Winfried G. Rossmanith

The impact of ovarian laser surgery on the gonadotrophin secretion in women with polycystic ovarian disease

To evaluate the effects of ovarian surgery on the deranged episodic gonadotrophin release of women with the poly‐cystic ovarian disease (PCOD), we studied 11 patients with the clinical and endocrinological features of PCOD before and after Iaparoscopic laser coagulations of ovarian surfaces and cysts. During both occasions, blood was collected at 15‐min intervals for 8 h to determine LH and FSH secretory profiles and additionally for 3 h during GnRH Injections (25 pg twice within 2 h) to assess pituitary responsiveness. Serum testosterone, androstendione and oestrogen (oestrone, oestradlol) levels were markedly reduced (P > 0·05 or less) after surgery. Mean LH concentrations declined (P > 0·001), while FSH levels Increased (P > 0·01) following laser treatments. The LH pulse frequencies (by Cluster analysis) did not change after ovarian surgery, but the LH pulse amplitudes were markedly reduced (P > 0·01). Lower (P > 0·05 or less) LH concentrations were attained in response to GnRH challenges, and the stimulated FSH release also tended to decrease after laser treatments. Thus, ovarian surgery In PCOD women resulted in reduced serum sex steroid concentrations and In divergent effects on serum LH and FSH levels. The attenuated pituitary LH responsiveness after ovarian surgery suggests action of sex steroids primarily at the pituitary site, while the Increase In FSH concentrations may be attributed to other factors selectively modulating FSH release.

The Distribution of Progesterone Receptor Immunoreactivity and mRNA in the Preoptic Area and Hypothalamus of the Ewe: Upregulation of Progesterone Receptor mRNA in the Mediobasal Hypothalamus by Oestrogen

The distribution of progesterone receptors (PR) was mapped in the hypothalamus of the ewe using immunocytochemistry. These results were confirmed using in situ hybridization with a sheep‐specific 35S‐labelled riboprobe. In addition, the effect of oestrogen on the level of PR mRNA in the hypothalamus was examined in ovariectomized (OVX) ewes following treatment with an oestrogen implant or without treatment. PR immunoreactive (‐ir) cells were readily detected in OVX animals. Labelled cells were observed in four main hypothalamic regions: the preoptic area (POA), including the organum vasculosum of the lamina terminalis, periventricular nucleus (PeVN), ventromedial nucleus (VMN) and the arcuate nucleus (ARC) (including the region ventral to the mamillary recess). In addition, lightly stained PR‐ir cells were observed in the supraoptic nucleus and a few PR‐ir cells were also found in the diagonal band of Broca. No PR‐ir cells were found in the brainstem. PR mRNA‐containing cells were found in the same hypothalamic regions as the PR‐ir cells. Image analysis of emulsion‐dipped slides following in situ hybridization indicated that oestrogen treatment increased (P<0.01) the mean number of silver grains/cell and the density of labelled cells in the VMN and ARC but had no effect on the level of PR mRNA expression in the POA or PeN. The distribution of PR‐containing cells in the hypothalamus is similar to that described in other species and all cells were located in nuclei that contain large populations of oestrogen receptor‐containing cells. These include regions implicated in the regulation of reproductive neuroendocrine function, and reproductive behaviour. Oestrogen and progesterone synergize to inhibit GnRH secretion and the present results suggest that these functions may involve cells of the VMN and ARC, with oestrogen acting to upregulate PR.

Induction of galanin mRNA in GnRH neurons by estradiol and its facilitation by progesterone

On the day of proestrus in the rat, rising plasma levels of estradiol (E) act in concert with progesterone (P) to trigger a preovulatory release of gonadotropins. Cellular levels of galanin mRNA in GnRH neurons are increased in association with the proestrous surge of gonadotropin secretion; however, the relative contribution made by E and P to the induction of galanin mRNA expression in GnRH neurons is unknown. We investigated the role of E and P in the induction of galanin gene expression in GnRH neurons by examining the effects of different combinations of E (estradiol benzoate; 50 μg and P (5 mg)) on the LH surge and the concomitant induction of galanin mRNA in GnRH neurons. We sacrificed ovariectomized adult rats after 1 of 4 treatments: Group 1: vehicle control (n=6); Group 2: P alone (n=7) Group 3: E alone (n=7); Group 4: combined E/P (n=6); the animals were killed at 18.00 h at the time of the LH surge. The brains from these animals were processed by double‐label in situ hybridization to allow measurement of galanin mRNA levels in GnRH neurons. GnRH neurons were identified with a digoxigenin‐labeled cRNA probe for GnRH mRNA, and galanin mRNA was detected and measured simultaneously with an 35S‐labeled cRNA probe coupled with computerized grain counting. Estimation of cellular levels of GnRH mRNA was accomplished with single‐label in situ hybridization, an 35S‐labeled GnRH cRNA probe and computerized grain counting. We observed a 3‐fold induction of galanin mRNA in the GnRH neurons of animals treated with E alone compared with those treated with the vehicle alone (vehicle: 13±2 vs E: 42±4 grains/cell (g/c); P<0.01); LH levels in the E‐treated animals were elevated, albeit moderately, with respect to the vehicle controls. Compared with vehicle‐treated animals, those treated with the combination of E and P showed a 5‐fold induction of galanin mRNA in GnRH neurons (68±9 g/c), which was significantly (P<0.01) greater than that observed in the animals treated with E alone; in addition, the magnitude of the LH surge was much greater (P<0.05) in the E/P‐treated group compared with the E alone group. In contrast, compared to the vehicle controls, animals treated with P alone (15±2 g/c) showed no discernable effect on galanin mRNA levels; moreover, no LH surge occurred in the P alone group. Neither the number of identified GnRH cells nor their content of GnRH mRNA differed significantly among the experimental groups (GnRH mRNA signal: vehicle controls: 153±6 vs E: 159±6 vs E/P: 153±3 vs P: 148±8 g/c). We conclude that while E is the primary ovarian signal inducing galanin mRNA expression in GnRH neurons and the LH surge itself, P plays a facilitatory role in both of these processes.

The luteinizing hormone pulsatile secretion: Diurnal excursions in normally cycling and postmenopausal women

While numerous investigations have determined characteristics of episodic luteinizing hormone (LH) secretion in women, any diurnal LH rhythmicities during eugonadal and hypogonadal states have not been accurately addressed. Accordingly, blood was sampled at 15-min intervals for 24 h in 45 normally cycling women (16 early follicular (EFP), 14 late follicular (LFP), 15 mid-luteal phase (MLP) women) and in eight postmenopausal women (PMW). Pulse attributes (amplitudes, interpulse intervals) determined in the LH secretory profiles were fitted to cosinor functions to assess diurnal variabilities. In both eugonadal women and PMW, significant (p less than 0.05 or less) diurnal excursions were observed in mean LH levels, with maximal acrophase amplitudes occurring in the EFP and MLP. While these 24-h swings peaked at comparable times (11.00-17.00) during the menstrual cycles, a significant (p less than 0.001) shift in acrophase times to early morning hours (05.30) was noted for PMW. Significant (p less than 0.05 or less) 24-h periodicities were also found for the LH pulse amplitudes. LH pulses were of greater magnitudes during night hours in both cycling women and PMW. A slowing of LH pulses (p less than 0.05 or less) was noted during sleep in EFP and, distinctly, in MLP women. These observations demonstrate diurnal variations in LH secretion and its pulsatile attributes in eugonadal women. Differences in time course and magnitude of these diurnal excursions may be explained by variations in the sex steroid environments. In turn, steroids may modulate other neuroendocrine determinants regulating central time-keepers.

A comparative randomized trial on the impact of two low-dose oral contraceptives on ovarian activity, cervical permeability, and endometrial receptivity

In a double-blind randomized study, the suppression of ovarian activity and anti-conceptive effects on the cervix and endometrium were assessed during administration of two low-dose monophasic oral contraceptives (20 micrograms ethinyl estradiol [EE], 500 micrograms norethisterone--Eve 20 [Grünenthal, Aachen, Germany]; 20 micrograms EE, 150 micrograms desogestrel --Lovelle [Organon, Munich, Germany]). One hundred eighteen healthy women (ages: 18-35 years) were studied in 10 investigation centers during medication with either Eve 20 (n = 59) or Lovelle (n = 59). During three treatment cycles, ovarian activity was evaluated by sonographic determination of follicle-like structures (FLS) and by simultaneous assessment of serum endocrine profiles (gonadotropins LH and FSH, ovarian steroids estradiol [E2] and progesterone [P]). While on either treatment, no ovarian activity (as judged by no FLS and/or reduced sex steroid levels) was found in 90.8% (Eve 20) and 97.2% (Lovelle) of all investigated cycles. Follicular activity or cyst formation were detected in 18 of 173 cycles (Eve 20) and in 5 of 175 cycles (Lovelle), respectively. Gonadotropin levels were suppressed (LH < 6 IU/L, FSH < 8 IU/L) in most treatment cycles (Eve 20 76.6% vs. Lovelle: 84.8%). Serum E2 concentrations exceeding 0.1 nmol/L indicated residual follicular activity in 19.3% (Eve 20) versus 12.2% (Lovelle) of all cycles. An estimated by serum P levels over 5 nmol/L, ovulation had presumably occurred in 4.1% (Eve 20) versus 2.9% (Lovelle) of treatment cycles. However, when the sonographical and endocrinological data were combined, no ovulation was documented in any pill cycle. The quality and quantity of the cervical mucus was found to be minimal in the majority of women. Moreover, the endometrial layer was determined to be low by ultrasound during most pill cycles, indicating equally strong suppressive effects on endometrial receptivity by the two contraceptives. These observations suggest that ovarian activity is suppressed in the majority of cycles during use of low-dose contraceptives. This effect may mainly be medicated by pronounced suppression of serum gonadotropin levels. Strong anti-conceptive effects of these formulations on both cervical permeability and endometrial receptivity are additional factors ensuring the contraceptive efficacy of these formulations.

Inhibition of Steroid‐Induced Galanin mRNA Expression in GnRH Neurons by Specific NMDA‐Receptor Blockade

Galanin mRNA levels in GnRH neurons increase in association with a steroid‐induced LH surge in female rats. Both the steroid‐induced LH surge and the concomitant increase of galanin mRNA in GnRH neurons are blocked by non‐specific inhibition of central nervous system activity imposed by pentobarbital and specific central alpha‐adrenergic receptor blockade. Based on these observations, we hypothesized that galanin gene expression in GnRH neurons is induced whenever GnRH neurons become activated to generate an LH surge. If this were the case, then any neurotransmitter receptor blocking agent that inhibits the LH surge by central mechanisms would likewise block the associated increase in galanin mRNA in GnRH neurons. We tested this hypothesis by examining the effects of an N‐methyl‐D‐aspartate (NMDA) receptor antagonist on the steroid‐induced LH surge and on levels of galanin mRNA in GnRH neurons. Three groups of ovariectomized rats were used: Group 1‐treated with estradiol and progesterone (E/P) and sacrificed at the peak of the LH surge; Group 2‐treated the same as Group 1 except that dizocilpine (MK801, an NMDA receptor antagonist) was used to block the LH surge; and Group 3‐treated the same as Group 1 except they received vehicle instead of E/P. Double‐and single‐label in situ hybridization followed by computerized image analysis were used to measure levels of galanin mRNA and GnRH mRNA in GnRH neurons [as grains/cell (g/c)]. E/P treatment induced a 3‐fold increase in LH levels and a 5‐fold increase in the galanin mRNA signal content of GnRH neurons. Treatment with MK801 completely prevented the LH surge in all animals and also blocked the steroid‐induced increase in galanin mRNA in GnRH neurons. As assessed by 2 independent GnRH single‐labeled assays, neither GnRH message content nor the number of identifiable GnRH neurons differed among the experimental groups. We conclude that the increase in galanin mRNA levels in GnRH neurons is tightly coupled to the occurrence of a steroid‐evoked LH surge, and we infer that induction of galanin gene expression in GnRH neurons is induced as a consequence of synaptic activation of GnRH neurons.

GONADOTROPIN SECRETION DURING AGING IN WOMEN : REVIEW ARTICLE

Biological aging during the postmenopause markedly affects the neuroendocrine control of gonadotropin release. The determination of the age-related dynamics on gonadotropin secretion in postmenopausal women have proven to be a valid approach for delineating changes as a function of progressive age. As a result, major functional derangements, primarily at a hypothalamic rather than a pituitary site, have been determined as concomitants of aging in women. Furthermore, aging may impair the negative feedback sensitivity to ovarian sex steroids, and interfere with the central neurotransmitter activity governing gonadotropin secretion. The data reviewed on gonadotropin secretion in postmenopausal women support the view that the age-related processes are related to a hypothalamic rather than to a pituitary hypofunction.

Effects of ovarian surgery on the dopaminergic and opioidergic control of gonadotropin and prolactin secretion in women with polycystic ovarian disease

Ovarian surgery has been demonstrated as an effective means to establish regular menstrual cycles and resumption of ovulation in patients with polycystic ovarian disease (PCO). We questioned whether such reinstitution of menstrual cyclicity may be associated with changes in the opioidergic and dopaminergic activity known to be aberrant in these women. Opioidergic and dopaminergic tone was therefore assessed in patients with PCO before and after ovarian laser vaporization (n = 4) or classical ovarian wedge resection (n = 4). Blood samples for the determination of luteinizing hormone (LH), follicle stimulating hormone (FSH) and prolactin were frequently obtained following opioidergic and/or dopaminergic antagonism affected by naloxone (4 mg i.v.) or metoclopramide (10 mg i.v.). In response to either surgical approach, circulating LH levels decreased (p < 0.01), while FSH concentrations remained unaltered. Further, LH and FSH concentrations did not noticeably change following challenges with naloxone or metoclopramide: this applied to conditions before and after ovarian surgery. Prolactin release in response to metoclopramide was markedly (p < 0.01) higher following ovarian surgery than before. Thus, both ovarian laser surgery and classical wedge resection can effectively restore normal menstrual cyclicity in PCO patients, although they failed to alter opioidergic and dopaminergic activity. Dopaminergic inhibition of prolactin secretion was further enhanced after ovarian surgery. These observations suggest that different modes of ovarian surgery are effective in influencing central gonadal control, but that the central opioidergic and dopaminergic control of gonadotropin and prolactin secretion remains unaffected by ovarian surgery in PCO women, even when menstrual cyclicity is resumed.

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.

The impact of sleep on gonadotropin secretion

Comparable to the period of pubertal transition, sleep also exerts profound effects on episodic gonadotropin secretion in adult women. During the early follicular phase of the menstrual cycle, a sleep-induced slowing of luteinizing hormone (LH) secretion occurs concurrently with a rise in LH pulse amplitude. A selective increase in opioidergic, but not in dopaminergic or serotoninergic activity may account for this decline in LH pulsatility. In addition, sleep-reversal studies have confirmed that the presence of sleep is essential for the expression of this neuroendocrine function. Since pituitary gonadotropin responsiveness to gonadotropin-releasing hormone (GnRH) is virtually unchanged during sleep, the reasons for the enhanced LH pulse amplitude remain unresolved. This sleep-associated increase in opioidergic activity may be restricted to a hypothalamic site, since opiate blockade does not modify the gonadotropin response to GnRH stimulation. In addition, circadian variability is shown in terms of gonadotropin secretion in regularly cycling women; this may again represent sleep-associated effects on gonadotropin release. Although the physiological importance of sleep-associated neuroendocrine phenomena remains basically unexplained, the observed changes in LH secretory profiles during sleep in adult women suggest close functional links between the endocrine secretion and the rest-activity cycle of the brain.