The plant metabolite 6-methoxybenzoxazolinone interacts with follicle-stimulating hormone to enhance ovarian growth

6-Methoxybenzoxazolinone (6-MBOA) is a novel plant metabolite that enhances reproductive status in vertebrate consumers while it inhibits insect, fungal, and bacterial infestation of the plant. Ovaries of prepubertal rats show a dose response to increasing amounts of 6-MBOA.administered in Silastic capsule implants. Ovaries increased in size in response to capsules with 0.5-3.0 cm exposed surface area of 6-MBOA, whereas larger capsules (6 cm 6-MBOA) had no effect. Removal of the pituitary in both prepubertal and mature rats eliminated the stimulatory influence of 6-MBOA. In hypophysectomized animals treated with diethylstibestrol implants, 6-MBOA did not affect ovarian weight and no animals ovulated. Administration of follicle-stimulating hormone (FSH) increased ovarian weight and stimulated production of ova, and FSH combined with 6-MBOA resulted in larger ovaries that released more ova. 6-MBOA also enhanced ovarian growth in intact prepubertal animals treated with pregnant mare's serum gonadotropin. These results show that 6-MBOA has the ability to interact with FSH to stimulate follicular development and increase ovulation. Non-steroidal plant compounds may have a significant impact on the reproductive patterns of wild animal populations.     

Photoperiod affects reproductive responsiveness to 6-methoxy-2-benzoxazolinone in house mice

House mice (Mus musculus) have traditionally been characterized as nonphotoperiodic because reproductive function is unaffected by day length in the laboratory. In the present study, the reproductive responsiveness of CF1 mice to a naturally occurring plant metabolite was assessed in animals that were maintained in either long (16L:8D) or short (8L:16D) photoperiods from birth until the end of the study. Males and females were implanted i.p. with either an empty Silastic capsule or one containing 6-methoxy-2-benzoxazolinone (6-MBOA) at either 21 or 60 days of age for 3 days. Other 31-day-old mice were implanted with capsules for 8 wk. Three-day exposure to 6-MBOA stimulated uterine growth in short-day, adult females, but did not affect adult females housed in long photoperiods. Short-term treatment with 6-MBOA did not significantly affect reproductive parameters in either long- or short-day peripubertal house mice, or in adult males regardless of photoperiod, nor did exposure to 6-MBOA for 8 wk influence reproduction in males in either photoperiodic condition. However, short-day female mice had significantly reduced ovarian and uterine masses after 8 wk chronic 6-MBOA treatment as compared to long-day animals or mice unexposed to 6-MBOA. Short-day females exposed to 6-MBOA for 8 wk developed a denser pelage compared to long-day mice treated with this compound. Photoperiod-mediated differential responsiveness to 6-MBOA indicates that female house mice can discriminate long from short days, and these results suggest that the physiological mechanisms for photoperiodic responsiveness remain extant in this species previously characterized as nonphotperiodic.     

Effects of 6-MBOA on reproductive function in ponies, mice, rats and mink

The effect on reproduction of the plant derivative 6-methoxybenzoxazolinone (6-MBOA), which stimulates reproductive function in voles, was tested in pony mares, laboratory mice and rats, and mink. There was not a significant effect of intravenous injections of 6-MBOA on the ovarian follicles during the transition between the anovulatory and ovulatory seasons in mares. No significant effect of intraperitoneal injections of 6-MBOA on the weight of uterus or ovaries was found in eight-week-old mice, failing to confirm the results of an earlier report. In immature white rats, 6-MBOA treatment resulted in an increase in uterine weight (P<0.05) at the lowest dose tested (0.03 mug/rat; mean for controls, 34 +/-2 mg; treated, 47 +/-5 mg). However, no significant effect was found on the weights of the ovaries and other glands or in coded scores for ovarian stimulation and uterine fluid distention. Adding 1.5 mg 6-MBOA to the daily feed ration of mink beginning two weeks before the mating season did not affect the mean number of kits born. Nulliparous female mink had smaller (P<0.001) litter size than multiparous females. In addition, of the mink that whelped, there were more (P<0.01) nulliparous females (25 118 ) than multiparous females (9 144 ) that lost one or more kits within 48 hours. These results, however, were not altered by 6-MBOA treatment.     

Effect of gonadotropin-releasing hormone,stage of sexual maturation and 6-methoxybenzoxazolinone on plasma gonadotropins,ovarian development and uterine weight in prepuberal gilts

Two experiments were conducted with prepuberal gilts at 60, 120 and 160 days of age to a) determine the effect of 6-methoxybenzoxazolinone 6-MBOA) on reproductive plasma hormone concentrations and organ development, and b) determine how plasma follicle-stimulating hormone (FSH) and luteinizing hormone (LH) concentrations before and after injection of gonadotropin-releasing hormone (GnRH) or 6-MBOA varied in relation to ovarian development. In Exp. 1, 12 gilts were used in a 4×4 Latin square design. Four gilts/age group were injected once with: 1) vehicle, 2.5% propylene glycol in 50% ethanol, 2) 2 μg of GnRH/kg body weight (BW), 3) 0.2 mg of 6-MBOA/kg BW, and 4) 2 mg of 6-MBOA/kg BW on four successive days in random order. Blood was collected via indwelling vena cava catheters. Injection of GnRH into gilts increased plasma FSH and LH at each age compared with vehicle (P<0.05). Hormone profiles for FSH and LH differed among age groups (P<0.01), but area under curves did not differ significantly among age groups. Injection of 6-MBOA did not significantly affect plasma FSH and LH. Plasma FSH and LH before the GnRH injection or on days when GnRH was not injected were greater at 60 than at 120 and 160 days (FSH, 128 vs 54 and 42 ng/ml; LH, 0.38 vs 0.16 and 0.13 ng/ml for 60, 120 and 160 days, respectively (P<0.05). In Exp. 2, vehicle, 0.2 or 2 mg of 6-MBOA/kg BW were injected once daily for 7 days in 19 gilts. Injections of 6-MBOA had no detectable effects on gonadotropin secretion, ovarian development or uterine weight. Between 60 and 120 days of age, vesicular follicles developed, ovarian weight increased 20-fold, and uterine weight increased 10-fold (P<0.05); basal concentrations of plasma FSH and LH decreased three- and twofold, respectively.     

Hormonal consequences of subcutaneous 6-methoxy-2-benzoxazolinone pellets or injections in prepubertal male and female rats

Prepubertal 27-day-old female rats maintained in a 14L:10D cycle (lights on 06:00 h) were injected s.c. at 13:00 h with saline or 2, 20 or 200 micrograms 6-methoxy-2-benzoxazolinone (6-MBOA) and killed 25-27 h later. No significant differences in body, pituitary or ovarian weight were noted. Differences in uterine weight (mg/100 g body weight) and in circulating free thyroxine index fit the pattern of a reduction after the lower doses with reversal of this effect after the highest dose. A dose-related rise in plasma prolactin concentration was accompanied by a significant increase in pituitary prolactin at the lowest (2 micrograms) dose. When 27-day-old prepubertal male and female rats maintained in a 14L:10D cycle were implanted with a beeswax pellet or a wax pellet that contained 100 micrograms or 1 mg 6-MBOA and killed 3 days later between 14:00 and 16:00 h, body and absolute ventral prostate weights (but not weights of other accessory organs, testes or relative ventral prostate weights) in males were lower. Pituitary (but not plasma) prolactin concentrations were higher after the lower dose compared to the controls; pituitary and plasma values of LH and FSH were unchanged. In females, reproductive variables were unchanged except for a reduction of pituitary prolactin after the 1 mg dose. Triiodothyronine and its free index were elevated after the higher dose in males and the lower dose in females. The free thyroxine index appeared raised after the larger dose only in males.(ABSTRACT TRUNCATED AT 250 WORDS)     

Reproductive response of Tatera leucogaster (Rodentia) to supplemental food and 6-methoxybenzoxazolinone in Zimbabwe

The effects of 6-methoxybenzoxazolinone (6-MBOA) and supplemental food on the reproductive activity of Tatera leucogaster were examined using a field experiment. The experiment was carried out during the dry season when no pregnancies were observed. Animals provided with 6-MBOA-treated millet seeds for 10 days were not significantly different from animals provided with sham-treated seeds. Supplemental food appeared to have no effect on female reproductive activity, but increased the body mass of both sexes and also the mass of the testes and seminal vesicles. These results provide no evidence for an effect of 6-MBOA on reproductive activity of this equatorial rodent, but supplemental food may promote the maturation and recrudescence of reproductive organs in males.     

Activity of the hypothalamo-pituitary ovarian axis in hypothyroid rats with or without triiodothyronine replacement

The hypothalamic pituitary ovarian axis in adult female rats with 131-I induced hypothyroidism was studied before and after triiodothyronine (T3) replacement. Forty days after 131-I, hypothyroid (H) rats showed irregular cycles with predominantly diestrous vaginal smears, atrophied and underweight ovaries, and decreased serum T3, T4, LH and estradiol (E2). T3 replacement restored normal cycles and ovary weight and increased serum E2 levels above control values, while LH levels remained below the limit of detection of the RIA. The GnRH stimulation test performed on the day that the rats exhibited diestrous vaginal smears elicited a greater increase in FSH than in LH in H rats and a greater increase in LH than in FSH in both H-T3 treated and control rats. The data suggest that the lack of thyroid hormones in adult female rats seems to produce a reversion of sexual hormones to a prepubertal pattern, while T3 treatment restored normal estrous cycles and ovarian function.     

Effect of 6-methoxybenzoxazolinone on sex ratio and breeding performance in Microtus montanus

The plant derivative, 6-mathoxybenzoxazolinone (6-MBOA), which has been demonstrated to initiate reproduction in field populations of the montane meadow vole (Microtus montanus), was administered via feeding or Silastic capsule implants to mated pairs of laboratory bred M. montanus. The animals remained paired for 120 days, and the number, size, and sex ratios of the resulting litters were recorded. Both the size and frequency of litters were significantly greater in 6-MBOA-treated pairs than in controls. By using implants, it was possible to treat one or both sexes in a mated pair. The positive effects of this compound on litter size and number of litters occurred when the females received implants, which indicates that the male has no influence on these parameters. The most unusual result of these experiments was that 6-MBOA has a significant effect on the sex ratio of the litters. Animals receiving 6-MBOA produced significantly more females than did control pairs. This result occurred regardless of the method of administration, and in the case of the implant studies, regardless of which sex received the active implants. These findings are discussed in relation to the ecology and life history strategy of Microtus montanus.     

Selective oocyte degeneration and impaired fertility in rats treated with the aliphatic monoterpene, Citral.

Mature female rats treated with Citral (3-7-dimethyl-2,6-octadienal) either topically for 60 or 100 days or by 6 i.p. injections (at 4-5 day day intervals) showed a marked decrease in the number of normal follicles per section, because oocytes tended to degenerate although the follicular cells remained normal. The reproductive performance after Citral treatment was impaired: there was a reduction in implantation number and litter size and an increased post-implantation fetal wastage. None of the young survived after 100 days of topical Citral treatment. It is suggested that Citral directly affects the oocytes.     

Early treatment of young female rats with progesterone delays the aging-associated reproductive decline: a counteraction by estradiol

We have recently reported that successive treatments of young virgin rats with progesterone (P) implants produce elevated circulating P and consistently low estradiol (E2) concentrations, and subsequently delay the aging-associated reproductive decline. Inasmuch as E2 has been implicated in causing the loss of regular estrous cyclicity in aging rats, the present study examined if the concomitant presence of moderately increased circulating E2 levels could counteract the effects of P implants on reproductive aging. Starting at 3 1/2 mo and continuing to 8 mo of age, regularly cyclic, virgin rats received either s.c. Silastic implants of P (P-implanted), blank Silastic implants (virgin controls), or P + E2 implants (P + E2-implanted) for 3 wk, followed by implant removal for 1 wk. Each of these implant treatments was repeated in the same female rats 5 times. Blood samples were obtained on different days of the estrous cycle from the control group and on Day 11 of successive treatments with P or P + E2 implants for measurements of serum P and E2 values. At 8 1/2 and 10 mo of age, estrous cyclicity of these same virgin rats was again monitored, and 10-mo-old regularly cyclic females from each treatment group were mated with young fertile males to complete term pregnancies. While virgin controls showed cyclic increases in E2 and P secretion during the estrous cycle, P-implanted virgins exhibited consistently low serum E2 and moderately increased P levels during 5 successive treatments. The latter indicates a potent inhibition of ovarian E2 secretion by P implants.(ABSTRACT TRUNCATED AT 250 WORDS)     

The plant metabolite, 6-methoxybenzoxazolinone, stimulates an increase in secretion of follicle-stimulating hormone and size of reproductive organs in Microtus pinetorum

The plant metabolite, 6-methoxybenzoxazolinone (6-MBOA), occurring in leaf tissue of rapidly growing monocots, cues reproduction in some mammals. In the pine vole, Microtus pinetorum, peripubertal females respond to this nonestrogenic compound with a 40% increase in serum levels of follicle-stimulating hormone (FSH). In addition, 6-MBOA significantly increases the weight of the ovary and uterus in both peripubertal and mature voles. This study is the first to offer evidence that 6-MBOA interacts with the pituitary to stimulate reproduction in voles.     

Effects of age and pregnancy on cytochrome P450 induction by octamethyltetracyclosiloxane in female Sprague-Dawley rats

Dimethylcyclosiloxanes (DMCS) are components of silicone gel containing implants and are known inducers of human drug metabolizing enzymes. The effects of the major DMCS, octamethyltetracyclosiloxane (D4) on cytochrome P450 (CYP) induction were examined in young adult, mature, and pregnant female Sprague-Dawley rats. Also, the ability of D4 administered to pregnant dams to affect CYP expression in fetal liver was examined. Female young, mature, and pregnant Sprague-Dawley rats were administered 0, 5, 20, and 100 mg/kg D4 daily by gavage for 8 days. Liver microsomal CYP (CYP2B, CYP3A, CYP1A) concentrations were evaluated by Western blots using specific antisera, and CYP activities were assayed using CYP selective assays. D4 treatment resulted in a significant induction of CYP2B and CYP3A isoforms. CYP induction was dose and age dependent. A comparison of the inducibility of CYP3A protein by D4 in rats from different age groups showed that the degree of increase was the highest in the pregnant rats at doses of 20 mg/kg D4 or higher. The mature rats had a lesser degree of responsiveness than did the young rats at the dose of 100 mg/ kg D4. Significant increases in CYP2B immunoreactive protein concentrations were observed in young and mature rats given D4 at doses >5 mg/kg and in pregnant rats at doses >20 mg/kg. Maximal CYP2B induction detected with blotting was more than 90-fold in mature rats; however, no significant changes were detected in CYP1A expression. There was a 20% increase of liver to body weight ratio in the mature rats treated with 100 mg/kg D4. D4 has different inductive properties in female rats of different ages and reproductive status. Also, D4 administered to the pregnant dam is capable of inducing CYP expression in fetal liver as well as decreasing fetal body weight.     

Effect of p-chlorophenylalanine on LH, FSH, prolactin and ovulation in the rat

The effect of p-chlorophenylalanine (PCPA: 300 mg/kg) on the rate of ovulation and plasma LH, FSH and prolactin secretion has been studied in rats at preovulatory periods (18th hour of diestrus) and post-ovulatory periods (9th hour of metaestrus). In both experimental groups, results showed that administration of PCPA caused an increase in both prolactin concentration and number of mature ovarian follicles (p less than 0.001). No changes were observed in FSH levels. LH concentration, however, decreased (p less than 0.001) and ovulation became totally inhibited. Rats treated at the 9th hour of metaestrus exhibited a marked luteinization as well as an increased number of corpus luteum in the ovaric tissue (p less than 0.001), whereas those treated at the 18th hour of diestrus underwent no luteinization and merely showed a greater number of mature ovarian follicles (p less than 0.001). PCPA, therefore, seems not to have a double effect on ovulation, LH, FSH, and prolactin secretion regardless of the pre or post-ovulatory periods. Changes observed in the ovaric tissue might be due to an increase in plasma prolactin concentration which appears earlier in the preovulatory than in the post-ovulatory treated animals. This difference may explain the double effect that has been attributed to the ovaric cycle and reproductive behavior.     

Deceleration of age-associated changes in the preovulatory but not secondary follicle-stimulating hormone surge by progesterone

Recently, it has been reported that mating can delay the age-associated decline in reproductive function of female rats. Since circulating progesterone (P) levels are elevated for a 2- to 3-wk interval during pregnancy, the following study was conducted to determine whether intermittent elevation in P levels can alter the rate of reproductive aging in female rats. Beginning at 2 mo of age, 4-day-cycling, virgin rats were divided into two groups. In one group, 3 Silastic capsules containing crystalline P were inserted s.c. into each rat while rats in another group each received 1 empty capsule. After 2 wk, the capsules were removed for 2 wk. Thereafter, implantation and removal of capsules was repeated 5 additional times. Rats receiving P capsules became acyclic 3-4 days after exposure to P and resumed cyclicity 4-7 days after removal of P-capsules. One month after the last series of capsules was removed (rats approximately 8-mo-old), rats exhibiting consecutive 4-day cycles were inserted with indwelling atrial cannulae and bled at 4-h intervals from 1400 h on proestrus (Pr) to 1000 h on estrus (E). At 1600 h E, rats were killed and trunk blood was collected. For comparison, a group of 3-mo-old (young) rats was bled on Pr and E. In 8-mo-old rats that received empty capsules, 27% exhibited 4-day cycles compared to 66% of the young rats. However, in contrast to rats that received empty capsules, 63.1% of P-treated rats exhibited 4-day cycles. Surges of preovulatory luteinizing hormone (LH) and follicle-stimulating hormone (FSH) surges were attenuated in 8-mo-old rats given empty capsules compared to young rats.(ABSTRACT TRUNCATED AT 250 WORDS)     

Endocrine and ultrasound evaluation of a non‐cycling African elephant: Identification of an ovarian follicular cyst

The reproductive rate of captive African elephants is low because of logistical difficulties associated with transporting animals for breeding, the danger of maintaining bulls and medical or physiological problems. There also is growing evidence that a significant number of mature female elephants are not experiencing normal estrous cycles. The case described in this report involves the diagnosis and attempted treatment of an ovarian follicular cyst in an African elephant at the Pittsburgh Zoo. On the basis of serum progesterone analysis, the female exhibited regular ovarian cycles from July 1993 through March 1994, but from November 1994 to the present has not shown any evidence of reproductive cyclicity. In April 1996, a large follicular structure was identified on the right ovary using transrectal ultrasound. In an attempt to luteinize the cyst, 500 μg gonadotropin‐releasing hormone (GnRH) was administered intravenously in October 1996, which stimulated a modest increase in serum luteinizing hormone (LH) (approximately twofold over baseline), but no resumption of ovarian activity. The elephant was treated again 5 months later with a higher dose of GnRH (5 mg, i.v.) with the same results. An ultrasound evaluation in July 1997 indicated the structure was still present. In October 1997, the female was given human chorionic gonadotropin (hCG; 10,000 IU, i.m.), which induced estrus and breeding, but no ovulation or luteinization of the cyst, and she remains acyclic. These results suggest that conventional methods developed in other species for treating ovarian follicular cysts may not necessarily be effective in the elephant. It is also important that reproductive age females be monitored via continuous progesterone analysis and occasional reproductive tract ultrasound evaluations to understand better the etiology of ovarian dysfunction so that effective treatments can be developed to induce consistent ovarian activity. Zoo Biol 18:223–232, 1999. © 1999 Wiley‐Liss, Inc.     

Anti-fertility effects of embelin in female Sprague-Dawley rats may be due to suppression of ovarian function

Effects of embelin on oestrous cycle, plasma levels of progesterone and oestradiol, and in vitro production of oestradiol and progesterone by mixed ovarian cells was studied. Forty adult (4 months old) regularly cycling female Sprague-Dawley rats were divided into four groups of 10 rats each. Groups I and II (controls) were given 1 ml/kg body weight of physiological saline or corn oil (vehicle). Groups III and IV received 10 mg/kg and 20 mg/kg body weight embelin in corn oil, respectively. Emberlin disrupted the oestrous cycles in Groups III and IV animals, and there was a significant depression in plasma oestradiol (p <0.05) and progesterone (p <0.02) at both 10 and 20 mg/kg body weights, respectively. Isolated mixed ovarian cells from embelin treated rats produced significantly less progesterone and estradiol than controls in vitro. It is concluded that embelin probably interferes with reproductive functions in female rats by suppressing ovarian production of sex steroid hormones.     

Effect of gold on stimulation of reproductive function in immature female albino rats

Significant increase in ovarian and uterine weight and stimulation of ovarian delta5-3beta-hydroxysteroid dehydrogenase (delta5-3beta-HSD) activity and elevation of serum estradiol level were observed following gold chloride (0.2 mg/kg body weight/day), s.c. administration in immature female albino rats. Moreover, normal cyclic changes of estrus were found in vaginal smears of these rats whereas the rats of other groups showed diestrus phase throughout the period of experiment. Histological study of ovary also showed Graafian follicle with ovum in rats treated with 0.2 mg/kg/day of gold proving stimulation of reproductive function, which was not found in the ovarian histological study of other groups including controls. Thus, the results suggest a significant stimulatory effect of gold chloride on female reproductive activity in immature rats. Further, since the above-mentioned changes were evident at a specific dose of gold chloride, the data may have some clinical implications on stimulation and enhancement of fertility in immature female rats.     

Use of a neuroleptic in assisted reproduction of the critically endangered Mohor gazelle (Gazella dama mhorr)

Stress is a limiting factor in assisted reproduction in wild animals maintained in captivity and measures to reduce it should improve reproductive success. The effect of the long-acting neuroleptic (LAN) perphenazine enanthate was assessed on ovarian stimulation for the recovery of immature oocytes from Mohor gazelle (Gazella dama mhorr) and their subsequent in vitro maturation, fertilization and embryo culture. The viability of embryos after transfer was also examined. Perphenazine enanthate decreased activity levels and facilitated handling of treated animals when compared to controls. LAN-treated animals showed a more regular pattern of respiratory and heart rates and body temperature than controls; no major differences were found in hematological and biochemical parameters between groups. Perphenazine-treated females had lower plasma cortisol levels during the days of intense handling. No significant differences were found in the number of punctured follicles and recovered oocytes between groups. The percentage of mature oocytes per female was significantly higher in the LAN-group. Fertilization and cleavage rates were not significantly different between groups. Embryos developed in culture but none reached the blastocyst stage, and those transferred to the oviduct of synchronized recipients did not develop to term. In conclusion, treatment of females with perphenazine enanthate during ovarian stimulation did not have negative effects on maturation, fertilization and embryo development in vitro. Moreover, an increase in oocyte maturation rate per female was observed. Thus, the use of LANs could be useful to alleviate the effects of handling-stress during assisted reproductive procedures in wild ungulates.     

Opiate antagonist counteracts reproductive inhibition by porcine ACTH extract.

The effects of naloxone, an opiate receptor antagonist, on the maturation of female mice chronically pretreated with ACTH from weaning, were examined. Naloxone treatment, begun at 40 days of age, blocked ACTH-induced delay of puberty. Naloxone also reversed decreases in weights of the reproductive organs produced by ACTH. Naloxone treatment also resulted in estrous cycling and increased the number of ACTH-treated mice with ovarian corpora lutea. These changes are reflected in increased LH levels in ACTH-naloxone treated vs. ACTH-saline treated animals. Naloxone alone may increase reproductive function. Effects of ACTH on spleen and thymus weights, presumably via the adrenals, were partially reversed by naloxone. ACTH may have a different mechanism in adrenal function as compared to reproductive function.     

Hypothalamic-adenohypophyseal origin of reproductive failure in mice following chronic infection with Toxoplasma gondii

Mice chronically infected with Toxoplasma gondii exhibited reproductive failure characterized by a constant diestrous vaginal cytology and ovarian and uterine atrophy. Chronically infected mice were treated with 20 ng of D-Leu6-des-Gly-NH2-Pro-ethylamide (D-Leu6), a structural analog of luteinizing hormone-releasing hormone (LHRH), every 4 hr over a 12-hr period daily, for 3 days. Infected animals treated with D-Leu6 had greater pituitary weight (P less than 0.01), ovarian weight (P less than 0.01), and uterine weight (P less than 0.025), than did infected control mice treated with saline. In addition, a change in vaginal cytology to estrus, metestrus, and proestrus of the D-Leu6-treated animals was observed, although a contiguity of normal estrous cycles and reproductive function was not determined. Comparable basal levels of serum luteinizing hormone (LH) were seen in infected mice and uninfected normal mice. However, the infected animals demonstrated a decreased pituitary responsiveness to D-Leu6 when monitored at 60 (P less than 0.025) and 120 min (P less than 0.010) following intraperitoneal administration of a bolus of 200 ng of the analog. Thus, the observed reproductive failure involves the readily releasable pool of pituitary LH, since basal LH is similar in both groups, and appears to be due to a dysfunction of the hypothalamic-adenohypophyseal axis.