Simultaneous Radioimmunoassay of Plasma Testosterone and Dihydrotestosterone

Fully automated method for quantitative determination of steroids in serum: An approach to evaluate steroidogenesis

Steroidogenesis is a set of metabolic reactions where the enzymes play a key role to control the physiological levels of steroids. A deficiency in steroidogenesis induces an accumulation and/or insufficiency of steroids in human blood and can lead to different pathologies. This issue added to the low levels of steroids (pg mL^-1 to ng mL^-1) in this biofluid make of their determination an analytical challenge. In this research, we present a high-throughtput and fully automated method based on solid-phase extraction on-line coupled to liquid chromatography with tandem mass spectrometry detection (SPE-LC-MS/MS) to quantify estrogens (estrone and estradiol), androgens (testosterone, androstenedione, dihydrotestosterone and dehydroepiandrosterone), progestogens (progesterone, pregnenolone, 17-hydroxyprogesterone and 17-hydroxypregnenolone), glucocorticoids (21-hydroxyprogesterone, 11-deoxycortisol, cortisone, corticosterone and cortisol) and one mineralocorticoid (aldosterone) in human serum. The performance of the SPE step and the multiple reaction monitoring (MRM) mode allowed reaching a high sensitivity and selectivity levels without any derivatization reaction. The fragmentation mechanisms of the steroids were complementary studied by LC-MS/MS in high-resolution mode to confirm the MRM transitions. The method was characterized with two SPE sorbents with similar physico-chemical properties. Thus, limits of quantification were at pg mL^-1 levels, the variability was below 25% (except for pregnenolone and cortisone), and the accuracy, expressed as bias, was always within ±25%. The proposed method was tested in human serum from ten volunteers, who reported levels for the sixteen target steroids that were satisfactorily in agreement with the physiological ranges reported in the literature.

Effects of a micronutrient supplementation combined with a phosphodiesterase type 5 inhibitor on sperm quantitative and qualitative parameters, percentage of mature spermatozoa and sperm capacity to undergo hyperactivation: A randomised controlled trial

The main objective of this study was to evaluate the effects of a micronutrient supplementation (MS) combined with avanafil on sperm function. Oligoasthenospermic men (n = 217) were treated daily for 90 days with either an MS (45 men, Group A), l-carnitine (44 men, Group B), MS plus avanafil (43 men, Group C) or avanafil (43 men, Group D); another group of 42 men with oligoasthenospermia (Group E) received no treatment. Sperm parameters were evaluated before and after the end of treatment in each Group A, B, C and D respectively. The same sperm parameters were measured in each participant of Group E before and at the 90-day experimental period. Within Groups A, C or D, the total percentage of motile spermatozoa, the hypoosmotic swelling test (HOST) result and the percentage of hyperactivated spermatozoa after incubation under conditions known to induce sperm capacitation were significantly greater after MS or MS plus avanafil treatment, or avanafil treatment than before the respective treatment. We suggest that MS or MS plus avanafil combined administration or avanafil alone improves sperm membrane permeability with an overall result improvement in sperm motility, outcome of HOST and increase in the percentage of hyperactivated spermatozoa.

Ultrasensitive Detection of Testosterone Using Microring Resonator with Molecularly Imprinted Polymers

We report ultrasensitive and highly selective detection of testosterone based on microring resonance sensor using molecularly imprinted polymers (MIP). A silicon-on-insulator (SOI) micoring resonator was modified by MIP films (MIPs) on a surface. The MIPs was synthesized by thermopolymerization using methacrylic acid as functional monomer and ethylene glycol dimethacrylate as crosslinking agent. The concentration of detected testosterone varies from 0.05 ng/mL to 10 ng/mL. The detection limit reaches 48.7 pg/mL. Ultrahigh sensitivity, good specificity and reproducibility have been demonstrated, indicating the great potential of making a cost effective and easy to operate lab-on-Chip and down scaling micro-fluidics devices in biosensing.

Influence of unilateral castration and increased plane of nutrition on sexual development of Holstein bulls. III. Endocrine responses

Pituitary gonadotropic hormones were assayed in 65 Holstein bulls from 7 days to 16 months. Pituitary LH concentration and content at 2, 4, 8 and 16 months increased (P<.01) with age, while FSH content increased with age (P<.01) but was lower in UC bulls at 2, 4 and 8 months and higher at 16 months (A x UC, P<.01) as compared to intact bulls. In five samples of plasma collected at 90-minute intervals, one day each month from 1 to 15 months in 10 of the bulls killed at 16 months, LH concentration and variance changed (P<.01) with age reaching maxima at 4 and 3 months respectively. Plasma testosterone concentration and variance changed (P<.01) with age, reaching maxima at 10 and 9 months respectively. In the other 10 bulls killed at 16 months, assays of plasma collected before and after exposure to a teaser showed that stimulation increased LH by 20 minutes after exposure but LH declined by 60 minutes while testosterone was increased 20 (P<.05) and 60 (P<.01) minutes after exposure.

Effects of phosphodiesterase-5 inhibitors on Leydig cell secretory function in oligoasthenospermic infertile men: a randomized trial

OBJECTIVE

to evaluate the effects of phosphodiesterase-5 inhibitors (PDE5-i) on Leydig cell secretory function (LCSF).

PATIENTS AND METHODS

in all, 75 men with oligoasthenospermia were treated daily for 12 weeks with either vardenafil (23 men, group A), sildenafil (25 men, group B) or l-carnitine (26 men, group C); a further group of 22 men with oligoasthenospermia (group D) received no treatment. Serum levels of insulin-like-3 peptide (INSL3) were evaluated before and after the end of the treatment in each of groups A, B and C, respectively. Serum INSL3 levels were measured in each participant of group D before and after the 12-week experimental period.

RESULTS

within group A and B, the peripheral serum mean INSL3 concentration, sperm concentration, percentage of motile spermatozoa, and percentage of morphologically normal spermatozoa were significantly greater after PDE5-i treatment than before.

CONCLUSION

we suggest that PDE5-i enhances LCSF, as the mean INSL3 concentration was significantly greater after PDE5-i administration than before, within groups A and B. This enhancement in LCSF might contribute to the increase in sperm concentration and sperm motility after administration of PDE5-i.

The effect of repeated intramuscular gonadotrophin-releasing hormone injections on luteinizing hormone, follicle-stimulating hormone, testosterone, oestrogens, dehydroepiandrosterone and dehydroepiandrosterone sulfate in normal men

The endocrine response to three daily intramuscular injections of 500 microgram LH-RH was measured in 9 normal men during a period of 3 days. A marked but declining response in LH was seen in addition to a significant increase in the serum concentration of FSH, testosterone, oestradiol and the urinary excretion of oestrogenic substances. No change could be demonstrated in the DHA, DHAS or cortisol secretion which confirms our previous results of a direct effect of clomiphene on adrenal steroidogenesis.

Clinical characteristics of 18-year-old men with elevated blood pressure

Twenty "hypertensive" 18-year-old men (systolic BP greater than or equal to 146 and/or diastolic BP greater than or equal to 90 mmHg) from the screening examinations of a military draught bureau were compared with 17 normotensive (systolic BP 124-131) and 12 hypotensive (systolic BP 100-106) subjects. The hypertensive subjects were on average taller, showed more often ECG evidence of sympathoadrenomedullary overactivity, tended to excrete more adrenaline in the urine during a standardized psychological stress test, had higher serum levels of sodium and potassium and reported more frequently family prevalence of hypertension than the normotensives and hypotensives. Non-participating subjects without verified hypertension had higher mean relative weight than any of the study groups. Only one hypertensive subject showed dilated pulmonary vessels on chest X-ray and borderline evidence of mild left ventricular hypertrophy. None of the hypertensive subjects showed evidence of decreased glomerular filtration rate or endocrine disorder. The subjects in both comparison groups showed frequently ECG evidence of parasympathetic activity. The hypotensive group had a lower average relative body weight than the other groups.

Sex hormones and the changes in adolescent male lipids: longitudinal studies in a biracial cohort

OBJECTIVE

To determine the role of increasing free testosterone and estradiol in pubertal changes in male lipids.

METHODS

We conducted a 3-year, longitudinal, observation study with biannual visits of 251 black and 285 white boys who were 10 to 15 years of age at enrollment. Sex hormones, lipid parameters, and body composition measures were obtained according to a standard protocol. The body mass index (kg/m(2)) was used to characterize obesity.

RESULTS

White boys had higher triglycerides, lower high-density lipoprotein cholesterol (HDL-C), lower apolipoprotein (apo)AI, and higher apoB than black boys. In boys of both races, increased body mass index was associated with increases in triglycerides, low-density lipoprotein cholesterol, apoB and decreases in HDL-C and apoAII. Within this framework, increased free testosterone was associated with increased apoB and decreased HDL-C and apoAI, whereas increased estradiol was associated with increased HDL-C and decreased triglycerides, low-density lipoprotein cholesterol, and apoB.

CONCLUSION

Changes in sex steroid hormones have significant effects on changes in lipid parameters-increasing free testosterone levels has atherogenic effects and increasing estradiol has antiatherogenic effects.

Inhibition of lordosis behavior in male and female rats by androgens and progesterone

Several studies suggest that when manipulated experimentally in adulthood, the lordosis response to estrogen can be increased dramatically in male rats. Because adult-gonadectomized (Gx) animals were used in these studies, the lack of testicular hormones in adulthood may have been a factor. To examine this possibility, adult-Gx rats were implanted with blank (Bk)-, testosterone (T)-, 5alpha-dihydrotestosterone (DHT)-, or progesterone (P)-filled capsules, alone or in combination. We report a new finding, that a combined treatment of T plus P (T+P) at physiological doses for the male, but not T or P alone, reduced lordosis significantly in males, with and without estrogen priming. T+P did not inhibit lordosis in females, nor did this specific treatment affect open field, aggressive, and male copulatory behaviors. In confirming studies done with much higher doses, DHT reduced lordosis in both sexes. DHT and T+P also reduced lordosis in adrenalectomized/Gx males. Mechanisms responsible for the T+P inhibition of lordosis in males are not known, but they may include an upregulation of androgen receptors by P, and this possibility is discussed.

Relapse of hirsutism following long-term successful treatment with oestrogen-progestogen combination

OBJECTIVE

While several forms of treatment have been reported to be successful in relieving hirsutism over periods of 6-12 months, there is little if any information on the long-term outcome of hirsutism following the withdrawal of successful treatment. The combination of ethinyl oestradiol, 35 micrograms, and cyproterone acetate, 2 mg (EE-CA) for 21 days followed by 7 days without treatment is widely used in a cyclical manner in the treatment of hirsutism. The present study was undertaken to evaluate the outcome of withdrawal of long-term successful treatment of hirsutism with EE-CA. DESIGN, PATIENTS AND MEASUREMENT: In this retrospective study the clinical records of 57 patients with idiopathic hirsutism or polycystic ovary syndrome who had been treated with EE-CA were reviewed. The degree of hirsutism had been assessed by the Ferriman and Gallwey scoring system (FG). The testosterone/sex hormone binding globulin ratio (T/SHBG), was derived prior to and following the introduction of treatment with EE-CA.

RESULTS

Fifty-two of the 57 patients achieved a satisfactory clinical response. In the group of patients who were satisfied with the outcome of treatment, FG decreased from 12.9 +/- 3.6 to 5.5 +/- 2.5 and T/SHBG ratio decreased from 11.3 +/- 9.5 to 1 +/- 0.8 (reference range: 1-5.2). The duration of treatment prior to its withdrawal in this group was 28.2 +/- 13.7 months. The five patients who were not satisfied with the response abandoned treatment after 16 +/- 2.8 months; the pretreatment FG was 16.2 +/- 8.3, while the T/SHBG decreased from 6.1 +/- 3.1 to 1.1 +/- 0.6 in these patients. Subsequent follow-up data, after withdrawal of treatment, were available on 34 of these 52 patients. Twenty-eight of the 34 patients exhibited relapse of hirsutism after 6.15 +/- 2.8 months. Six patients did not relapse during a follow-up period of 18.8 +/- 7. 8 months. The six patients who did not relapse were treated for a significantly longer period than the group who relapsed, 40 +/- 6.9 and 26.1 +/- 8.3 months, respectively, P < 0.01. However, the groups did not differ significantly when examined for pretreatment FG, 11.5 +/- 3.8 and 13.2 +/- 3.6 and pretreatment T/SHBG 8.9 +/- 5 and 13.4 +/- 11.9.

CONCLUSION

These data indicate that ethinyl oestradiol and cyproterone acetate achieved a satisfactory clinical outcome in the treatment of hirsutism in 90% of patients. However, on withdrawal of treatment after a mean duration of over 2 years, relapse occurred in 80% of these patients after a mean of 6 months. If it is assumed that the successfully treated patients lost to follow-up all maintained long-term remission, the relapse rate is still an unsatisfactory 65% at 6 months. These are disappointing results which indicate for the first time that successful outcome requires that treatment be maintained for several years. Patients embarking upon treatment for hirsutism should be advised that maintenance of reduced hair growth requires long-term treatment, probably for at least 3-4 years.

Influence of the male reproductive tract on the reproductive potential of round spermatids abnormally released from the seminiferous epithelium

Round spermatids can be collected from testicular biopsy material or occasionally from semen samples. We evaluated the influence of the passage of round spermatids through the male reproductive tract on their reproductive potential. A model of abnormal release of round spermatids from the seminiferous epithelium was created in mature male rats (group A). Additional sham-treated rats of the same age served as a control group (group B). Round spermatids were collected from the testicles of rats of both groups, the epididymides of rats of group A, and the vaginae of mature female rats mated with rats of group A. Isolated round spermatids were processed for ooplasmic injections. Injected oocytes were cultured. At 96 h post-injection, the blastocyst development rate was significantly higher in the groups of oocytes injected with testicular spermatids than the groups of oocytes injected with spermatids recovered from the vaginae, or the head, body, or tail of the epididymides. It appears that round spermatids recovered from testicular biopsy material have larger reproductive capacity than ejaculated round spermatids, due to mechanical or chemical detrimental influences of storage/passage through the male reproductive tract (outside the testicle) on the capacity of round spermatids to induce optimal early embryonic development.

Effects of hypercholesterolaemia on Leydig and Sertoli cell secretory function and the overall sperm fertilizing capacity in the rabbit

The effects of hypercholesterolaemia on testicular endocrine and exocrine function were evaluated. The influence of hypercholesterolaemia on sperm quality, quantity, and fertilizing potential was also determined. Ten mature rabbits (group A) were fed chow containing 3% cholesterol for 12 weeks. Ten control rabbits (group B) were fed normal chow for the same period. At the end of the experimental period testosterone profiles and sperm parameters were evaluated and the sperm reproductive potential was assessed by in vitro fertilization (IVF) techniques. Peripheral serum testosterone responses to testicular stimulation with human chorionic gonadotrophin, androgen-binding protein activity in testicular cytosols, sperm concentration, sperm motility, length of sperm midpiece, and IVF outcome were all significantly lower in group A than in group B. In contrast, serum cholesterol concentrations were significantly higher in group A. There were no significant differences in either testicular versus intra-abdominal temperature differences or cholesterol concentrations in seminal plasma or testicular tissue between groups A and B. The results suggest that hypercholesterolaemia has a detrimental effect on Leydig and Sertoli cell secretory function, spermatogenesis, epididymal sperm maturation process, and the overall sperm fertilizing capacity.

Sex hormones and lipoproteins in adolescent male offspring of parents with premature coronary heart disease and a control group

OBJECTIVE

To compare pubertal maturation, sex steroid hormones, and lipoproteins and their interrelationships in male offspring of parents with premature coronary heart disease (cases) and a control group.

DESIGN

This was a cross-sectional comparison of cases and members of a control group 10 to 15 years of age.

SUBJECTS AND METHODS

Offspring were recruited from patient lists of area physicians. Members of the control group were recruited from area schools. Body mass (kg/m2), serum lipids, lipoproteins, apolipoproteins, estradiol, and free testosterone were measured.

RESULTS

Differences in age were not significant, but offspring were taller, heavier, and more mature. Offspring had higher total and low density lipoprotein cholesterol. Offspring had lower estradiol levels in early puberty but higher levels in late puberty. With family history and body mass in the regression models for lipid parameters, free testosterone was a significant explanatory factor for total cholesterol, low-density lipoprotein cholesterol, and high-density lipoprotein, and estradiol was a significant predictor for apolipoprotein B. The percent of the variance in the lipid parameters explained by testosterone and estradiol was small.

CONCLUSION

Sex hormone concentrations appear to be modest but significant predictors of lipoprotein and apolipoprotein concentrations in offspring and a control group in cross-sectional analysis. After controlling for pubertal maturation, hormone and lipid concentrations differed in offspring and the control group.

Predictors of lean body mass and total adipose mass in community-dwelling elderly men and women

As part of an ongoing longitudinal study, we analyzed cross-sectional data to identify the predictors of lean body mass (LBM) and total adipose mass (TAM) in community-dwelling elderly men and women. Body composition analysis was done using dual energy x-ray absorptiometry. A total 262 subjects (118 women and 144 men), 60 to 80 years of age, from the urban and suburban communities of southeastern Wisconsin were studied. In women, the age (r = -.18), body mass index (BMI) (r = .43), and waist-to-hip ratio (WHR) (r = .30), and in men, BMI (r = .45) and insulin-like growth factor-1 (IGF-1) (r = .32) were identified as predictors (P < .05) of LBM. In women, the BMI (r = .87), WHR (r = .21), and functional work capacity (VO2 max) (r = -.47), and in men, the BMI (r = .83), WHR (r = .52), dehydroepiandrosterone sulfate (DHEAS) (r = -.27), total testosterone (TT) (r = -.35), free testosterone (FT) (r = -.23), physical activity (LTE) (r = -.32), and VO2 peak (r = -.59) were identified as predictors of TAM. After partialling out age in addition to the predictors identified earlier, the VO2 peak was identified as a predictor (P < .05) of LBM in both women and men, and TT, FT, and LTE as predictors (P < .05) of LBM in men. We conclude that the BMI, WHR, and VO2 peak influences LBM and TAM in both women and men. Additionally, in men LBM and TAM is influenced by hormone profile.

Association of dehydroepiandrosterone sulfate, body composition, and physical fitness in independent community-dwelling older men and women

OBJECTIVES

To determine the association of dehydroepiandrosterone sulfate (DHEAS), body composition, and physical fitness in independent community-dwelling men and women aged 60 to 80 years.

DESIGN

Cross sectional analysis.

PARTICIPANTS

Independent men and women, 60 years of age and older, living in urban and suburban communities of Southeastern Wisconsin.

MEASUREMENTS

History, physical examination, physical activity level, and anthropometrics were measured for every subject. Total adipose mass (TAM) and lean body mass were measured using dual energy X-ray absorptiometry. Dehydroepiandrosterone sulfate, insulin-like growth factor-1 (IGF-1), total testosterone (TT), and free testosterone (FT) were measured using radioimmunoassay. Physical fitness was measured as VO2max using exercise stress tests. Blood for lipids was analyzed using standard assays.

RESULTS

In men, the DHEAS was significantly correlated to age (r = -.32), TAM (r = -.27), percent fat (r = -.30), HDL cholesterol (r = .34), TT (r = .30), VO2max (r = .23), and percent lean body mass (% LBM) (r = .33). In women, the DHEAS was not significantly correlated to any of the variables examined except body mass index (BMI) (r = .23). In men, after partialling out age, DHEAS was significantly correlated to HDL, % fat, TAM, % LBM, and TT. Multivariate analysis for men revealed that high density lipoprotein cholesterol (HDL) was the strongest predictor of serum DHEAS level, followed by % LBM, BMI, and age. The men in the highest quartile of serum DHEAS levels were different from those in the lowest quartile in terms of age, TT, FT, % fat, TAM, % LBM, HDL, and low density lipoprotein (LDL) cholesterol level. No such differences were found in the two groups of women.

CONCLUSION

In this group of independent community-dwelling older men, several factors were found to be associated with the serum DHEAS concentration, whereas in a group of older women, no such associations were identified with the exception of BMI. Men in the highest quartile of serum DHEAS level, compared with those with a serum DHEAS level in the lowest quartile, were younger, leaner, more fit, had higher TT and FT levels, and had a favorable lipid profile. No such differences were identified between the women in the highest and the lowest quartiles of serum DHEAS level.

Serum insulin-like growth factor-I and serum testosterone status of elderly men in an inpatient rehabilitation unit

This study was designed to estimate the prevalence of hyposomatomedinemia and hypogonadism in an inpatient rehabilitation unit. The authors studied healthy young men (HOM) ages 20-29 years (n=33); healthy old men (HOM) ages 59-98 years (n=27), and elderly men in an inpatient rehabilitation unit (ERM) ages 58-95 years (n=42). Serum concentrations of insulin-like growth factor (IGF-I), total testosterone (TT), and free testosterone (FT) were measured. A low IGF-I level (below the lower 2.5 percentile of HYM) occurred in 85% of the HOM and in 62.5% of the ERM. When a low IGF-I was defined as a value below the 2.5 percentile of the HOM, the prevalence in ERM was 6.2%. A low TT level (below the lower 2.5 percentile of the HOM) occurred in 78% of the HOM and in 90% of the ERM. Low TT, defined as a value below the lower 2.5 percentile of the HOM, occurred in 22% of the ERM. The results with FT were similar. In neither HOM nor ERM was IGF-I significantly correlated to TT and FT. A large percentage of HOM and ERM have severe hypogonadism (TT<193 ng/mL) as compared with HOM. The ERM had a higher prevalence of severe hypogonadism as compared with the HOM.

Bilateral effect of unilateral vasectomy on testicular testosterone biosynthesis

Twelve immature male dogs underwent a left vasectomy (group A). An additional five underwent a sham operation (group B). Sixteen weeks after the surgery, the bilateral mean values for caudal epididymal sperm content, the percentage of motile spermatozoa, intratesticular testosterone concentration, and testicular secretion of androgen-binding protein (in vitro) were significantly lower in group A. The mean peripheral serum testosterone responses 3 hours after human chorionic gonadotropin stimulation (3,000 IU) were significantly lower in group A than in group B (6.3 ng/mL v 9.5 ng/mL). These findings indicate a bilateral deficiency in both Leydig and Sertoli cell secretory function in unilaterally vasectomized dogs, resulting in impaired bilateral spermatogenesis and sperm maturation. The authors suggest that unilateral injuries of the vas deferens during hernia operations in children may result in bilateral testicular dysfunction.

Relations of endogenous anabolic hormones and physical activity to bone mineral density and lean body mass in elderly men

OBJECTIVE

It has been proposed that declining activities of the somatotrophic or gonadotrophic axes, or sedentary life style, are partial causes for geriatric losses of bone mineral density (BMD) and of lean body mass (LBM). The present study tested these hypotheses by determining, in both free-living and institutionalized elderly men, the correlations of bone mineral density (BMD), total body bone mineral content (TBBMC) and lean body mass (LBM) with the following predictor variables: age, body mass index, body weight, serum insulin-like growth factor I (IGF-I), serum testosterone, habitual physical activity and mobility.

SUBJECTS

Forty-nine independent, community-dwelling older men, and 49 men of similar age residing in two Veterans Administration extended care facilities. The age range was 58-95 years.

MEASUREMENTS

Serum IGF-I and testosterone were measured by radioimmunoassay. Habitual physical activity in the independent men and mobility in the institutionalized men were estimated by standard instruments. LBM and bone status at nine skeletal sites were determined by dual X-ray absorptiometry.

RESULTS

The BMD and TBBMC values of the free living men were 4-20% higher than those of the institutionalized men. In the independent old men, serum testosterone was the strongest predictor of BMD and TBBMC, while age was the only predictor of LBM. In the chronically institutionalized men, age, body weight and immobility were the strongest predictors of body composition, and testosterone was correlated only with femoral neck BMD.

CONCLUSIONS

In aging independent men, low levels of testosterone are associated with demineralization of the skeleton. Immobility and under-weight are associated with the osteopenia of old men residing in nursing homes. In this cross-sectional study of elderly men, there was no evidence of a relation of the somatotrophic axis to bone status or LBM, or of the gonadotrophic axis to LBM.

Low circulating levels of insulin-like growth factors and testosterone in chronically institutionalized elderly men

OBJECTIVE

To determine the prevalences of and the associations between hyposomatomedinemia and hypogonadism in healthy young men, healthy old men, and chronically institutionalized old men.

DESIGN

Survey with serial blood tests.

SETTING

Veterans Affairs nursing home and young and old men living in the community.

SUBJECTS

Three groups were studied: healthy young men (20-29 years old, n = 32), healthy old men (59-98 years old, n = 30), and chronically institutionalized old men (59-95 years old, n = 112).

MEASUREMENTS

Plasma insulin-like growth factor-I (IGF-I), total testosterone (TT), free testosterone (FT), and plasma insulin-like growth factor-II (IGF-II) were measured. In subjects with low testosterone level, serum luteinizing hormone (LH) was also determined. In a subset of chronically institutionalized old men with low IGF-I, the serum growth hormone (GH) level was analyzed during the first 4 hours of sleep.

RESULTS

A low IGF-I level (defined as a value below the lower 2.5 percentile of the comparison group) occurred in 85% of the healthy old men when compared with healthy young men (P < 0.001), in 90% of the chronically institutionalized old men when compared with healthy young men (P < 0.001), and in 26% of the chronically institutionalized old men when compared with healthy old men (P < 0.001). In chronically institutionalized old men with low IGF-I compared with healthy young men, nocturnal peaks of serum GH were < 2 ng/mL in most cases. Low TT (defined as a value below the lower 2.5 percentile of the comparison group) occurred in 86% of the healthy old men when compared with healthy young men (P < 0.001), in 88% of the chronically institutionalized old men when compared with healthy young men (P < 0.001), and in 28% of the chronically institutionalized old men when compared with healthy old men (P < 0.001). The results of FT were similar. In 80% of the institutionalized old men with low TT and FT, the serum LH level was low (< 20 mU/mL). In 53% of the institutionalized old men, the IGF-II level was below the lower 2.5 percentile of the healthy old men (P < 0.001). In both healthy and institutionalized old men, IGF-I and IGF-II levels were significantly correlated to each other (r = 0.6), but neither was significantly correlated to TT or FT. In the institutionalized old men, IGF-I was inversely correlated with age and with a diagnosis of dementia; TT and FT were inversely correlated with age and with the degree of dependency in ADL's.

CONCLUSIONS

Compared with healthy young men, most healthy old men have low serum IGF-I, TT, and FT levels. The geriatric hyposomatomedinemia and hypogonadism are more severe in institutionalized old men. In the latter group, both endocrine deficiencies are usually of central origin, but their occurrences are not significantly associated. Healthy old men usually have a low level of IGF-I compared with healthy young men, but a similar level of IGF-II; institutionalized old men are usually low in both values.

Determinants of sex hormone levels in men as useful indices in hormone-related disorders

Because the determinants of serum sex hormone levels in men have been infrequently studied, we investigated the relation of several personal characteristics to serum levels of testosterone (T), dihydrotestosterone (DHT), estrone (E1), estradiol (E2) and sex hormone-binding globulin (SHBG) among 98 Japanese American men in Hawaii, aged 52-74. The SHBG levels and T/(E1 + E2) ratios decreased progressively with increasing body mass index. The SHBG levels were also inversely associated with hematocrit levels. Serum androgen and estrogen levels did not correlate with smoking, alcohol intake, serum cholesterol, serum uric acid and blood pressure. Some of the associations observed in the present study may be implicated in the etiology of hormone-related neoplasms in men.

Effects of surgical repair of experimental left varicocele on testicular temperature, spermatogenesis, sperm maturation, endocrine function, and fertility in rabbits

To evaluate the effectiveness of surgical correction of varicocele in restoring the function of the varicocelized testicle, experimental varicoceles were created in 16 male rabbits by partly ligating the left lumbotesticular trunk. Five control rabbits received a sham operation (group A). Two months later, eight of the varicocelized rabbits underwent surgical repair by ligation and cutting of the dilated left testicular vein (group B). The remaining eight varicocelized animals did not receive any additional treatment (group C). Five months after the initial operation, group C animals had a significantly lower sperm concentration, sperm motility, bilateral testicular androgen-binding protein activity, bilateral testicular vein testosterone concentration, bilateral testicular versus intraabdominal temperature difference, and fertility when compared with groups A and B. These findings suggested that the surgical repair of an experimental varicocele in the rabbit can significantly improve the parameters indicating the harmful effects of the varicocele on the testicles.

Low bone mass in hypogonadal males. Effect of testosterone substitution therapy, a densitometric study

Sixteen (16) male patients who were suffering from hypogonadism but who were free from bone symptoms were recruited from the Andrology Clinic. Their bone mineral density (BMD) was assessed by single photon absorptiometry in the non-dominant radius, at both the distal radius (DR) (27% trabecular bone) and the midshaft radius (MR) (90% cortical bone). Measurements were carried out before and during testosterone substitution therapy. BMD was found to be lower in the subjects than in the controls, to a similar extent at both the DR (0.47 +/- 0.02 g/cm2, i.e. 83.1 +/- 4.3% of the value in the controls, or Z score -1.42 +/- 0.39; P less than 0.01) and the MR (0.68 +/- 0.02 g/cm2, i.e. 87.8 +/- 2.4% of the value in the controls, or Z score -1.49 +/- 0.33; P less than 0.01). There was no correlation between testosterone levels and BMD at either the DR or the MR at the beginning of the study. Following testosterone substitution therapy, bone mineral content (BMC) increased significantly at the DR (+5.9 +/- 1.4% per year; P less than 0.01) and at the MR (+1.1 +/- 0.9% per year; P less than 0.01). If the study is limited to the subjects who had achieved full bone age maturity before the start of therapy, the bone gain remains significant only at the DR, a site with a sizeable proportion of trabecular bone.

Elevated serum estradiol associated with increased androstenedione-testosterone ratio in adolescent males with varicocele and gynecomastia

OBJECTIVE

To investigate the testicular function in adolescents with pubertal gynecomastia associated with varicocele before and after varicocelectomy.

DESIGN AND PATIENTS

We have studied six male adolescents 15 to 19 years of age with bilateral gynecomastia. They were selected among other adolescents with gynecomastia because of the presence of visible varicoceles. All of them had normal physical examination and secondary sexual characteristics. This was prospective study of 3 months' duration. All the patients that were included finished the study.

SETTING

All the patients were evaluated in the Endocrine Clinic of Winthrop-University Hospital, a tertiary care unit.

INTERVENTION

Serum testosterone (T), androstenedione (A), and estradiol (E2) responses to the administration of human chorionic gonadotropin (hCG) 2,000 IU for 3 consecutive days before and 3 months after varicocelectomy were determined.

RESULTS

Varicocelectomy did not cause any significant changes in the basal (pre-hCG) levels of the steroid. However, the increase in T levels achieved with hCG was significantly (P less than 0.005) higher after varicocelectomy (before T, 925 +/- 212 ng%; after T, 1,649 +/- 406 ng%). Simultaneously, the stimulated levels of E2 and A were significantly lower (P less than 0.005) after varicocelectomy (E2, 62 +/- 12 pg/mL; A, 326 ng% +/- 80 ng%) than before (E2, 106 +/- 13 pg/mL; A, 580 ng% +/- 95 ng%).

CONCLUSION

The reciprocal effect on the levels of T and its immediate precursor, A, suggests an impairment of the 17-ketoreductase enzyme activity. The increased levels of E2 after hCG and its normalization after varicocelectomy suggests that varicoceles may play a pathogenetic role in the development of gynecomastia.

Regulation of myocardial isomyosin V1 in uraemic rats

Cardiac hypertrophy of various aetiologies is consistently associated with increased expression of V3 isomyosin. Uraemia is associated with cardiac hypertrophy. In the present study, we examined regulation of isomyosin in uraemic rats, using gel electrophoresis. Cardiac hypertrophy in uraemic animals was associated with a relative increase in V1 isomyosin. An increased proportion of V1 isomyosin was demonstrable 3 days after subtotal nephrectomy (NX 63.0 +/- 8.8%; control 43.6 +/- 7.2%; P less than 0.01) and persisted during uraemia of 80 days duration. Elevation of V1 isomyosin, relative to pair-fed controls, was observed in uraemic animals of various age. The proportion of V1 isomyosin changed in the same direction as controls when several manouevers were used which changed the isomyosin pattern, but the difference between uraemic animals and controls persisted. We studied the effect of carbohydrate loading or deprivation, starvation or administration of energetically inadequate diets, castration or administration of androgens and sodium depletion. With each of the above interventions, a difference between subtotally nephrectomized animals and sham-operated pair-fed control animals was statistically significant (P less than 0.05). Elevation of V1 isomyosin persisted during combined alpha and beta blockade and was still found when blood pressure was normalized by ACE inhibition using Ramipril. It is concluded that cardiac hypertrophy of uraemia differs from all other forms of cardiac hypertrophy by the occurrence of increased proportion of V1 isomyosin. The proportion of V1 isomyosin responds adequately to regulatory signals but is set at an abnormally high level.

Seasonal changes in serum gonadal steroids associated with migration, mating, and nesting in the loggerhead sea turtle (Caretta caretta)

Adult male loggerhead sea turtles, Caretta caretta, exhibited a "prenuptial" spermatogenic cycle that was coincident with increased concentrations of serum testosterone (T). Serum T was high during the months when migration and mating have been recorded for males. In contrast to females, males appear to be annual breeders. Nine reproductively active female C. caretta (as verified through laparoscopy) were tagged with sonic transmitters and were repeatedly bled prior to migration. Four months prior to the nesting season, the ovaries of reproductively active females had hundreds of vitellogenic follicles of approximately 1.5 cm in diameter (i.e., half the size of ovulatory follicles). Approximately 4-6 weeks prior to migration from feeding grounds to mating and nesting areas, serum estradiol-17 beta (E2) concentrations increased significantly and remained high for approximately 4 weeks, suggesting a period of increased vitellogenesis. During a 1- to 2-week period prior to migration, serum E2 decreased significantly, while serum T concentrations increased (at least) until the time of migration. Serum T, E2, and progesterone (PRO) were elevated during nesting if a turtle was going to nest again during that nesting season. During the last nesting of a season, turtles had low serum concentrations of T, E2, and Pro. The prenuptial pattern of gonadal recrudescence and gonadal steroid production in both male and female C. caretta contrasts with those of many temperate freshwater turtles, and this type of reproductive pattern may have been facilitated by adaptation to a tropical marine environment.

Hormonal studies and physical maturation in adolescent gynecomastia

As part of a 3-year longitudinal study of lipid and hormonal changes during puberty, 536 boys aged 10 to 15 years were prospectively followed every 6 months to assess development of gynecomastia. The overall prevalence of gynecomastia in the 377 with complete data was 48.5% (51% of white subjects and 46% of black subjects). In the majority of subjects, gynecomastia developed during mid-puberty. Gynecomastia was bilateral in 55% of subjects, on the left side in 19%, and on the right in 26%. Gynecomastia was documented for only one visit in the majority of subjects. When subjects were matched at the onset of gynecomastia for race, visit number, and pubertal rating, there were no significant differences between those with or without gynecomastia in serum estradiol level, testosterone level, estrogen/testosterone, ratio, or dehydroepiandrosterone-sulfate level. However, free testosterone level, weight, and Quetelet index were all significantly lower, and the testosterone-estrogen binding globulin level was significantly greater, in those with gynecomastia. We conclude that approximately half of adolescent boys have transient gynecomastia, usually lasting less than 1 year; those with gynecomastia enter mid-puberty at an earlier age, have a lower Quetelet index, and have lower serum free testosterone levels.

Prevention of high altitude-induced testicular disturbances by previous treatment with cyproheptadine in male rats

Male rats were exposed to 4,340 m altitude for 4 days. At this time histological alteration in the testes were observed. There were tubules with pyknotic primary spermatocytes and spermatids, necrosis of numerous cells, and sloughing of primary spermatocytes. The damaged areas were limited by normal tissue. Serum testosterone increased significantly after 4 days of exposure. Administration of an anti-serotoninergic compound, cyproheptadine (10 mg/kg body weight), prevented the high altitude-induced changes in both spermatogenesis and serum testosterone. These observations suggest that serotonin is involved in the testicular changes that occurred when rats are acutely exposed to high altitude.

Effects of acute and chronic treatments with atrial natriuretic factor (ANF) on the Leydig cells of the rat testis

Acute ANF bolus administration (40 micrograms.kg-1) did not affect secretory activity and morphology of rat Leydig cells. Prolonged (7-day) ANF infusion (20 micrograms.kg-1.h-1), on the contrary, elevated both basal and hCG-stimulated testosterone blood concentration, and caused a notable hypertrophy of rat Leydig cells. Leydig-cell hypertrophy was due to increases in the volume of all the organelles involved in cholesterol and testosterone synthesis (i.e. mitochondria, smooth endoplasmic reticulum and peroxisomes). These findings suggest that ANF, when chronically administered, is able to stimulate the growth and steroidogenic capacity of rat Leydig cells.

Sex steroid modulation of the hepatic uptake of organic anions in rat

To investigate the role of sex steroids in the sex-related difference in the hepatic uptake of organic anions, sulphobromophthalein (bromsulphalein, BSP) transport was measured in hepatocytes isolated from rats either deprived of hormonal influence by castration at prepubertal age or after hormonal substitution. In control animals, the kinetics of BSP uptake showed the presence of two components: one saturable (0-3 microM), with high affinity and low capacity, and the other linear (9-30 microM), probably related to the non-specific component of BSP uptake. Sex difference was detected only in the saturable portion of the uptake process as the apparent Km was significantly lower in females than in males (3.8 +/- 0.7 vs. 6.1 +/- 1.8 microM, mean +/- S.D. of six animals, P less than 0.01). In contrast, no difference was observed in Vmax (2.3 +/- 0.3 vs. 2.2 +/- 0.7 nmol BSP.(mg protein)-1.min-1). Castration was associated with the disappearance of the saturable uptake site and abolished the sex difference. Progesterone treatment of castrated males failed to restore the saturable kinetics of BSP uptake. In contrast, administration of oestradiol to castrated males or testosterone to castrated females did restore the saturable kinetics of the high-affinity BSP uptake. Km and Vmax were comparable to those of adult females and males, respectively, with the exception of testosterone which induced a Vmax value higher than that observed in the other groups of animals. These data suggest that the influence of oestrogen and testosterone is necessary for the expression of the high-affinity, low-capacity carrier-mediated process of hepatic BSP uptake.(ABSTRACT TRUNCATED AT 250 WORDS)

Plasma pro-opiomelanocortin fragments and adrenal steroids following administration of metyrapone to normal and hirsute women

The present study was undertaken to characterize further the adrenal abnormalities in the polycystic ovary syndrome (PCOS) and idiopathic hirsutism (IH). We have previously reported the close association of elevated estrone levels with amenorrhea in hyperandrogenemic patients. In addition we have suggested that high estrone levels in PCOS occur as a consequence of the provision of excess substrate, androstenedione, for conversion to estrone. In the present study plasma estrone levels rose following endogenous adrenal stimulation induced using metyrapone; the highest plasma estrone levels achieved were seen in patients with PCOS and occurred later than peak androstenedione levels. These findings are consistent with the hypothesis that elevated estrone levels occurring in PCOS may arise as a consequence of increased adrenal androgen secretion. In addition, we have examined ACTH and other pro-opiomelanocortin (POMC) fragments in an attempt to identify a factor responsible for the excessive adrenal androgen secretion occurring in hirsute patients. Plasma levels of ACTH, and of immunoreactive beta-endorphin and h-lipotropin were not elevated when androgen levels were raised prior to therapy, although these POMC fragments, and also the 16K fragment, rose in response to metyrapone treatment as did androgen levels. Following treatment with dexamethasone there was more profound suppression of the 16K, beta-endorphin and h-lipotropin responses to metyrapone stimulation, than of the ACTH response, as indicated by decreased POMC-fragment/ACTH ratios; this parallels the dissociation of cortisol from androgens in hirsute patients under similar conditions. However, we have not identified a POMC fragment which consistently parallels changes in androgen levels in patients with idiopathic hirsutism or PCOS.

Neonatal hemiorchidectomy of bulls alters plasma growth hormone levels and advances onset of pubertal testosterone secretion

Bovine GH and testosterone profiles were determined in plasma collected at 20 min intervals during 3 hr bleeding periods on day 25 of life and every 15 days thereafter in six intact (I) Holstein bull calves and in six others which had been hemiorchidectomized (HO) at 10 days of age. In I bulls average plasma GH concentrations varied between 7.9 and 14.5 ng/ml (P greater than 0.05) until 130 days of age, after which the GH level gradually rose (P = 0.007) to a maximum of 19.4 ng/ml on day 205 of life. Episodic release of GH was apparent in 55 day-old and older I bulls and in HO bulls of all ages. Plasma GH concentrations in HO bulls were higher than in I bulls 15 and 30 days after surgery (P = 0.07), at which times the levels in HO bulls averaged 19.6 and 22.5 ng/ml and in I bulls 10.3 and 10.2 ng/ml, respectively. Plasma GH in HO bulls again exceeded that of I bulls at ages of 130-190 days (P = 0.04). Plasma testosterone was virtually nondetectable before 130 days of age in I bulls but thereafter exhibited the typical episodic pattern. In HO bulls, plasma testosterone concentrations began to rise 15 to 30 days before those in I bulls, resulting in an age X treatment interaction (P less than 0.0001). Furthermore, average testosterone levels were higher (P = 0.07) in HO than I bulls at 235 and 250 days of age.(ABSTRACT TRUNCATED AT 250 WORDS)

Detection of neural connection to the infundibular complex by partial or complete hypothalamic deafferentation in male quail

To elucidate the stimulatory and inhibitory neural systems for photoperiodic control of avian reproduction, immature male Japanese quail were subjected to partial or complete hypothalamic deafferentation, followed by exposure to long and short photoperiods. The results indicated that when the encephalic photosensitive area (infundibular complex, INF) was preserved after hypothalamic deafferentation, birds were able to respond to long days and their gonads eventually recrudesced, and that testicular atrophy under short days was prevented by the semicircular cuts posterior to INF or by orbital enucleation. It is concluded that in male Japanese quail, INF plays the pivotal role in photoperiodic gonadostimulation and regulatory neurons in the retina and anterior hypothalamus may have neural connection to the posterior side of INF.

Bone mineral density in Addison's disease: evidence for an effect of adrenal androgens on bone mass

It is unknown whether replacement doses of cortisone acetate and the absence of the small amounts of androgens secreted by the adrenal cortex may cause osteoporosis. This was studied in 35 patients (12 men and 23 women) suffering from primary adrenocortical failure and taking cortisone acetate 25-37.5 mg and fludrocortisone 50-100 micrograms daily. Bone mineral density was measured by single photon absorptiometry at the midshaft of the radius, representing cortical bone, and at the distal part of the radius, a site with a significant trabecular component. The bone mineral density was normal in premenopausal female patients as well as in male patients, showing that replacement doses of cortisone acetate do not affect bone mass. By contrast, in postmenopausal patients there was a dramatic bone loss in addition to the physiological postmenopausal decrease in bone mass. This loss, combined with the low plasma concentrations of androstenedione, dehydroepiandrosterone, and testosterone (and low concentrations of oestrone of adrenal origin), indicates that adrenal androgens may be essential for the maintenance of bone mass in postmenopausal women with Addison's disease. In addition, these data indicate that the small amounts of androgens secreted by the adrenal cortex have a role in the maintenance of bone mass in normal postmenopausal women.

Testosterone levels change with subsistence hunting effort in !Kung San men

Although little is known empirically of the physiology of human hunting, arguments for innate biological bases of gender-dimorphic behaviors such as aggression frequently point to the role of hunting in human evolution. Study of !Kung San hunter-gatherer men demonstrated that the diurnal pattern in serum testosterone was altered during a six-day hunt, compared to pre- and post-hunt levels, due mainly to elevation of evening values. Hunting success did not correlate with any testosterone measures. The pattern of changes observed is most consistent with the known concomitants of moderate prolonged exercise.

Hepatic uptake of sex steroids in men with alcoholic cirrhosis

We attempted to determine to what extent the degree of liver function impairment might affect the hepatic uptake and, as a consequence, alter the systemic plasma levels of endogenous sex steroids in male patients with alcoholic cirrhosis. The plasma levels and hepatic uptake of the steroids dehydroepiandrosterone, androstenedione, testosterone, dihydrotestosterone, estrone, estradiol, progesterone, and 17-hydroxyprogesterone were assessed. Systemic plasma levels of testosterone and dehydroepiandrosterone were significantly (p less than 0.05) reduced, whereas those of androstenedione, estrone, and estradiol were significantly (p less than 0.05) elevated in men with alcoholic cirrhosis when compared to controls. Sex hormone binding globulin levels were also significantly elevated (p less than 0.01). The hepatic uptake of sex steroids depended on the degree of liver function impairment as shown by the linear significant relationship between their hepatic extractions and that of indocyanine green (r = 0.74-0.92, p less than 0.05; except for dihydrotestosterone, r = 0.17, not significant). In addition, the hepatic uptake of sex steroids depended on the binding affinity to sex hormone binding globulin. The higher the affinity for sex hormone binding globulin, the lower the hepatic uptake influenced by liver function impairment. It was estimated that hepatic clearances accounted for only 20%-50% of the metabolic clearance of sex steroids. No significant relationship between plasma levels of sex steroids and their hepatic clearance was found. We show here that in alcoholic cirrhosis the extent of hepatic uptake of sex steroids depends partly on the degree of liver function impairment and partly on the degree to which they are bound to sex hormone binding globulin. Production rate or peripheral metabolism, or both, rather than hepatic uptake alone may account for the altered circulating levels of sex steroids.

The effect of 4MA, a potent inhibitor of 5 alpha-reductase, on the growth of androgen-responsive human genitourinary tumors grown in athymic nude mice

The five alpha-reductase inhibitors are a newly developed family of compounds that block the intracellular conversion of testosterone (T) to dihydrotestosterone (DHT). 17-beta-N, N-Diethylcarbamoyl-4-methyl-4-aza-5-alpha-androstan-3-one (4MA), the most widely studied of these compounds, has been shown to inhibit the androgen-dependent growth of both normal animal tissues and of the Noble tumor, an experimental, hormone-responsive rat neoplasm. 4MA has been found to inhibit androgen-dependent growth without altering plasma levels of T or DHT. In the present study, we assessed the efficacy of 4MA in inhibiting the growth of PC-82 and R198, human androgen-responsive genitourinary malignancies. In the first experiment, 4MA was administered subcutaneously at a dose of 6 mg/kg/day to castrated and hormonally replaced groups of PC-82-bearing male athymic nude mice. 4MA therapy when compared to control therapy caused significant PC-82 growth inhibition in three different groups of hormonally replaced castrated mice: physiologic T-replaced (P less than .001), supraphysiologic T replaced (P less than .001), and supraphysiologic T and DHT replaced (P less than .001). There was no difference between the post therapy plasma levels of T or DHT in the control-treated and 4MA-treated mice. In the second experiment, the effect of 4MA (6 mg/kg/day S.Q.) was compared to that of castration and control therapy on the growth of R198. Both castration and 4MA therapy effectively inhibited R198 growth when compared to control therapy (P = .01 and .02, respectively), but there was no difference in the degree of growth inhibition seen with 4MA or castration (P = .45). Castration and 4MA-therapy significantly lowered plasma T levels when compared to control therapy; castration also significantly lowered plasma DHT levels, while 4MA and control therapy did not. These studies suggest that 4MA is effective in inhibiting the growth of human androgen-responsive tumors grown in athymic nude mice and that further studies with other 5 alpha-reductase inhibitors are indicated.

Technical difficulties of selective venous blood sampling in the differential diagnosis of female hyperandrogenism

To determine glandular steroid release of adrenals and ovaries in female hyperandrogenism, a standardized method for percutaneous transfemoral venous blood sampling was developed. In eight volunteers and 67 patients, catheterization was performed during the early follicular phase (days 3-7; between 8 and 10 a.m.) to reduce interference from cyclic and circadian variations of secretion. Serial samplings reduced the episodic effluent changes. Anatomical variations and collateral flow as well as stress effects and the dosage of contrast media were studied. During catheterization, peripheral cortisol levels did not differ significantly from control groups. Collaterals had no effect on hormone levels. Contrast media increased cortisol effluent levels only when they were sampled following venography. Four-vessel venous sampling was found to be indicated if peripheral testosterone was more than 1.5 ng/ml and/or dehydroepiandrosterone sulfate more than 6,700 ng/ml. If an ovarian (adrenal)/peripheral gradient of testosterone exceeded 2.7 ng/ml, surgical intervention for tumor removal at the site of hormone excess was felt to be necessary.

Pituitary extract of the ricefield eel Monopterus albus (Synbranchidae, Teleostei) exhibits gonadotropic activity in the classes Mammalia, Aves, Reptilia and Amphibia

Pituitary extract of the ricefield eel Monopterus albus demonstrated gonadotropic activity in mammals and non-mammalian vertebrates. Using the rat as the recipient, FSH activity was detected in Monopterus pituitaries in the HCG augmentation test and LH activity in the ovarian ascorbic acid depletion test. Cyclic AMP level in superovulated ovaries, ovarian lactate production and glucose uptake in vitro, plasma testosterone level in males, testicular enzymes, ventral prostate weight and other androgen-dependent parameters were stimulated after treatment with Monopterus pituitary extract. Testicular and ovarian 32P5+ uptake in the chick, testicular weight in the grass turtle Chinemys reevesi, and ovulation in the amphibians Xenopus laevis and Rana tigrina were enhanced. Both the FSH-like and LH-like activities in Monopterus pituitaries were sensitive to proteolytic enzymes and chemicals that attack the disulfide linkage, carbohydrate moiety, tyrosine, tryptophan and histidine residues. This constitutes the first report of dual gonadotropic activities elicited by a teleost pituitary extract in the mammal in vivo.