Luteinizing Hormone Response Research Articles

P.230 Serum alpha-fetoprotein (AFP) level predicts treatment outcome in chronic hepatitis C (ANRS 1211)

Background: Acute sun exposure is the main risk factor for the development of melanoma, especially if associated with a large number of benign melanocytic nevi. Although epidemiologic studies have investigated the effects of exogenous triggers, particularly hormones, our understanding of melanoma is still inadequate.Objective: The aim of this study was to report a case of melanoma that developed after hormonal therapy.Case summary: We report a case of a 26-year-old white woman (weight, 48 kg; Fitzpatrick skin phototype IV; no previous pregnancy) who was referred to the Department of Dermatology, Casa Sollievo della Sofferenza Hospital-IRCCS, San Giovanni Rotondo, Italy, with a malignant melanoma on the left thigh. At the age of 18 years (year 2000), the patient presented with amenorrhea, but no therapy was initiated until 2004. At this time, insufficiency of the gonadal, thyroid, and growth hormone (GH) axes was diagnosed without evidence of hypothalamic-pituitary anatomic damage or of congenital or acquired causes. The patient had an inadequate level of GH (base: 0.8 g/mL; peak: 1.0 ng/mL) during an insulin tolerance test, low levels of thyroid hormones, and a blunted response of luteinizing hormone (base: 0.2 mIU/mL; peak: 10 mIU/mL) and follicle-stimulating hormone (base: 2.6 mIU/mL; peak: 18.5 mIU/mL) to a gonadotrophinreleasing hormone stimulation test. Consequently, replacement therapy with ethinyl estradiol (20 μg) plus progestin (75 μg) (once daily for 21 days/month), levothyroxine (25 μg once daily), and recombinant human GH (0.8 mg SC once daily) was initiated. GH replacement therapy was discontinued after 2 years (June 2006), and thyroid and estrogen replacement therapy were discontinued after 4 years (February 2008). The patient reported first noticing the pigmented lesion 8 months after GH withdrawal, during treatment with the estrogen/progestin combination.Conclusion: We report a case of melanoma onset in a patient who had received hormonal substitutive therapy, where the role of GH therapy alone or in combination with other hormones could not be ruled out.

Evaluation of the Buserelin Stimulation Test in Diagnosing Gonadotropin Deficiency in Males with Delayed Puberty

To assess the efficacy of the gonadotropin-releasing hormone (GnRH) agonist buserelin in a stimulated gonadotropin test for the investigation of delayed puberty in males. Prepubertal males (n = 31; age range, 10.3 to 17.2 years) were studied; buserelin (100 microg) was administered subcutaneously, with blood sampling at 0 and 4 hours for serum luteinizing hormone (LH) and follicle-stimulating hormone (FSH). At follow-up (mean, 4.2 years), 8/31 (26%) failed to progress into puberty, constituting hypogonadotropic hypogonadism (HH), but 23/31 (74%) had testicular enlargement (> or =8 mL) consistent with a normal hypothalamic-pituitary-gonadal (HPG) axis. Stimulated serum LH response to buserelin was lower in males with HH (mean +/- standard error under the mean for HH, 1.4 +/- 0.5 U/L, compared with a normal HPG axis of 17.4 +/- 2.0 U/L; P < .0001). Stimulated serum FSH response was nondiscriminatory (HH, 7.7 +/- 2.2 U/L; normal HPG axis, 11.5 +/- 1.6 U/L; P = .27). All males with HH had a stimulated serum LH level <5 U/L, whereas only 1/23 with a normal HPG axis had a stimulated serum LH below this level. Using this value as the criterion for diagnosing HH, the buserelin stimulation test yielded a sensitivity of 100%, specificity of 96%, and positive predictive value of 89%. The buserelin stimulation test is a highly specific and sensitive GnRH agonist test for the investigation of males with delayed puberty.

Effect of suckling on basal and GnRH-induced LH release in post-partum dairy buffaloes

Suckling, a common practice in smallholder dairy-farming systems in the developing world, delays the onset of post-partum ovarian activity in dairy buffalo. The present study was designed to assess the effect of suckling on pituitary function in lactating buffaloes 25–35 days post-partum. Six suckled and nine non-suckled buffaloes were challenged intravenously with a bolus injection of GnRH (20 μg buserelin acetate; Receptal). Heparinized venous blood samples were collected at 15 min intervals for 2 h before and up to 4 h after GnRH for luteinizing hormone (LH) estimation. Pretreatment basal LH concentrations were similar in the suckled (0.6 ± 0.2 ng/ml) and the non-suckled (0.5 ± 0.1 ng/ml) buffaloes. All but one suckled buffaloes released a LH surge, starting 15–60 min post-GnRH treatment, which lasted for 180–225 min. While one suckled buffalo did not respond to GnRH, the LH response in the remaining suckled buffaloes was significantly less than in the non-suckled buffaloes in terms of peak LH concentrations (14.3 ± 2.7 ng/ml versus 26.2 ± 4.3 ng/ml) and area under the LH curve (1575.6 ± 197.4 mm 2 versus 2108.9 ± 323.9 mm 2). The LH response was least in suckled buffaloes challenged with GnRH while in the luteal phase of an oestrus cycle and with plasma progesterone concentration >1 ng/ml. In conclusion, suckling suppressed pituitary responsiveness to exogenous GnRH challenge in post-partum buffaloes.

Altered responses of prolactin, luteinizing hormone and follicle stimulating hormone secretion to thyrotrophin releasing hormone/gonadotrophin releasing hormone stimulation in cyclical mastalgia.

A generalized abnormality of hypothalamopituitary function was found in 17 patients with cyclical pronounced mastalgia compared with 11 controls by using a combined thyrotrophin releasing hormone and gonadotrophin releasing hormone test. The release of prolactin, luteinizing hormone and follicle stimulating hormone was significantly greater in cyclical mastalgia patients than in controls. Basal thyrotrophin, T3 and T4 levels were within the normal range in both groups indicating normal thyroid status in benign breast disease. The single measurement of oestrogen and progesterone in the luteal phase was not abnormal. These data demonstrate an alteration in lactotroph and gonadotroph function in patients with cyclical mastalgia. It is unknown at present whether this represents an appropriate cellular response to altered central or peripheral signals. There is no evidence to suggest, however, that the anterior pituitary cell types are abnormal per se.

The Histrelin Implant: A Novel Treatment for Central Precocious Puberty

Standard treatment of central precocious puberty (CPP) consists of intramuscular or subcutaneous administration of a gonadotropin-releasing hormone (GnRH) agonist (GnRHa) at 3- to 4-week intervals. Although generally effective in suppressing clinical and laboratory parameters of puberty, GnRHa injections are painful, and the need for monthly clinic visits may contribute to poor compliance. Recently, a subcutaneous implant was developed that releases the GnRHa histrelin at an average rate of 65 microg/day. The aims of this study were to determine if a histrelin implant would suppress gonadotropin and estradiol (E2) in girls with CPP for 1 year and to compare the suppression to standard treatment. We studied 11 girls with CPP to determine if the histrelin implant can maintain long-term gonadotropin suppression. Mean age at diagnosis was 6 years (range: 2-9 years). GnRH (100 microg intravenously) stimulation tests (GnRH-STs) showed peak luteinizing hormone and follicle-stimulating hormone responses of 23 +/- 28 (mean +/- SD) and 20 +/- 25 mIU/mL, respectively. All subjects were initially treated with depot intramuscular GnRHa triptorelin embonate. Implants were inserted subcutaneously under local anesthesia, and depot GnRHa treatment was discontinued. Six girls were followed for 15 months after insertion (group A). For the remaining 5 girls, the implant was removed after 9 months, and a new implant was inserted at the same incision site (group B). GnRH-STs were performed before depot GnRHa treatment, immediately before implant insertion, at the 6- and 9-month visits for each patient and the 12- and 15-month visit for those girls followed for 15 months. In all girls, breast development regressed, growth velocity decreased, and bone-age advancement was slowed. Basal gonadotropins and their responses to GnRH-STs and E2 levels were suppressed. Peak luteinizing hormone and follicle-stimulating hormone responses to GnRH-STs at preinsertion versus 9 months were 1.30 +/- 1.34 vs 0.25 +/- 0.08 and 1.68 +/- 1.08 vs 1.13 +/- 0.55 mIU/mL, respectively. Basal and stimulated gonadotropin levels and E2 level remained suppressed in all 6 patients followed for 15 months after implant insertion. Patients and parents reported less pain and discomfort and less interference with school activity and work with the implant compared with standard monthly injections. The histrelin implant consistently suppresses clinical and laboratory parameters of puberty for 1 year and is a promising new technique for treating CPP without the pain and inconvenience of monthly injections.

Outcome after depot gonadotrophin-releasing hormone agonist treatment for central precocious puberty: effects on body mass index and final height

In their interesting paper, Arrigo et al. (1) investigated longitudinally body mass index (BMI) evolution and prevalence of obesity in girls with idiopathic central precocious puberty (CPP) who were treated with luteinizing hormone-releasing hormone (LHRH) analogs (LHRHa) for at least 2 years. They demonstrated that suppression of the pituitary –gonadal axis function was accompanied by a significant decrease in being overweight. They observed that girls with CPP are frequently obese at diagnosis, suggesting that the pretreatment increase in BMI is due to pubertal hormonal changes and secondary changes in body fat, rather than being a result of CPP (1). We have retrospectively reviewed 29 female patients with idiopathic CPP. The main criteria for diagnosis of idiopathic CPP were (1) onset of breast development and/or menses before 8 years of age, (2) pubertal luteinizing hormone (LH) response to exogenous LHRH (LH peak .10 IU/l), (3) no evidence of hypothalamo –pituitary lesions at magnetic resonance imaging and (4) no additional conditions that might affect BMI. Predicted height was calculated using a computerized Byley–Pinneau method (2). We assessed height SDS, BMI and BMI SDS (3) before, 1 year after the beginning of therapy, at the end of therapy and 2.5 years after the end of therapy. A group of 45 healthy girls with normal onset of puberty was matched for age or for pubertal stage. Statistical analysis was performed with x test and paired sample t-test (P was considered significant if ,0.01). Auxological findings (height SDS, BMI and BMI SDS) and statistical analysis are shown in Table 1. The mean period of treatment was 2.1 years (range 1.9 – 3.1 years). The mean age of menarche in 19 out of 29 girls was 12.1 years (range 10.4 –13.7 years). Eighteen patients complained of side-effects: 16 girls had headache (11 out of 16 isolated headache, two out of 16 with spotting, one out of 16 with joint pain, one out of 16 with increased appetite and one out of 16 with abdominal pain), one girl had isolated spotting and one girl had isolated increased appetite. The final height of the treated girls was in the normal range for parental target height. The reproductive axis appeared to have returned to normal in our patients, with normal menses in 19 out of 30 girls who had already had menarche at the time of our study. In contrast to the study by Arrigo et al. (1) showing a reduction in baseline BMI under LHRHa therapy in girls with CPP, we found an increasing trend in BMI after the first year of therapy, and this did not change after therapy was stopped. With regard to BMI SDS, few changes were observed during the first year of therapy, while an increasing trend was observed at the end of therapy and a complete recovery after 2.5 years of the end of therapy. Nevertheless, in both girls with CPP and the control group, the mean BMI increased; in fact the value in the patients was as much as in the control group during therapy and at the end of therapy. Mean BMI SDS, different in the two groups, was significantly higher in the patients at the end of therapy than in controls, suggesting that the difference was due to the treatment. The data available in the literature on the effects of LHRHa treatment on BMI are few and controversial. Excessive weight gain can occur by various mechanisms: menopausal-like phenomena, or the influence of LHRHa on hypothalamic and/or leptin-mediated control of body weight (4). Some authors have highlighted the fact that obesity is frequent among children with CPP, but does not appear to be related to the longterm pituitary–gonadal suppression induced by LHRHa therapy (5–7). On the other hand, Feuillan et al. (8) showed the association of both CPP and LHRHa with obesity in patients who had increased BMI at initial presentation and during therapy; this condition persisted after discontinuation of therapy and progresses to frank obesity (8).

Lamprey GnRH‐III Stimulates FSH Secretion in Barrows

Although studies have indicated that follicle-stimulating hormone (FSH) and luteinizing hormone (LH) release can be dissociated in the pig, the underlying mechanisms are still to be answered. Since it was demonstrated that lamprey gonadotropin-releasing hormone (l-GnRH-III) has preferential FSH-releasing potency in several mammalian species, we have investigated the gonadotropin-releasing activity of l-GnRH-III in barrows. Each of nine barrows (body weight: 85-90 kg; age: 207 days) received 2 ml saline (S-barrow), followed by 150 microg l-GnRH-III (1.6-1.7 microg/kg body weight) dissolved in 2 ml saline intramuscularly 7 days later. Three pre-treatment and 13 post-treatment blood samples were taken at intervals of 30 min to 8 h to assess basal and treatment-associated concentrations of FSH and LH, respectively, by radioimmunoassay. Animals were defined as having responded to treatment if, 2 h post-treatment, plasma FSH and/or LH levels were >3 SD of the respective basal concentrations. There was no treatment-associated FSH response after saline treatment, but a clear FSH response in all l-GnRH-III-injected barrows. On average, the maximum FSH level (205% of the basal concentration) was observed at 1 h post-treatment. Mean FSH values were elevated until 10 h post-treatment. There was no LH response either to saline or to l-GnRH-III. In conclusion, this study demonstrates a selective FSH-releasing activity of 150 microg l-GnRH-III in barrows. Further studies are needed to investigate whether this effect is ubiquitous in the pig and what the physiological relevance is.

Glucagon‐like peptide‐1 reduces the pulsatile component of testosterone secretion in healthy males

Glucagon-like-peptide-1 (7-36) amide (GLP-1), a potent regulator of glucose homeostasis, has been implicated in the control of hypothalamic-pituitary function. In vivo it is a relevant neuroendocrine modulator of gonadotropin-releasing hormone release, suggesting its possible role as a metabolic signal to the reproductive system. The present study was undertaken to establish its effect on luteinizing hormone (LH) and testosterone secretion in nine healthy male volunteers. Each subject underwent an oral glucose tolerance test to establish LH, testosterone, and GLP-1 responses to glucose. Euglycaemic clamp experiments (6 h) were performed on two occasions with saline or with a constant infusion of GLP-1 (0.4 pmol kg(-1) min (-1)). Blood samples were drawn at 10-min intervals to measure the pulsatile pattern of LH and testosterone secretion. Ingestion of oral glucose resulted in a reduction in plasma testosterone levels at 30 min compared with baseline (P < 0.004) despite unaltered LH levels (P = 0.5). Constant GLP-1 infusion resulted in no change in LH (P = 0.83), testosterone (P = 0.96), follicle stimulating hormone (FSH) (P = 0.86) and leptin levels (P = 0.3). Pulse analysis revealed no significant difference in the number (P = 0.1) or median absolute amplitude (P = 0.3) of the LH pulses. However, there was a significant decrease in the number (3.0 +/- 0.6 vs. 1.3 +/- 0.4; P < 0.05) and a tendency for increased duration of testosterone pulses (97.4 +/- 16.7 vs. 170 +/- 27.1 min; P = 0.06). Oral glucose ingestion and intravenous GLP-1 infusion reduce the pulsatile component of testosterone secretion by a mechanism independent of LH release.

Sex Differences in the Neuroendocrine Response to Short‐Term Fasting in Rhesus Macaques

When energy intake is restricted in mammals, there are neuroendocrine adjustments in the secretion of reproductive and metabolic hormones to reallocate energy for vital functions. In the present study, we investigated whether there were differences in the luteinising hormone (LH), growth hormone (GH) and cortisol responses to a 48-h fast in adult gonad-intact male and female rhesus macaques. In both male and female macaques, blood glucose levels were significantly lower in fasted than in control studies, and levels were higher in males than in females. Male rhesus monkeys had significantly lower (P < 0.01) mean serum LH levels after a 48-h fast than under fed conditions and this was attributable primarily to a decrease in the amount of LH released during each secretory episode. In fasted females, serum LH levels were significantly greater (P < 0.05) than during the fed conditions but no differences were found in pulse amplitude or in the number of pulses. Almost twice as many GH pulses were observed in both males and females during fasting but there was no difference in either mean serum GH levels or pulse amplitude between control and fasted studies. A typical diurnal profile in cortisol levels was observed in both sexes and both experimental conditions. Under control conditions, male macaques released less cortisol than females, and although fasting increased mean cortisol levels in both males and females, only the males shown a significant rise over levels observed in control studies. The changes in plasma LH and cortisol levels in fasted rhesus macaques are similar to those observed in humans and suggest that gonadotrophin and corticotrophin secretion are more resistant to short-term energy deprivation in female than in male primates.

The long-term effect of recombinant methionyl human leptin therapy on hyperandrogenism and menstrual function in female and pituitary function in male and female hypoleptinemic lipodystrophic patients

Lipodystrophy patients are hypoleptinemic and insulin resistant. Women have enlarged polycystic ovaries, hyperandrogenism, and amenorrhea. We have determined the role of correction of hypoleptinemia on these metabolic and neuroendocrine parameters. Ten females and 4 males with generalized lipodystrophy were treated with recombinant methionyl human leptin (r-metHuLeptin) in physiologic doses in an open-labeled study for a period of 12 and 8 months, respectively. In the female group, serum free testosterone decreased from 39.6 ± 11 to 18.9 ± 4.5 ng/dL ( P < 0.01) and serum sex hormone binding globulin increased from 14 ± 2.5 to 25 ± 4.8 nmol/L ( P < 0.02). Luteinizing hormone (LH) responses to LH releasing hormone were more robust after therapy and significantly changed in the youngest group of 3 female patients ( P < 0.01). Ovarian ultrasound showed a polycystic ovarian disease pattern in all patients and did not change after therapy. Eight of the 10 patients had amenorrhea prior to therapy and all 8 developed normal menses after therapy. In the male group, serum testosterone tended to increase from 433 ± 110 to 725 ± 184 ng/dL ( P = 0.1) and sex hormone binding globulin also increased from 18.25 ± 2.6 to 27 ± 1.7 nmol/L ( P < 0.04) following r-metHuLeptin therapy. Serum LH response to LH releasing hormone did not show significant changes. Five additional hypoleptinemic male subjects with minimal metabolic abnormalities underwent normal pubertal development without receiving r-metHuLeptin therapy. In both genders, insulin-like growth factor increased significantly and there were no differences in growth hormone, thyroid, or adrenal hormone levels following r-metHuLeptin therapy. Glycemic parameters significantly improved after r-metHuLeptin therapy in both groups. Hypoglycemic medications were discontinued in 7 of 12 patients and dramatically reduced in 5 patients. r-metHuLeptin therapy plays an important role in insulin sensitivity. In females, it plays an additional role in normalizing menstrual function. This is likely to occur both from increasing insulin sensitivity and from restoring LH pulsatility. The persistent hypoleptinemic state in these subjects did not inhibit pubertal development.

Serum ferritin level as a predictor of impaired growth and puberty in thalassemia major patients

Previous studies suggested that in patients with thalassemia major, initiating deferoxamine (DFO) therapy before puberty can prevent iron-induced failure of growth and puberty. However, early initiation of chelation has also been associated with DFO toxicity. The aim of this retrospective study was to determine the prevalence rates of endocrine complications and DFO bone toxicity in our thalassemia major patients and to correlate them with the degree of iron chelation. Thirty-nine patients with thalassemia major were followed for a median of 16.3 yr (range 2-28). Individual mean serum ferritin level during the study period was calculated using repeated annual measurements. Bone DFO toxicity was assessed by wrist and spine radiographs; endocrine dysfunction by anthropometric measurements and pubertal stage; and hypogonadotropic hypogonadism by lack of luteinizing hormone response to gonadotropin-releasing hormone. Chelation therapy was initiated at median age 4.9 yr. Mean serum ferritin level during the study period was 2698 +/- 1444 ng/mL. Hypogonadism was noted in 59% of the patients who reached pubertal age, and short stature was found in 36% of patients who reached final height. Mean ferritin level of 2500 ng/mL during puberty was the cut-off for hypogonadism, and ferritin level of 3000 ng/mL during prepuberty was the cut-off for final short stature. None of the patients who attained final height had signs of DFO bone toxicity. High serum ferritin levels during puberty are a risk factor for hypogonadism, and high serum ferritin levels during the first decade of life predict final short stature. It remains to be determined whether improving chelation by earlier initiation of DFO or by the combined use of DFO and deferiprone will lead to better growth and sexual development without DFO toxicity.

Inhibin‐producing ovarian granulosa cell tumor as a cause of secondary amenorrhea: Case report and review of the literature

We report the case of 31-year-old patient with an inhibin B-secreting granulosa cell tumor of the left ovary who presented with secondary amenorrhea. Preoperative serum hormonal levels were as follows: follicle-stimulating hormone (FSH) 0.3 mIU/mL, luteinizing hormone (LH) 9.81 mIU/mL, estradiol 142.0 pg/mL and inhibin B 2429 pg/mL. Gonadotropin-releasing hormone (GnRH) test revealed no FSH response and a normal LH response. After removal of the tumor, the levels of FSH and inhibin B returned to within the normal range, and regular menses resumed 27 days postoperatively. In premenopausal women, secondary amenorrhea may be the initial manifestation of granulosa cell tumor. A low FSH level coupled with normal levels of E2 and LH, the inhibition of the FSH response to GnRH and an elevated inhibin level suggest the presence of an inhibin-secreting ovarian tumor and also rule out the possibility of isolated FSH deficiency.

Testosterone and luteinizing hormone responses to naloxone help predict sexual performance in rams1

The first objective of this study was to determine whether LH and testosterone respond differently to a naloxone injection in relation to varying sexual performance in rams. If differences occurred, the second objective was to determine whether differences would predict variation in sexual performance. From a group of 1.5- to 3-yr-old rams, 20 sexually active and 39 sexually inactive rams were selected based on previously observed sexual behavior with estrual ewes. Each ram was exposed to three estrual ewes for 18 30-min sexual performance tests, and those found to be inactive were given two 30-min sexual partner preference tests. The final distribution was 28 sexually active, 22 inactive, and nine male-oriented rams. Rams were treated with 1.5 mg of naloxone/kg BW in December of Year 1 and again with either 0.75 or 1.5 mg of naloxone/kg BW in November of Year 2. Plasma concentrations of LH and testosterone were evaluated with mixed model analyses for repeated measures separately for each year to coincide with logistic procedures for modeling the probability that rams were sexually active. For Year 1, a sexual activity x age x time interaction for LH after naloxone was observed (P < 0.03). For testosterone, there was a sexual activity x time interaction (P < 0.03), with a similar, early increase for sexually active female-and male-oriented rams compared with a delayed, minimal increase for inactive rams. For Year 2, when all rams were over 2.5 yr of age, a sexual activity x time interaction for both LH and testosterone (P < 0.02) seemed more related to an earlier increase of both hormones for sexually active rams than the increase observed for inactive rams. In addition, sexually active rams had a greater increase in testosterone than inactive rams. No significant difference was observed between 0.75 and 1.50 mg of naloxone/kg BW. Testosterone and LH were used as explanatory variables and sexual activity was used as the response variable in logistic procedures. In Year 1, greatest prediction accuracy was 73.5% using testosterone at 60 min after naloxone injection. In Year 2, the greatest prediction accuracy was 85% using LH at 15 min multiplied by testosterone at 60 min after naloxone. Test repeatability for both years on the same rams was 76%. In conclusion, pattern and magnitude of naloxone-induced changes in endocrine function may facilitate identification of sexually active and inactive rams during the breeding season. Prediction accuracy of the naloxone-based test was 69 to 85%.

Pituitary hormone responses to luteal regression after administration of prostaglandin F2alpha-analogue.

As an experiment to elucidate the canine luteal function maintenance system, a PGF2alpha-analogue, fenprostalene (PGF-F), was administered 24 and 54 days after ovulation to induce luteal regression, and the responses of luteinizing hormone (LH) and prolactin (PRL), which are considered to support the canine corpus luteum, were investigated. The plasma progesterone (P(4)) level was rapidly decreased, by which the plasma PRL level was increased, but no change was observed in the plasma LH level. The decrease in the plasma P(4) level after PGF-F administration may have induced positive feedback to the superior system, and stimulated secretion of the pituitary hormones. These findings suggested that the canine corpus luteum is maintained by PRL, not by LH.

Disturbances in gonadal axis in women with anorexia nervosa

There is no uniform opinion about the nature of the hormonal disturbances in patients with anorexia nervosa and their relationship with clinical presentation. The objective of the study was to characterize the disturbances in the gonadal axis and their relationship with the body weight, duration of the disease and amenorrhoea in patients with anorexia nervosa. Prospective study. We have assessed serum levels of luteinizing hormone (LH), follicle-stimulating hormone (FSH), sex hormones and sex hormone binding globulin (SHBG) in 40 women with anorexia nervosa, aged 19.1 ± 5.1 years with body mass index (BMI) 15.14 ± 1.80 kg/m2 and average degree of weight loss 28.67 ± 8.74%. The duration of the disease was 3–120 months. The basal levels of gonadotropins and their responses to 100 μg gonadotropin-releasing hormone (GnRH) i.v. and 100 mg clomiphene citrate per oral for 5 days were studied. Fifteen healthy age-matched women with normal weight and regular menstrual cycles served as controls. Statistically significant lower basal gonadotropin levels were found in the patients than the controls (LH: 3.22 ± 0.54 vs. 7.19 ± 0.6, P <0.001; FSH: 3.58 ± 0.4 vs. 4.96 ± 0.34, P <0.05). The responses of LH to GnRH were diminished, but those of FSH were exaggerated. The area under the curve (AUC) of FSH in the anorexics (11.13 ± 7.42 IU/L/min) was higher than in the controls (6.98 ± 1.94 IU/L/min, P <0.05). AUC of LH was lower, but not significant. However, after clomiphene citrate, LH increased 5.4 times in comparison with the basal levels, whereas FSH increased only 1.7 times. The basal concentration of SHBG in the patients (165.27 ± 63.5 nmol/L) was significantly lower than in the controls (96.21 ± 38.04 nmol/L, P <0.01). We observed a significant correlation between the basal levels of LH and the body weight (r = 0.291, P <0.05), BMI (r = 0.377, P <0.02) and percentage of the weight loss (r = -0.288, P <0.05). Similarly, a significant correlation between the basal levels of SHBG and the body weight (r = -0.761, P <0.01), BMI (r = -0.513, P <0.05) and percentage of the weight loss (r = 0.654, P <0.05) were noted. The alterations of FSH were related to the duration of the disease (r = 0.448, P <0.001) and the amenorrhoea (r = 0.450, P <0.001). The results of this study demonstrate dissociation in the gonadotrophic secretion after stimulation with some hypothalamic stimuli in women with anorexia nervosa. It shows that the disturbances in the patients gonadal axis correlate directly with the changes in the body weight and with the duration of the disease.

Female pheromones stimulate release of luteinizing hormone and testosterone without altering GnRH mRNA in adult male Syrian hamsters ( Mesocricetus auratus)

In many species chemosensory stimuli function as important signals that influence reproductive status. Neurons synthesizing the peptide gonadotropin-releasing hormone (GnRH) are critical mediators of reproductive function via their regulation of the hypothalamic–pituitary–gonadal (HPG) axis, and they are thought to be responsive to chemosensory information. In the present study, we sought to elucidate the effects of female chemosensory stimuli on the HPG axis in sexually naive adult male Syrian hamsters. In Experiment 1, serial blood samples were collected from catheterized male hamsters following exposure to female pheromones in order to characterize the luteinizing hormone (LH) response to this chemosensory stimulus. In Experiment 2, brains and terminal blood samples were collected from animals 0, 60, and 120 min following pheromone exposure. GnRH mRNA was measured in brain tissue sections using in situ hybridization, and plasma concentrations of LH and testosterone were measured using radioimmunoassay. Data from Experiment 1 indicated that female pheromones elicited a rapid rise in plasma LH that peaked at 15 min and returned to baseline 45 min after exposure. In Experiment 2, testosterone was elevated in terminal blood samples obtained 60 min, but not 120 min, after exposure to pheromones. LH levels were unaffected at both of these time points. The chemosensory-induced increases in LH and testosterone release were not accompanied by subsequent changes in GnRH mRNA over the time course studied. These data suggest that while activation of the male HPG axis by female pheromones involves release of GnRH, it does not involve increases in GnRH mRNA 1–2 h after pheromonal stimulation as a mechanism for replenishment of released peptide.

The interrelationships between thyroid dysfunction and hypogonadism in men and boys.

Thyroid hormone deficiency affects all tissues of the body, including multiple endocrine changes that alter growth hormone, corticotrophin, glucocorticoids, and gonadal function. Primary hypothyroidism is associated with hypogonadotropic hypogonadism, which is reversible with thyroid hormone replacement therapy. In male children follicle-stimulating hormone (FSH) is elevated and associated with testicular enlargement without virilization. Men with primary hypothyroidism have subnormal responses of luteinizing hormone (LH) to gonadotropin-releasing hormone (GnRH) administration and normal response to human chorionic gonadotropin (hCG). Free testosterone concentrations are reduced in men with primary hypothyroidism and thyroid hormone replacement normalizes free testosterone concentrations. In men with primary hypothyroidism, prolactin is not consistently elevated (except in men and children with longstanding severe primary hypothyroidism), but prolactin declines following thyroid hormone replacement therapy. Thyroid hormone is known to affect sex hormone-binding hormonal globulin (SHBG) concentrations. Men with hyperthyroidism have elevated concentrations of testosterone and SHBG. Thyroid hormone therapy in normal men may also duplicate this elevation. In addition estradiol elevations are observed in men with hyperthyroidism, and gynecomastia is common in them as well. In contrast to patients with primary hypothyroidism, men with hyperthyroidism exhibit hyperresponsiveness of LH to GnRH administration and subnormal responses to hCG. Radioactive iodine therapy (RAI) of men treated for thyroid cancer produces a dose-dependent impairment of spermatogenesis and elevation of FSH up to approximately 2 years. Permanent testicular germ cell damage may occur in men treated with high doses of RAI. RAI commonly increases serum concentrations of FSH and LH while reducing inhibin B levels without affecting serum concentrations of testosterone. Thus, radioiodine therapy transiently impairs both germinal and Leydig cell function that usually recover by 18 months posttherapy.

Ghrelin effects on gonadotropin secretion in male and female rats

Ghrelin is a 28-amino acid peptide primarily involved in the control of food intake and growth hormone secretion. The present experiments were carried out to analyze the potential involvement of ghrelin in the control of gonadotropin secretion. Prepubertal intact and gonadectomized female and male rats, cyclic rats in diestrus, lactating rats and aged female rats were i.c.v. injected with ghrelin (3 nmol/rat) and blood samples were obtained by decapitation 15 min later. In addition, we analyzed the effects of ghrelin on in vitro basal and luteinizing hormone-releasing hormone (LHRH)-stimulated gonadotropin secretion. Our present results indicate that ghrelin inhibited luteinizing hormone (LH) secretion in vivo in prepubertal males as well as gonadectomized males and females, whereas follicle-stimulating hormone (FSH) remained unaffected. In vitro, ghrelin stimulated the secretion of both gonadotropins, and differentially modulated the response to LHRH; the LH response was inhibited, while the FSH response was enhanced. Overall, our current data open up the possibility that ghrelin may be involved in the control of LH secretion, and in the dissociation of both gonadotropins that takes place in many physiological, pathological and experimental situations.

Mechanisms for altered reproductive function in female rats following neonatal administration of raloxifene.

Raloxifene is a non-steroidal selective estrogen receptor modulator (SERM) that mimics estrogenic activity on bone density and blood lipid concentration without uterotropic actions. Previous data from our laboratory indicated that, as is the case for estrogen, neonatal administration of raloxifene disturbed normal differentiation of the hypothalamic circuitries governing the gonadotropic axis. In contrast, raloxifene did not act in the same way as estrogen does on the neuronal systems controlling sexual receptivity in the female rat. At present, however, the mechanisms for these organizing effects of raloxifene are not completely elucidated. To analyze this phenomenon, female rats were injected daily with raloxifene (50, 100, 250 or 500 microg/rat per day) between days 1 and 5 of age. On day 23, hypothalamic gonadotropin-releasing hormone (LHRH) mRNA expression was assessed, and pituitary and plasma luteinizing hormone (LH) and follicle-stimulating hormone (FSH) levels were measured in basal and LHRH-stimulated conditions. In addition, LH and FSH responses to ovariectomy were evaluated in raloxifene-treated females. Finally, we monitored the ability of neonatal administration of a potent LHRH agonist ([d-Ala(6),d-Gly(10)]-LHRH ethylamide; 0.01 microg/kg per 12 h on days 1-5) to counteract the effects of raloxifene. Our analyses demonstrated that prepubertal rats (23-day-old females) treated neonatally with raloxifene showed decreased hypothalamic LHRH mRNA expression levels, reduced pituitary content of LH and FSH, reduced basal and LHRH-stimulated LH secretion in vivo and in vitro, and decreased response to ovariectomy. In addition, adult females treated neonatally with raloxifene showed anovulation and reduced serum LH levels; these effects were not prevented by the simultaneous administration of a LHRH agonist. In conclusion, our data demonstrate that neonatal administration of raloxifene can disrupt the programming of hypothalamic-pituitary-ovarian axis function. Reduced LH secretion, under basal and LHRH-stimulated conditions and after ovariectomy, is probably related to decreased LHRH expression, reduced pituitary LH content and/or decreased pituitary responsiveness to hypothalamic LHRH.

Postpartum gonadotropin secretion in Holstein-Friesian dairy cows differing genetically in liveweight

AIM: To determine whether there are differences in postpartum gonadotrophic activity between strains of Holstein-Friesian dairy cows genetically selected on mature liveweight that might explain differences between the strains in fertility, and the interval between calving and the resumption of ovarian follicular activity. METHODS: Mixed-age Holstein-Friesian cows fed generous allowances of ryegrass/white clover pasture, and genetically selected for heavy (H) or light (L) mature liveweight, were given 10 µg buserelin on Days 21, 28, 35 and 42 (Experiment 1a;n=8/ group), or Days 7, 14, 21 and 28 (Experiment 1b; n=8/group) postpartum. The same dose of buserelin was also given to first-calved heifers from each strain (Experiment 1c; n=6/group) on Days 7, 14, 21, and 28 postpartum. Luteinising hormone (LH) concentrations were measured in serial blood samples that were taken for up to 240 min after administration of buserelin. In Experiment 2, serial blood samples were taken at 15-min intervals from H and L cows (n=7/group) over 8 h on Days 14, 21, 28 and 35 postpartum, to examine the endogenous secretion patterns of LH and follicle stimulating hormone (FSH). The time-course of the restoration of positive feedback between oestradiol and LH was examined by giving 1 mg oestradiol ben-zoate (ODB) 48 h after administration of 500 µg cloprostenol to mixed-age cows from each strain on Days 7 and 21 (n=8/group), or 14 and 28 (n=8/group) after calving (Experiment 3). Relationships between nutrition and the restoration of positive feedback were studied by giving 0.75 mg ODB/500 kg liveweight on Day 17 or 18 after calving to pure-bred Holstein (OSH) and New Zealand Friesian (NZF) cows that were fed either pasture (n= 12 OSH, 12 NZF) or a total mixed ration (TMR; n= 13 OSH, 12 NZF) (Experiment 4). Plasma LH and FSH concentrations were measured in samples collected for 42 h (Experiment 3) or 48 h (Experiment 4) after treatment with ODB. Milk progesterone concentrations were measured 3x weekly to define the reproductive status of animals in each experiment. Conception rates were recorded for animals in all of the experiments. RESULTS: First-service conception rates were lower (p<0.05) in H than L cows (46% vs 59%). In Experiments 1b and 1c, LH response to buserelin increased between Days 7 and 28 postpar-tum (both p<0.001), but did not differ between strains (p=0.77 and p=0.19, respectively). In Experiment 1a, LH responses to buserelin did not change between Days 21 and 42 postpar- tum, but overall mean peak concentrations were significantly (p<0.001) greater in L than H cows. In Experiment 2, anoestrous H cows had higher mean (p=0.004) and episodic (p=0.001) concentrations of LH than did L cows, but in cows that had active corpora lutea there were no such differences. There were no differences in FSH concentrations between strains. LH secretion in response to exogenous oestradiol (Experiment 3) increased between Days 7 and 28 postpartum (p<0.001), but there were no differences between strains. Responses were also similar in OSH and NZF cows on Day 17 or 18 postpartum, although there was a significant effect of ration upon the proportion of cows that exhibited an LH surge (20/24 cows on grass vs 12/25 on a TMR; p=0.005). CONCLUSION: These results confirm that H cows have poorer first-service conception rates than L cows, but do not support an hypothesis that there are major differences between these strains of Holstein-Friesian dairy cows in the rate of restoration in the hypothalamo-pituitary axis. However, in anoestrous cows, differences between strains in the endogenous release of LH may be related to an earlier onset of oestrous cycles in H animals.