Diminished function of the somatotropic axis in older reproductive-aged women.

Circulating GH and insulin-like growth factor-I (IGF-I) levels in adults generally fall with age. Studies in aging women have rarely controlled for menstrual cycle stage or status or body mass index. We hypothesized that GH and IGF-I levels in reproductive-aged women fall with age despite the stimulatory effects of endogenous estradiol (E2). Eight older reproductive-aged women (aged 42-46 yr) with regular menses, of normal weight, and in good health were compared to a group of eight young control subjects (aged 19-34 yr). Daytime frequent blood sampling was performed in the early follicular phase of the menstrual cycle to characterize pulsatile GH and LH concentrations. Pooled samples were also analyzed for IGF-I, E2, progesterone, and FSH levels. Older reproductive-aged women had lower 12-h integrated daytime GH concentrations (mean +/- SE, 171 +/- 35 vs. 427 +/- 130 micrograms min/L; P = 0.036) than younger controls and a strong trend for lower IGF-I levels (22.7 +/- 2.1 vs. 31.3 +/- 3.5 nmol/L; P = 0.055) than younger controls despite having higher circulating E2 on the day of sampling (368 +/- 51 vs. 167 +/- 20 pmol/L; P = 0.002). We conclude that older reproductive-aged women have lower daytime GH concentrations than younger controls despite having higher E2 levels on the day of sampling and overall normal gonadal hormone parameters.

Testosterone, a follicular regulator: key to anovulation.

To study the interrelationships of steroids within the follicle, combined 6-h infusions of [3H]dehydroepiandrosterone sulfate and [14C] testosterone ([14C]T) were performed in four normal women treated with menotropins who were undergoing medically indicated surgery. The concentrations of tracer and/or nonisotopic dehydroepiandrosterone sulfate, androst-5-ene-3 beta,17 beta-diol sulfate, androst-5-ene-3 beta,17 beta-diol, dehydroepiandrosterone, androstenedione, T, dihydrotestosterone, estrone (E1), and estradiol (E2) were determined in arterial and venous blood and follicular fluid. The log-transformed product/precursor ratio of [3H]dihydrotestosterone/[3H]T in follicular fluid was negatively correlated with the log-transformed follicular concentrations of E1 (P = 0.01) and E2 (P = 0.02), suggesting a reciprocal relationship between 5 alpha-reductase and follicular E1 and E2. E2 and T were positively correlated in follicular fluid (r = 0.84; P = 0.0003), suggesting a stimulatory action of follicular T on aromatase. These findings along with extensive published data suggest that follicular T functions as a follicular regulator, enhancing follicular aromatase activity when adequate amounts of FSH are available. These conclusions have important implications with regard to mechanisms for selecting the dominant follicle and producing atresia in the remaining cohort of follicles, and they describe a final common path in the pathophysiology of anovulation.

Plasma dehydroepiandrosterone sulfate serves as a prehormone for 48% of follicular fluid testosterone during treatment with menotropins.

Evidence has suggested that dehydroepiandrosterone sulfate (DS) is a prehormone for ovarian steroidogenesis. To study this hypothesis, combined 6-h infusions of [3H]dehydroepiandrosterone sulfate and [14C]testosterone ([14C]T) were performed in four normal women treated with menotropins who were undergoing medically indicated surgery, and the data were compared to those from nine normal women. The concentrations of tracer and nonisotopic DS, androst-5-ene-3 beta,17 beta-diol sulfate (delta 5diolS), androst-5-ene-3 beta,17 beta-diol (delta 5diol), dehydroepiandrosterone (D), androstenedione (delta 4A), and T were determined in arterial and venous blood and in follicular fluid. From these data, the concentrations and fractions of steroids in the follicular fluid that were derived from DS were calculated from the specific activity of intravascular DS and the concentrations of follicular fluid tracer steroids and their specific activities. The fractions of T (0.48), delta 5diol (0.31), delta 5diolS (0.42), and D (0.25) in follicular fluid arising from circulating DS were similar and were not significantly different from that of follicular DS arising from circulating DS (0.32). However, the fraction of follicular fluid delta 4A (0.041) was significantly less (P < 0.01), and the fractions of intrafollicular estrone and estradiol arising from DS were both less than 0.04. The mean MCR of DS in the women treated with menotropins of 22.0 +/- 3.5 L/day (mean +/- SE) was significantly higher than the normal control value. These findings elucidate an important mechanism of adrenal/ovarian interaction at the level of steroidogenesis; circulating DS serves as a prehormone for the production of intrafollicular delta 5diolS, delta 5 diol, D, and T.

Metabolic clearance rate of dehydroepiandrosterone sulfate, its metabolism to testosterone, and its intrafollicular metabolism to dehydroepiandrosterone, androstenedione, testosterone, and dihydrotestosterone in vivo.

At the time of surgery, women were infused with [3H]dehydroepiandrosterone sulfate ([3H]DS)/[14C]testosterone ([14C]T) for 6 h; blood samples were obtained from an artery the ovarian veins, and a peripheral vein; and fluid was obtained from ovarian follicles. Both blood and follicular fluid samples were analyzed for radioactivity as DS, dehydroepiandrosterone (D), androstenedione (delta 4A). T, and dihydrotestosterone (DHT), and the blood was also analyzed for the concentration of nonisotopic DS by RIA. In other subjects the concentrations of D and DS were measured in paired samples of blood and follicular fluid. From these data, values of 13.6 +/- 0.69 L/day four (mean +/- SE; n = 4) for MCRDS, 607 +/- 90 L/day (n = 3) for MCRT, and 0.0190 +/- 0.0089 (n = 3) for [p]DS-T (fraction of plasma DS metabolized to plasma T) were obtained. The ratio of the concentration of the tracer-labeled steroid in the follicular fluid to the concentration in the arterial plasma sample was elevated significantly above 1 for three 3H-labeled and three [14C-labeled metabolites: [3H]D (21-fold; P less than 0.001), [3H]T (81-fold; P less than 0.001), [3H]DHT (19-fold; P less than 0.001), [14C]T (4-fold; P less than 0.025), [14C]DHT (21-fold; P less than 0.01), and [14C]delta 4A (50-fold; P less than 0.001). The estimated concentrations of steroids in follicular fluid derived from DS based on specific activity calculations were as follows: [geometric mean (95% confidence limits; n)]: DS, 5600 (4800-6500 nmol/L; 12); D, 370 (88-1500 nmol/L; 10); delta 4 A, 120 (67-220 nmol/L; 12); T, 130 (39-450 nmol/L; 10); and DHT, 64 (35-120 nmol/L; 8). Comparison of these data to known follicular fluid steroid concentrations shows that DS from the intravascular pool can be used as an ovarian prehormone.

Bilateral compartment syndrome after a long gynecologic operation in the lithotomy position.

Compartment syndrome occurred after a tubal anastomosis in a prolonged lithotomy position. This syndrome carries the risk of permanent neuromuscular and kidney damage. The pathophysiologic features of the syndrome are reviewed. Specific guidelines for the prevention and management of this syndrome in patients undergoing gynecologic procedures are presented.

Puberty without gonadotropins. A unique mechanism of sexual development.

Recent evidence suggests that a group of children exists in whom premature sexual maturation occurs in the absence of pubertal levels of gonadotropins; that is, they have gonadotropin-independent precocious puberty. We compared six boys and one girl with this disorder with four boys and five girls with central precocious puberty, in which there is a pubertal pattern of gonadotropin release. The two groups were similar in age of onset, degree of sexual development, growth velocity, and rate of skeletal maturation. A family history of precocity was noted in four of the boys with gonadotropin-independent precocity, and the girl had McCune-Albright syndrome. Children with central precocious puberty demonstrated a pulsatile release of gonadotropins, pubertal responses to luteinizing hormone-releasing hormone, and complete suppression of gonadarche after exposure to an analogue of luteinizing hormone-releasing hormone (LHRHa). In contrast, children with gonadotropin-independent precocity demonstrated an absence of gonadotropin pulsations, variable responses to luteinizing hormone-releasing hormone, lack of suppression of puberty in response to LHRHa, and cyclic steroidogenesis. Tissue from testicular biopsies performed in five of six boys with gonadotropin-independent precocity showed a range from incipient pubertal development of the tubules with proliferation of Leydig cells to the appearance of normal adult testes. We conclude that gonadotropin-independent precocious puberty is a distinct syndrome, of unknown cause, that may be familial and may have been responsible for many previously reported cases of precocious puberty.

LH responses to LHRH in perifused pituitary cell culture: sex differences in the rat.

The present experiments were designed to study male and female luteinizing hormone (LH) secretory patterns following pulsatile or continuous LH-releasing hormone (LHRH) administration using a perifused dispersed rat anterior pituitary cell culture system. In male cells, consistent LH responses were elicited by hourly LHRH pulses (30 pmol), whereas in the female cells (proestrus or diestrus I), a statistically significant (P less than or equal to 0.01) decrease in the LH secretion occurred with successive LHRH pulses. Proestrous cells secreted significantly (P less than or equal to 0.01) more LH than diestrous cells during the first 24 h but not after 48 h in culture. When exposed to a 6-h continuous infusion of LHRH (10 nM), male cells released LH in a single phase and female cells secreted LH in a biphasic pattern. These data suggest that significant sex differences exist in the rat LH secretory pattern elicited by LHRH in vitro.

Long-term treatment of central precocious puberty with a long-acting analogue of luteinizing hormone-releasing hormone. Effects on somatic growth and skeletal maturation.

The gonadotropin-releasing hormone-like agonist D-Trp6-Pro9-NEt-LHRH (LHRHa) has been shown to induce a reversible short-term suppression of gonadotropins and gonadal steroids in patients with central precocious puberty. Since accelerated statural growth and bone maturation are clinical features of precocity not well controlled by conventional therapies, we examined the effects of prolonged LHRHa therapy for 18 consecutive months on growth and skeletal maturation in nine girls with neurogenic or idiopathic precocious puberty. Suppression of gonadotropin pulsations and gonadal steroids was maintained in all subjects. Growth velocity fell from a mean rate (+/- S.E.M.) of 9.35 +/- 0.64 cm per year during the 19 months before treatment to 4.58 +/- 0.60 cm per year during treatment (P less than 0.001). Bone age advanced a mean of 9.4 +/- 2.3 months during treatment. These changes resulted in a mean increase of 3.3 cm in predicted height (P less than 0.01). Complete suppression of the pituitary-gonadal axis can be maintained by LHRHa therapy, resulting in slowing of excessively rapid growth and skeletal maturation and in increased predicted adult height in girls with precocious puberty.

The luteinizing hormone-releasing hormone (LHRH)-desensitized rat pituitary: luteinizing hormone responsiveness to LHRH in vitro.

Desensitization of the anterior pituitary has been observed after continuous infusion of LHRH or repetitive administration of LHRH at concentrations or frequencies exceeding physiological limits. We have studied the LH responsiveness of the LHRH-desensitized male rat anterior pituitary in a continuously perifused dispersed cell culture system. Infusion of 10 nM LHRH initially stimulated a 4- to 5-fold increase in LH secretion which became maximal at 6-9 min and which declined gradually to a preinfusion baseline over 6 h. Since the cells did not maintain peak levels of LH secretion in the presence of continuous exposure to LHRH, they were considered to be desensitized. These desensitized cells were studied to determine their LH responsiveness to LHRH. Cells desensitized by a 6-h LHRH infusion responded to four hourly LHRH boluses of 200 pm by releasing four statistically equal LH pulses. The response of desensitized cells to 200 pm LHRH was similar to that of 10 pm LHRH of nondesensitized cells. Furthermore, desensitized anterior pituitary cells responded to LHRH in a linear dose-dependent manner. The dose response of desensitized cells ranged from 75-500 pm, whereas for nondesensitized cells a dose response was observed from 1-75 pm. In addition, anterior pituitary cells desensitized with continuous LHRH infusion can respond to a second LHRH infusion of a greater concentration and become desensitized for a second time. These data suggest that the capacity of the pituitary gland to store and secrete LH while desensitized is similar to that of the nondesensitized anterior pituitary. The major difference between cells desensitized with LHRH and nondesensitized cells is that desensitized cells require a larger dose of LHRH to elicit a given LH response.

Perifused pituitary cultures: a model for LHRH regulation of LH secretion.

In this paper, a dispersed anterior pituitary cell system that is continuously perifused and suitable for the study of luteinizing hormone-releasing hormone (LHRH)-anterior pituitary physiology is described. Adult male Sprague-Dawley rats were decapitated and the anterior pituitaries removed, dispersed using collagenase, mixed with Biogel P2, and packed into 0.9-cm columns using sterile technique. All experiments were conducted using Krebs-Ringer-bicarbonate-glucose buffer, and a stable base line was achieved. A constant dose of LHRH (50 ng) administered several times at 1-h intervals stimulated the same quantal release of LH. LH secretion is linear in response to LHRH over the range of 1-50 nM and to rat hypothalamic extracts over a range of 1/32 to 1/2 hypothalamic equivalents, regardless of whether the extracts are administered in ascending or descending order. These results indicate that perifusion of dispersed pituitary cells provides a useful model for the study of LHRH physiology, combining the advantages of the long-term viability of pituitary cells in culture with the dynamic nature afforded by perifusion.