effects in a cycle consecutive to the normalization of PRL. With the exception of the impaired luteal progesterone secretion, the pooled hormonal data from the short luteal phase cycles under tiapride-induced hyperprolactinaemia exhibit very little significant differences, as compared to the corresponding values in the control cycles. Some delay in the onset of follicular maturation, however, should be assumed since the follicular phase had been lengthened by 1 to 31 days in 5 of the 6 cycles with luteinisation during treatment. The present results are compatible with a double impact -- both at the ovarian and the hypothalamo-pituitary levels -- of hyperprolactinaemia in its mechanisms of impaired function of the hypothalamo-pituitary ovarian axis.     

Follicular fluid treatment during the follicular versus luteal phase of the menstrual cycle: effects on corpus luteum function

Administration of charcoal-extracted porcine follicular fluid (pFF) to rhesus monkeys at the time of menses impairs the subsequent function of the corpus luteum of the menstrual cycle. The following studies were performed: 1) to characterize the luteal phase defect induced by pFF treatment at menses, and 2) to determine whether pFF treatment in the luteal phase alters corpus luteum function. Adult, female rhesus monkeys were injected sc for 3 days with pFF (10, 5, and 5 ml) beginning on day 1 (n = 5) or day 18 (n = 4) of the menstrual cycle. Femoral venous blood was collected daily throughout the treatment cycle and during the posttreatment cycle of day 18 to 20-treated monkeys. Serum LH, FSH, 17 beta-estradiol (E2), and progesterone (P) were measured by RIA. After pFF treatment on days 1-3, FSH and E2 levels in the early follicular phase were less (P less than 0.05) than those of control cycles (n = 7). Serum LH was not suppressed by pFF treatment. Moreover, the preovulatory rise in circulating E2 and the amplitude of the LH/FSH surge were similar in control and pFF-treated monkeys. Although timely midcycle gonadotropin surges occurred in four of five pFF-treated monkeys, serum P was markedly reduced (P less than 0.05) during the first half of the luteal phase. Circulating P increased to control levels during the late luteal phase before normal onset of menses 16.3 +/- 1.0 (SE) days after the LH surge. Treatment with pFF on days 18-20 of the cycle reduced the levels of circulating FSH, but serum LH, E2, P, and the length of the luteal phase remained comparable to control cycles. Moreover, the hormonal patterns and the length of the follicular and luteal phases in the posttreatment cycle indicated normal ovarian function. Thus, pFF treatment at menses results in an aberrant ovarian cycle characterized by an insufficient, rather than short, luteal phase. Whereas pFF treatment in the early follicular phase vitiates development of the dominant follicle and the related corpus luteum, similar treatment at midluteal phase does not suppress concurrent luteal function or subsequent folliculogenesis.     

PROLACTIN LEVELS DURING THE MENSTRUAL CYCLE*

The levels of prolactin, FSH, LH, oestradiol and progesterone were measured daily during fourteen ovulatory cycles. The behaviour of FSH, LH, oestradiol and progesterone was classical. Non-systematic changes occurred in prolactin levels during the course of the menstrual cycle with the highest level being either during the ovulatory period or during the luteal phase. However, the mean level of prolactin was significantly higher during the ovulatory and luteal phases than during the follicular phase. A direct relationship between oestradiol and prolactin levels was noted, although there was no correlation between prolactin on the one hand and FSH, LH and progesterone on the other.     

Exercise induces two types of human luteal dysfunction: confirmation by urinary free progesterone

We have previously reported that during 2 months of strenuous exercise, untrained young women with documented ovulatory menstrual cycles developed secondary oligoamenorrhea and luteal phase defects. In this study we tested the hypothesis that such abnormalities arise by altered neuroendocrine regulation of menstrual hormone secretion and that weight loss potentiates such effects. We supply a detailed analysis of the 20 cycles, of the total of 53, in which luteal phase abnormalities occurred. During the control month and 2 exercise months, all subjects collected daily overnight urine samples for the determination of LH, FSH, estriol (E3), and free progesterone (P) excretion by RIAs and creatinine by chemical assay. The characteristics of the abnormal luteal phase cycles were determined by comparing the excreted hormone levels and patterns during the control cycles with those of exercise cycles. The area under the curve (AUC) for each hormone was calculated for the follicular and luteal phases of each cycle. Six of the exercise cycles exhibited an inadequate luteal phase. This was characterized by a mean integrated P area of 202.4 (SEM, -61.8) nmol/day.nmol creatinine, compared with 331.7 (SEM, 64.7) during the corresponding control cycles, over a period of 9 or more days after the urinary LH peak to the onset of menses. Fourteen of the exercise cycles exhibited a short luteal phase. This was characterized by a mean integrated P area of 75.9 (30.9) nmol/day.nmol creatinine, compared to 267 (61.7) during the corresponding control cycles, over a span of 8 days or less from the urinary LH peak to the onset of menses. Additional abnormalities occurred only in the short luteal phase cycles. These included an increase in the length and AUC for E3 of the follicular phase and a decrease in the AUC of LH during the luteal phase. We conclude that the initiation of strenuous endurance training in previously ovulating untrained women frequently leads to corpus luteum dysfunction associated with insufficient P secretion and, in the case of short luteal phase cycles, decreased luteal phase length. That exercise may alter the neuroendocrine system is suggested by a delay in the ovulatory LH peak in spite of increased E3 excretion; moreover, less LH is excreted during the luteal phase. The lack of positive feedback to estrogens and decreased LH secretion during the luteal phase could compromise corpus luteum function. In contrast, decreased free P excretion was the sole abnormality noted in menstrual cycles with an inadequate luteal phase.     

Relationship between symptom severity and hormone changes in women with premenstrual syndrome

The relationship between symptoms and plasma hormone levels was investigated during 2 consecutive cycles in 18 women with the premenstrual tension syndrome (PMS). The women were asked to provide daily symptom ratings using a previously described and tested rating scale, and blood samples were taken daily during the luteal phase and most of the follicular phase for plasma estradiol, progesterone, FSH, and LH measurements. The symptom scores during the premenstrual phase were compared within each woman and between cycles with higher luteal phase and cycles with lower luteal phase plasma estradiol, progesterone, FSH, and LH concentrations. The results indicated that higher adverse premenstrual scores occurred in cycles with high luteal phase plasma estradiol and progesterone concentrations. In particular, a high luteal phase plasma estradiol concentration was related to higher premenstrual scores for adverse symptoms and lower scores for positive mood symptoms. The women experienced more severe PMS in cycles with high luteal phase plasma estradiol and progesterone levels. The results contradict the hypothesis that progesterone deficiency plays a part in the etiology of PMS.     

Hormonal pattern of adolescent menstrual cycles.

Serum FSH, LH, PRL, estradiol, pregnenolone, progesterone, 17-hydroxyprogesterone, androstenedione, testosterone, 5 alpha-dihydrotestosterone, and androsterone were measured radioimmunologically in 20 normal girls aged 13-17 yr. Samples were taken every day or every second day during one menstrual cycle. The cycles recorded could be divided into three groups. The first and oldest group consisted of 10 girls with a mean gynecological age (years since menarche) of 2.9 yr. The luteal phase was at least 11 days and the progesterone concentration was at least 5 ng/ml. The testosterone rise (mean, 55%) on the day of LH surge correlated well with the simultaneous progesterone rise (mean, 270%) and the following luteal progesterone secretion. A negative correlation was seen between the FSH concentration on days 3-4 of the cycle and the length of the follicular phase. The second group consisted of 4 girls who had a mean gynecological age of 1.5 yr. The luteal phase was of 4- to 8-day duration and the progesterone secretion was lower than in group I. The follicular phase testosterone concentration was lower in group II as compared to group I. No "periovulatory" testosterone increases were seen, although every cycle displayed an LH and FSH peak. The third group consisted of 6 girls with a mean gynecological age of 1.1 yr. These cycles were anovulatory, as the serum progesterone concentration never exceeded 1.0 ng/ml. In two cycles, signs of follicular maturation were seen. In the four others, the androgen levels tended to be elevated. In two cases, the testosterone and androstenedione concentrations were 2-4 times elevated from the beginning of these two cycles. Thus, the hormonal pattern of adolescent menstrual cycles is far from uniform. It is very likely that in addition to gonadotropins, estradiol and progesterone, androgens may also have a role in the development and maintenance of normal menstrual function in the female.     

The effect of luteal phase estrogen antagonism on luteinizing hormone pulsatility and luteal function in women

Pulsatile LH secretion was studied to determine if the frequency of LH pulses was altered by the administration of clomiphene citrate (CC; 150 mg) for 5 days during the midluteal phase of the menstrual cycle. Seven normal women received CC or placebo in alternate cycles in a randomized double blind fashion. On the day after drug administration, blood samples were obtained at 15-min intervals for 8 h for serum LH determinations. Daily blood samples were also obtained throughout the luteal phase for determination of serum LH, estradiol (E2), and progesterone. LH pulse frequency increased from 2.4 +/- 0.5 (+/- SEM)/8 h after placebo to 3.9 +/- 0.6/8 h (P less than 0.01) after CC treatment, but pulse amplitude did not change. The transverse mean of serum LH was higher after CC (13.6 +/- 0.5 mIU/ml) than after placebo (8.4 +/- 0.3 mIU/ml; P less than 0.001), and luteal phase length was increased from 13.5 +/- 0.5 to 16.0 +/- 0.4 days (P less than 0.001) by administration of CC. Luteal phase levels of E2 and progesterone measured daily were significantly elevated (P less than 0.01) in CC-treated cycles. These findings suggest that CC increases the frequency of hypothalamic GnRH secretory episodes, perhaps by an action involving a decrease in endogenous opioid peptide activity. Since peripheral progesterone levels were elevated in the CC-treated cycles, E2 may play a permissive role in the ability of progesterone to increase endogenous opioid peptide activity acutely. Furthermore, since the luteal phase was significantly prolonged by an increase in endogenous LH pulse frequency, the slow frequency of LH pulses in the normal late luteal phase may contribute to the onset of luteolysis in the human.     

Inhibin concentrations throughout the menstrual cycles of normal, infertile, and older women compared with those during spontaneous conception cycles

Plasma immunoreactive inhibin levels have been measured in a series of normal conception cycles (group I; n = 7), and the data compared to inhibin concentrations in normal menstrual cycles (group II; n = 8), in women with luteal phase defects (group III; n = 7), and in women in the perimenopausal period (group IV; n = 6). Daily plasma levels of LH, FSH, progesterone, estradiol, and inhibin were determined in each subject, and daily mean profiles for each hormone in each subject group were calculated and expressed as geometric means with 68% confidence limits. During the follicular and early luteal phases, inhibin concentrations in the normal nonpregnant group (group II) were significantly higher than those in the conception cycles of group I, but after implantation in the conception cycles, inhibin concentrations increased to levels in excess of those seen at any time in nonconception cycles (716-1352 U/L; P less than 0.02). The postimplantation rise in inhibin did not initially appear to follow the same pattern as progesterone. While progesterone concentrations rose within 24 h of the first detectable increase in hCG, inhibin levels did not increase until 3 days later, although after this point concentrations increased serially and in parallel with progesterone. LH and FSH concentrations were markedly suppressed after implantation. Follicular and early luteal inhibin concentrations in cycles with luteal phase defects were also higher than those in conception cycles, although this difference was only significant in the midfollicular phase. Follicular phase inhibin concentrations in cycles from older women (group IV) were lower than those in groups II and III, but were not distinguishable from those in the conception cycles. Estradiol concentrations in the same subjects were significantly lower during the early follicular phase, while follicular and luteal FSH concentrations were significantly higher than those during conception cycles. Finally, examination of the relationship between inhibin, FSH, and estradiol around menstruation in the older women revealed a far closer temporal association between FSH and estradiol than between FSH and inhibin. In conclusion, inhibin concentrations rise and fall throughout the human menstrual cycle in a manner that is similar to but at specific times significantly different from that of either of the ovarian steroids estradiol and progesterone. It is considered to be a peptide of granulosa cell origin and may be an indicator of the size of the follicular pool during the early stage of the cycle. However, although there is some degree of inverse correlation between profiles of inhibin and profiles of FSH, this relationship is not particularly clear.(ABSTRACT TRUNCATED AT 400 WORDS)     

GONADOTROPHINS, OESTRADIOL AND PROGESTERONE DURING THE MENSTRUAL CYCLE IN BULIMIA NERVOSA

Gonadotrophins and gonadal hormones were studied during the menstrual cycle or during 5 weeks when no cycles occurred in 15 patients who were diagnosed as having bulimia by DSM III criteria. Nine healthy age-matched women served as controls. Based on plasma oestradiol (E2) values patients were divided into two groups. Group I (n = 8) did not show E2 increases greater than 444 pmol/l indicating that no follicular development took place. Group II showed normal follicular hormone production during the follicular phase but impaired progesterone (P4) levels during the luteal phase. Studies of episodic gonadotrophin secretion during the follicular phase revealed low average LH and FSH values and reduced amplitude but no significant changes of frequency in group I. Our data indicate that impaired follicular maturation as seen in about half of the bulimic patients is caused by impaired gonadotrophin secretion.     

Effects of metoclopramide-induced hyperprolactinemia during early follicular development on human ovarian function

Nine healthy women, aged 25 to 36 yr, were treated with metoclopramide (MC) (10 mg orally three times daily) from the first to the sixth day of their cycle (treatment A) for two successive cycles (n = 18) and six of these women later received MC from -3 to the fifth day of the menstrual cycle (treatment B) during one or two cycles (n = 10), to investigate the effects of hyperprolactinemia during the early phase of ovarian follicular growth. Comparisons were performed with control cycles in the same women. The treatment cycles were characterized by low serum concentrations of LH during the early follicular phase and at midcycle, low early follicular phase serum testosterone (T) levels and high luteal phase T and free T index values, with no significant differences between A and B treatment modalities. We classified the treatment cycles into two categories, seriously disturbed and normal or only slightly disturbed, on the basis of ultrasonographic findings and midcycle estradiol (E2) and luteal phase progesterone (P) concentrations. Folliculogenesis was seriously disturbed in 11 of the 28 treatment cycles (39%). During these cycles, midcycle serum LH and the LH to FSH ratio were lowered, luteal phase LH and FSH increased, midcycle E2 and luteal phase P and the P to E2 ratio decreased, luteal phase T and the free T index and androstenedione increased, and luteal phase 5 alpha-dihydrotestosterone decreased. During the early follicular phase and at midcycle the ratios of T to E2 and androstenedione to E2 were increased, and at midcycle and during the luteal phase of the cycle the ratio of T to 5 alpha-dihydrotestosterone was increased. These changes in steroid hormones were probably of ovarian origin since the serum concentrations of dehydroepiandrosterone sulfate and sex hormone-binding globulin were similar in seriously disturbed and control cycles. Four of the nine study subjects were hyperprolactinemia sensitive (disturbed folliculogenesis) and five hyperprolactinemia resistant (no disturbance in folliculogenesis). During the control cycles the hyperprolactinemia-sensitive women had significantly higher serum concentrations of T than the other women. The present observations indicate that hyperprolactinemia may impair the development of the ovarian follicles during their recruitment period, especially in women with relatively high serum T levels.     

Suppression of luteal function by a luteinizing hormone-releasing hormone antagonist during the early luteal phase in the stumptailed macaque monkey and the effects of subsequent administration of human chorionic gonadotropin

In previous studies a single sc injection of the LHRH antagonist [N-Ac-D-Nal(2)1,D-pCl-Phe2,D-Trp3,D-hArg(Et2)6,D-Ala10 ]LHRH during the luteal phase of the stumptailed macaque menstrual cycle caused a transient suppression of serum LH and progesterone concentrations. To investigate whether a more prolonged suppression of LH release during the early luteal phase could result in a sustained suppression of progesterone, 10 monkeys were treated with 3 consecutive daily injections of 300 micrograms LHRH antagonist/kg beginning on days 0 (n = 2), 1 (n = 1), 2 (n = 1), 3 (n = 2), 4 (n = 2), and 5 (n = 2) after the LH surge. When the antagonist was administered on the day of the LH surge, serum concentrations of bioactive LH were still elevated on the following day, but then fell to low levels. Serum progesterone concentrations were subnormal in these monkeys for the next 10 days, but recovered toward the late luteal phase. In the 8 monkeys receiving antagonist starting between days 1-5 after the LH surge, serum concentrations of bioactive LH were suppressed to near the detection limit of the assay for 4 days after the first injection. Seven of the 8 monkeys demonstrated a progressive decline in serum progesterone concentrations to undetectable values which remained for the duration of the luteal phase. In the remaining monkey the decline in progesterone was less marked; this animal presented a normal progesterone profile 3 days after the last antagonist injection. Premature menses occurred in all 8 monkeys; the next ovulation occurred 18.9 +/- 0.3 days after the last antagonist injection. To test luteal function after antagonist treatment during the early luteal phase and to mimic the rescue of the corpus luteum during a fertile cycle and assess the contraceptive effects of antagonist, hCG in daily doses of 30, 60, 90, 180, and 360 IU was administered starting on day 7 of the luteal phase to monkeys previously treated with three daily injections of 300 micrograms antagonist/kg during the early luteal phase. Control monkeys received hCG injections alone. In the controls, hCG administration elevated serum progesterone concentrations to 15-20 ng/ml. In three monkeys in which antagonist administration did not commence until day 5 or 6, hCG overcame the suppressive effect of the antagonist. However, in seven monkeys in which antagonist administration began on days 1-4, hCG caused only a small progesterone rise (maximal range, 1.8-4.9 ng/ml), about 20% of that observed in control monkeys receiving hCG.(ABSTRACT TRUNCATED AT 400 WORDS)     

Immunoreactive inhibin concentrations in serum throughout the menstrual cycle of the macaque: suppression of inhibin during the luteal phase after treatment with an LHRH antagonist

Concentrations of immunoreactive inhibin in serum samples collected daily from six adult stumptailed female macaques during normal menstrual cycles were measured with a heterologous radioimmunoassay. Serum inhibin concentrations were low during the follicular phase of the cycle. After ovulation they began to rise, reaching a plateau between 8 and 11 days, before falling in parallel with the decline in luteal progesterone secretion. The dependence of the inhibin secretion by the corpus lutem on pituitary gonadotrophins was investigated by the administration of an LHRH antagonist [N-Ac-D-Nal(2)1,D-pCl-Phe2,D-Trp3,D-hArg(Et2)6,D-Ala10 ]LHRH once daily for 3 days beginning on day 8 of the luteal phase in six macaques. LHRH antagonist treatment markedly suppressed serum levels of inhibin and progesterone and these remained at the level found in the follicular phase for the remainder of the luteal phase. These results show that inhibin in the macaque is secreted into the peripheral blood almost exclusively during the luteal phase, being highest when FSH is at its nadir. Suppression of serum inhibin concentrations during the luteal phase by LHRH antagonist suggests that its secretion is integrated with the LH control of the corpus luteum.     

Dynamic expression and regulation of the corticotropin-releasing hormone/urocortin-receptor-binding protein system in the primate ovary during the menstrual cycle

CONTEXT: Microarray analysis discovered that mRNA for CRH-binding protein (CRHBP) increased significantly in the primate corpus luteum (CL) after LH withdrawal. OBJECTIVE: Our objective was to determine whether other components of the CRH/urocortin-receptor-binding protein (UCN-R-BP) system are expressed in the CL during the menstrual cycle and regulated by LH. DESIGN: CL were collected from monkeys during the early (d 3-5 after the LH surge) to very late (d 18-19) luteal phase and from controls or animals receiving GnRH antagonist (Antide, 3 mg/kg body weight). CRH/UCN-R-BP system components were quantitated for mRNA levels by real-time PCR and analyzed for protein localization by immunohistochemistry. RESULTS: All genes encoding the CRH/UCN-R-BP system, except for UCN3, were expressed in the CL. CRH mRNA levels did not change during the luteal phase, whereas expression of UCN, UCN2, CRHR1, and CRHR2 was maximal at early or mid luteal phase before declining (P < 0.05) at the later stages. CRHBP mRNA levels were lowest at mid and increased (P < 0.05) in the late luteal phase. Suppressing gonadotropin secretion reduced UCN2 (P < 0.05) and increased CRHBP (P < 0.05) mRNA levels, without altering the expression of other ligands or receptors. CRH, UCN, UCN2 and their receptors were localized to the granulosa-lutein cells of the CL, whereas CRHBP was limited to the theca and theca-lutein cells of the preovulatory follicle and CL. CONCLUSIONS: A local CRH/UCN-R-BP system exists in the macaque CL that is dynamically expressed and LH regulated during the luteal phase of the menstrual cycle. Ligand-receptor activity may regulate luteal structure-function, at this point in an unknown manner, in primates.