A clinical trial of injectable testosterone undecanoate as a potential male contraceptive in normal Chinese men

This is a pilot dose-finding study of spermatogenic suppression using testosterone undecanoate (TU) injections alone in normal Chinese men. Thirty-two healthy men were recruited. Volunteers underwent pretreatment evaluation, then a treatment period in which group I (n = 13) received 500 mg TU, group II (n = 12) received 1000 mg TU, and group III (n = 7) received placebo, respectively, at monthly intervals during the treatment period (or until azoospermia was achieved). Thereafter, they underwent a recovery period until all parameters returned to pretreatment levels. Eleven of 12 volunteers in the 500-mg TU group, and all volunteers in the 1000-mg TU group became azoospermic. Faster suppression of spermatogenesis was achieved in the 1000-mg TU group. Serum testosterone increased significantly in the higher dose group at weeks 8 and 12, but remained within the normal range. Mean serum LH and FSH were profoundly suppressed by both doses to undetectable levels at week 16. TU injections did not cause a significant change in high density lipoprotein cholesterol levels. No serious side-effects were found. We conclude that both dosages of TU can effectively, safely, and reversibly suppress spermatogenesis in normal Chinese men.

A lower dosage levonorgestrel and testosterone combination effectively suppresses spermatogenesis and circulating gonadotropin levels with fewer metabolic effects than higher dosage combinations

Studies using exogenous high-dosage testosterone (T) or a combination regimen of physiologic T plus high-dosage levonorgestrel (LNG) administration in normal men have shown that oligoazoospermia (<3 million/mL) or azoospermia can be achieved in the majority of the men. However, these hormonal regimens have been associated with significant weight gain and suppression of serum high-density lipoprotein (HDL) cholesterol levels. We hypothesized that a combination of physiologic exogenous testosterone and lower dosage LNG would result in uniform severe oligoazoospermia or azoospermia in normal men but would cause fewer adverse metabolic side effects. We conducted a randomized, placebo-controlled, single-blind trial comparing 6 months of T enanthate (100 mg IM, weekly) plus LNG, 125 microg by mouth, daily (LNG 125; n = 18) or LNG, 250 microg by mouth, daily (LNG 250; n = 18) and compared these regimens with our previous study of the same dosage of T enanthate combined with placebo LNG (LNG 0; n = 18) or with 500 mg of LNG (LNG= 500; n = 18). All three combination regimens of T enanthate and LNG suppressed spermatogenesis more rapidly and resulted in significantly more uniform severe oligoazoospermia (<1 million/mL) than the T-alone regimen. Severe oligoazoospermia was achieved in 89% of the LNG 125, 89% of the LNG 250, and 78% of the LNG 500 groups, respectively, versus 56% of the men in LNG 0 (P < 0.05 for the combination groups vs. LNG 0), but there were no significant differences between the combination regimens (P = NS). All four groups gained significant weight compared with their baselines, although the gain tended to be greater as the dosage of LNG increased (2.0+/-0.9, 2.9+/-1.1, 3.6+/-1.0, and 5.4+/-1.0 kg gained, compared with baseline in the LNG 0, 125, 250, and 500 groups respectively; P < 0.05 compared with baseline). Serum levels of HDL cholesterol decreased in all of the groups, but the effect was larger as the dosage of LNG increased (4+/-4% vs. 13+/-4%, 20+/-3%, and 22+/-4% decrease in HDL levels from baseline in the LNG 0, LNG 125, LNG 250, and LNG 500 groups respectively; P = 0.06 for LNG 125 compared with LNG 0, and P < 0.05 for LNG 250 and LNG 500 compared with LNG 0). We conclude that 1) the combination of physiologic exogenous T enanthate and LNG suppresses spermatogenesis more effectively than T enanthate alone and that 2) the combination regimen of T enanthate plus lower dosage LNG suppresses sperm production comparably to T enanthate plus higher dosage LNG, while causing less weight gain and HDL cholesterol suppression. A combination regimen of physiologic testosterone plus a low dosage of levonorgestrel offers great promise as a safe and effective male contraceptive regimen.

Prostate-sparing effects in primates of the potent androgen 7alpha-methyl-19-nortestosterone: a potential alternative to testosterone for androgen replacement and male contraception

7alpha-Methyl-19-nortestosterone (MENT) is a potent synthetic androgen that cannot be converted to dihydrotestosterone. In this study we determined the relative androgenic, antigonadotropic, and anabolic potencies of testosterone vs. MENT in the nonhuman primate M. fascicularis. In castrated monkeys, dose-response relationships were generated for the effects of testosterone and MENT on gonadotropin levels, prostate growth, body weight, and lipid metabolism. In a pilot study, four monkeys were castrated, and magnetic resonance imaging (MRI) was used to document a 50% loss of prostate volume within 8 weeks, verifying that MRI is a reliable means to measure prostate size in this species. Two additional groups of six monkeys each were then castrated and serially administered four graded dosages of testosterone or MENT via osmotic minipumps over 20 weeks. Complete suppression of LH was achieved with a minimum of 0.3 mg/day MENT, compared to 3.0 mg/day testosterone. MENT supported body weight 10 times more potently than did testosterone. Baseline prostate volumes were maintained with 0.1-0.2 mg/day MENT vs. 0.3 mg/day testosterone. Thus, in monkeys, MENT is 10 times more potent than testosterone with regard to the clinically desirable end points of gonadotropin suppression and anabolism, but only twice as potent at stimulating prostate growth. These results suggest that MENT may have a wider therapeutic index than testosterone for human androgen replacement and male contraception.

A pharmacokinetic study of injectable testosterone undecanoate in hypogonadal men

Testosterone undecanoate (TU) provides testosterone (T) replacement for hypogonadal men when administered orally but requires multiple doses per day and produces widely variable serum T levels. We investigated the pharmacokinetics of a newly available TU preparation administered by intramuscular injection to hypogonadal men. Eight patients with Klinefelter's syndrome received either 500 mg or 1,000 mg of TU by intramuscular injection; 3 months later, the other dose was given to each man (except to one, who did not receive the 1,000-mg dose). Serum levels of reproductive hormones were measured at regular intervals before and after the injections. Mean serum T levels increased significantly at the end of the first week, from less than 10 nmol/L to 47.8+/-10.1 and 54.2+/-4.8 nmol/ L for the lower and higher doses, respectively. Thereafter, serum T levels decreased progressively and reached the lower-normal limit for adult men by day 50 to 60. Pharmacokinetic analysis showed a terminal elimination half-life of 18.3+/-2.3 and 23.7+/-2.7 days and showed a mean residence time of 21.7+/-1.1 and 23.0+/-0.8 days for the lower and higher doses, respectively. The area under the serum T concentration-time curve and the T-distribution value related to serum T concentration were significantly higher following the 1,000-mg dose than following the 500-mg dose. The 500-mg dose, when given as the second injection, yielded optimal pharmacokinetics (defined as mean peak T values not exceeding the normal range and persistence of normal levels for at least 7 weeks), suggesting that repeated injections of 500 mg at 6-8-week intervals may provide optimal T replacement. The mean serum levels of estradiol were normalized following the injections, and prolactin levels were normal throughout the study. Significant decrease of serum luteinizing hormone (LH) and follicle-stimulating hormone (FSH) levels was observed, with the decrease in LH levels being more pronounced. There were no significant differences in serum LH and FSH levels between the two doses. Sex hormone-binding globulin (SHBG) levels before any T therapy were near the upper limit of normal for adult men and were reduced by approximately 50% just prior to the second dose of TU. The decreased SHBG levels produced by the first TU injection could have led to lower peak total T levels and to a more rapid clearance of T following the second TU injection. We conclude that single-dose injections of TU to hypogonadal men can maintain serum T concentration within the normal range for at least 7 weeks without immediately apparent side effects. It is likely that this form of T would require injections only at 6-8-week or longer intervals, not at the 2-week intervals necessary with currently used T esters (enanthate and cypionate). This injectable TU preparation may provide improved substitution therapy for male hypogonadism and, in addition, may be developed as an androgen component of male contraceptives.

The use of testosterone as a male contraceptive

Testosterone functions as a contraceptive by suppressing secretion of the pituitary gonadotropins luteinizing hormone and follicle stimulating hormone. Low levels of these hormones decrease endogenous testosterone secretion from the testis and deprive developing sperm of the signals required for normal maturation. Interference with sperm maturation causes a decline in sperm production and can lead to reversible infertility in men, raising the possibility that testosterone could be utilized in a commercially available contraceptive. To this end, testosterone has been studied alone and in combination with either gonadotropin releasing hormone analogues or progestins in efforts to improve its contraceptive efficacy. In this chapter, we will review efforts to use testosterone to create a safe, convenient, efficacious contraceptive method for men.

Suppression of spermatogenesis in man induced by Nal-Glu gonadotropin releasing hormone antagonist and testosterone enanthate (TE) is maintained by TE alone

GnRH antagonists plus testosterone (T) suppress LH and FSH levels and inhibit spermatogenesis to azoospermia or severe oligozoospermia. High-dose T treatment alone has been shown to be an effective male contraceptive (contraceptive efficacy rate of 1.4 per 100 person yr). Combined GnRH antagonist and T induces azoospermia more rapidly and at a higher incidence than T alone; this combination has therefore been proposed as a prototype male contraceptive. However, because GnRH antagonists are expensive to synthesize and difficult to deliver, it would be desirable to rapidly suppress sperm counts to low levels with GnRH antagonist plus T and maintain azoospermia or severe oligozoospermia with T alone. In this study, 15 healthy men (age 21-41 yr) with normal semen analyses were treated with T enanthate (TE) 100 mg im/week plus 10 mg Nal-Glu GnRH antagonist sc daily for 12 weeks to induce azoospermia or severe oligozoospermia. At 12-16 weeks, 10 of 15 subjects had zero sperm counts, and 14 of 15 had sperm counts less than 3 x 10(6)/mL. The 14 who were suppressed on combined treatment were maintained on TE alone (100 mg/week im) for an additional 20 weeks. Thirteen of 14 subjects in the TE alone phase had sperm counts maintained at less than 3 x 10(6)/mL for 20 weeks. Ten remained persistently azoospermic or had sperm concentration of 0.1 x 10(6)/mL once during maintenance. Mean LH and FSH levels in the subjects were suppressed to 0.4+/-0.2 IU/L and 0.5+/-0.2 IU/L in the induction phase, which was maintained in the maintenance phase. The 1 subject who failed to suppress sperm counts during induction had serum LH and FSH reduced to 0.3 and 0.5 IU/L, respectively. The subject who failed to maintenance had LH and FSH suppressed to 1.0 and 0.2 IU/L, respectively, during the induction phase but these rose to 1.6 and 2.1 IU/L, respectively, during maintenance. Failure to suppress or maintain low sperm counts may be related to incomplete suppression of serum LH and FSH levels. We conclude that sperm counts suppressed with GnRH antagonist plus T can be maintained with relatively low dose TE treatment alone. This concept should be explored further in the development of effective, safe, and affordable hormonal male contraceptives.

Klinefelter syndrome

Klinefelter syndrome is the most common sex chromosome disorder. Affected males carry an additional X chromosome, which results in male hypogonadism, androgen deficiency, and impaired spermatogenesis. Some patients may exhibit all of the classic signs of this disorder, including gynecomastia, small testes, sparse body hair, tallness, and infertility, whereas others, because of the wide variability in clinical expression, lack many of these features. Treatment consists of testosterone replacement therapy to correct the androgen deficiency and to provide patients with appropriate virilization. This therapy also has positive effects on mood and self-esteem and has been shown to protect against osteoporosis, although it will not reverse infertility. Although the diagnosis of Klinefelter syndrome is now made definitively using chromosomal karyotyping, revealing in most instances a 47,XXY genotype, the diagnosis also can be made using a careful history and results of a physical examination, with the hallmark being small, firm testes. As it affects 1 in 500 male patients and presents with a variety of clinical features, primary care physicians should be familiar with this condition.

Low dose of cyproterone acetate and testosterone enanthate for contraception in men

After a control phase, 10 normal men received cyproterone acetate (CPA) at a dose of 25 mg/day (CPA-25; n=5) or 12.5 mg/day (CPA-12.5; n=5) plus testosterone enanthate (TE) 100 mg/week, for 16 weeks. Throughout the study sperm counts were performed every 2 weeks, and luteinizing hormone (LH), follicle stimulating hormone (FSH), testosterone, biochemical and haematological tests were performed every 4 weeks. All five men in group CPA-25 and three men in group CPA-12.5 achieved azoospermia. One man in group CPA-25 was azoospermic by week 12 of hormone administration, but had a sperm count of 0.1 x 10(6)/ml at week 16. Time to azoospermia was 9.0+/-1.3 and 8.7+/-0.7 weeks in groups CPA-25 and CPA-12.5 respectively. Gonadotrophins were decreased by week 4 of hormone administration, remained around the minimum detectability of the assay for the duration of hormone administration and returned to baseline after stopping hormone administration. Testosterone values did not change. No change in any biochemical parameters was found. Haematological parameters were decreased at week 16 of hormone administration and returned to baseline after stopping hormone administration. In conclusion, these results suggest that an hormonal regimen consisting of testosterone plus a progestin with anti-androgenic properties holds promise as an effective, safe and reversible male contraceptive.

Immature spermatids are not prevalent in semen from men who are receiving androgen-based contraceptive regimens

OBJECTIVE

To determine whether immature spermatids increase in semen in response to hormonal contraceptive treatments. Such a finding would support the existence of a defect in spermiogenesis, which in turn may explain the reported variability in sperm output.

DESIGN

Semen smears were obtained from healthy men undergoing randomized control trials of T plus progestin contraceptive treatments.

PATIENT(S)

Healthy men (21-49 years) with normal semen analyses received T (50-100 mg IM weekly) in combination with either desogestrel (150-300 microg daily, n = 5) or levonorgestrel (125-250 microg daily, n = 10) for 24 weeks. Semen smears were made during spermatogenic suppression and recovery. Nine control subjects were also assessed.

MAIN OUTCOME MEASURE(S)

Semen analyses were performed using World Health Organization criteria. Immature spermatids and white blood cells in semen were identified by immunostaining with monoclonal antibodies to the human intra-acrosomal antigen SP-10 and the ubiquitous white cell CD-45 antigen, respectively.

RESULT(S)

In a total of 14 normal ejaculates (9 control and 5 pretreatment) 74+/-14 million/mL sperm (mean+/-SEM) were seen together with a few immature spermatids (0.69+/-0.20 million/mL). During contraceptive treatments, spermatid number decreased in parallel with the sperm concentration and spermatids disappeared in most subjects. No significant changes were seen in either leukocyte or immunonegative round cell concentration (0.41+/-0.25 and 0.25+/-0.09 million/mL in controls, respectively) in response to treatments.

CONCLUSION(S)

Spermatid sloughing, as assessed by the ejaculation of immature spermatids, is not a feature of T-induced spermatogenic regression in men; rather, the decline in both mature and immature germ cells in the ejaculate probably results from a decline in the number of precursor cells, ultimately resulting in severe oligo- or azoospermia. Detailed studies on the sites of spermatogenic interruption are required to understand the variability in responses seen after contraceptive therapies in men.

An oral regimen of cyproterone acetate and testosterone undecanoate for spermatogenic suppression in men

OBJECTIVE

To test the effectiveness, safety, and reversibility of the combined administration of cyproterone acetate and T undecanoate.

DESIGN

Open clinical trial.

SETTING

Healthy volunteers in an academic research environment.

PATIENT(S)

Eight healthy men, aged 25-42 years were selected.

INTERVENTION(S)

Cyproterone acetate, 12.5 mg, and T undecanoate, 80 mg, were administered orally twice daily for 16 weeks.

MAIN OUTCOME MEASURE(S)

Semen analyses every 2 weeks; physical examination, chemistries, hematology, prostatic-specific antigen, gonadotropins and T levels, and a questionnaire on sexual and behavioral function every 4 weeks.

RESULT(S)

In all subjects a profound suppression of spermatogenesis occurred; one subject became azoospermic, five subjects had sperm counts of < or = 3 x 10(6)/mL, and in two subjects sperm counts were 4 and 6 x 10(6)/mL in week 16. Sperm counts returned to baseline in all men after hormone administration was discontinued. No changes in metabolic parameters and total prostatic-specific antigen were detected. Hemoglobin and hematocrit decreased statistically significantly at week 16 of treatment and returned to baseline by week 12 of recovery. There was no change in sexual function or behavior.

CONCLUSION(S)

The oral administration of T undecanoate plus cyproterone acetate induces a profound suppression of spermatogenesis with no major adverse effects. These data suggest the feasibility of oral contraception in men.

Quantitative (stereological) study of the normal spermatogenesis in the adult monkey (Macaca fascicularis)

Germ cell and Sertoli cell numbers were estimated in six normal adult monkeys (Macaca fascicularis) using a contemporary unbiased and efficient stereological method--the optical disector. The data was used to assess the efficiency of spermatogenesis from type B spermatogonia to elongated spermatids. Animals underwent orchidectomy, and the right testis (volume 17.5 +/- 1.7 cm3 [mean +/- SEM], range 13.2-25.1 cm3) was fixed in Bouin's fluid. Blocks were embedded in methacrylate resin and germ cells were counted in thick (25 microm) sections using the optical disector in conjunction with a systematic uniform random-sampling protocol. The total numbers of Sertoli cells and all germ cells per testis were 566 +/- 43 (419-683) million and 12.8 +/- 1.6 (9.0-20.2) billion, respectively. On average, one Sertoli cell supported 12.4 +/- 1.9 (range 8.2-18.4) step 1-12 spermatids, 3.1 +/- 0.4 (2.3-4.5) pachytene spermatocytes, and 23.7 +/- 4.1 (15.0-39.0) total germ cells. Sertoli cell number correlated poorly with both testicular size (correlation coefficient r = -0.12) and germ cell numbers (r = -0.35 with total germ cell number). However, testicular size had a consistent and significant correlation with germ cell numbers (r = 0.97 with total germ cell number). The conversion ratio of pachytene spermatocytes to step 1-12 spermatids was 3.94 +/- 0.19, which is close to the theoretical maximum of 4. Similarly, the conversion between other cell types was consistently close to the maximum theoretical value. We conclude that the efficiency of spermatogenesis in the adult monkey is high, with stepwise conversion being consistently close to the maximal values. The capacity of Sertoli cells to support a cohort of germ cells varies widely between monkeys. Although absolute number of cells per testis is always the preferred parameter, it cannot always be obtained in an experimental situation where cost and ethical constraints mean that biopsies, rather than whole testes, are collected. Thus, if absolute data on germ cell numbers are not available, experimental outcomes impacting on cells beyond preleptonene spermatocytes may be best expressed in terms of changes in germ cell conversion rather than the traditional germ cell: Sertoli cell ratio.

Serum inhibin B levels reflect Sertoli cell function in normal men and men with testicular dysfunction

We used a recently developed ELISA format to test the hypothesis that inhibin B is the physiologically active form of inhibin in men. We measured and compared inhibin A, inhibin B, and pro-alpha-C-related immunoreactive peptides (pro-alpha-C-RI) in normal men before and after perturbations of their gonadotropin levels and baseline values in normal men and men with various disturbances of the hypothalamic-pituitary-testicular axis including men with idiopathic hypogonadotropic hypogonadism, infertile men with elevated FSH, men with Klinefelter's syndrome, and orchidectomized men. Mean serum inhibin concentrations were significantly higher in normal men than untreated men with idiopathic hypogonadotropic hypogonadism, infertile men with elevated FSH, untreated men with Klinefelter's syndrome, and orchidectomized men (187 +/- 28 vs 45 +/- 11, 37 +/- 6, 11 +/- 3, and < or = 10 pg/mL, respectively; P < 0.05). Inhibin B levels were below the limit of detection in all of the orchidectomized men. Pro-alpha-C-RI levels were detectable in all men studied including the orchidectomized men, and no significant differences in the pro-alpha-C-RI levels were noted between the normal men and men with various testicular diseases were noted except that orchidectomized men had significantly lower pro-alpha-C-RI levels than all other groups (P < 0.05). Inhibin A was undetectable in all men tested in this study. Six normal men who were administered exogenous levonorgestrel and testosterone had significantly lower serum gonadotropin, inhibin B, and pro-alpha-C-RI levels during the treatment period than the control and recovery periods (P < 0.05). Ten normal men who were administered human recombinant FSH had significantly higher peak serum FSH (21.85 +/- 3.23 IU/L vs. 3.01 +/- 0.51 IU/L), inhibin B (311 +/- 88 pg/mL vs. 151 +/- 23 pg/mL) and pro-alpha-C-RI (646 +/- 69 vs. 402 +/- 38 pg/mL) levels during the treatment period than the baseline values (P < 0.05). We conclude that inhibin B is a unique testicular product that is not detectable in the sera of orchidectomized men, is responsive to FSH stimulation, and has a reciprocal relationship with serum FSH levels in men with various forms of testicular disease. Therefore, inhibin B is likely to be the physiologically important form of inhibin in men.

A combined regimen of cyproterone acetate and testosterone enanthate as a potentially highly effective male contraceptive

In this study we tested the effectiveness of the combined administration of cyproterone acetate (CPA) and testosterone enanthate (TE) in suppressing spermatogenesis. After a control phase of 3 months, 15 normal men were randomized to receive TE (100 mg/week) plus CPA at a dose of 100 mg/day (CPA-100; n = 5) or 50 mg/day (CPA-50; n = 5) or TE (100 mg/week) alone (n = 5) for 16 weeks. Semen analysis was performed every 2 weeks. Every 4 weeks, fasting blood samples were drawn for the measurement of LH, FSH, testosterone, estradiol, and biochemical and hematological parameters; subjects underwent a physical examination; and they and their partners filled in a sexual and behavioral questionnaire. Regardless of the dose, each of the 10 subjects receiving CPA plus TE became azoospermic, whereas only 3 of 5 subjects treated with TE alone achieved azoospermia. Times to azoospermia were 6.8 +/- 0.5, 8.4 +/- 1.0, and 14.0 +/- 1.2 weeks in groups CPA-100, CPA-50, and TE alone, respectively (P = NS). Throughout treatment, both gonadotropins tended to be higher in the TE alone group than in the other groups. This difference was mostly due to the higher gonadotropin levels present in the 2 men treated with TE alone that remained oligospermic. No difference in testosterone or estradiol levels was found among the groups. No significant change in lipoprotein levels or liver function tests could be detected. In the CPA-100 and CPA-50 groups, hemoglobin, hematocrit, and red blood cells were lower at the end of the treatment phase, whereas no change was detected in TE alone group. A tendency for a decrease in body weight was detected in subjects treated with CPA, whereas there was no change in subjects receiving TE alone. At the end of the treatment phase, a decrease in testis size was present in all groups. There was no significant change in sexual function, aggressive behavior, mood states, or satisfaction with relationship in any group. These results suggest that the combined administration of CPA and TE is very effective in suppressing spermatogenesis and may represent a promising regimen for reversible contraception in males.

Testosterone-induced suppression of lipoprotein(a) in normal men; relation to basal lipoprotein(a) level

The concentration of lipoprotein(a) [Lp(a)] in human plasma is largely genetically determined and is inversely correlated to the size of apolipoprotein(a) [apo(a)]. Additionally, Lp(a) values are relatively stable within individuals and are only marginally susceptible to therapeutic treatment. The aim of our study was to evaluate the effect of exogenous testosterone on plasma Lp(a) concentration. The study was carried out on 19 healthy men who were receiving weekly intramuscular injections of 200 mg testosterone enanthate. Lp(a) values were determined at multiple time-points by a double monoclonal antibody-based enzyme immunoassay. This method is not sensitive to variation in Lp(a) size and the values are expressed in nmol/l. Apo(a) size isoforms were determined by agarose gel electrophoresis followed by immunoblotting. No correlation was found between the baseline Lp(a) values and the baseline values of testosterone or estradiol. The Lp(a) response to testosterone treatment varied widely among subjects and was dependent upon the pretreatment Lp(a) concentration. For 10 subjects with low Lp(a) values (< 25 nmol/l), no significant decrease in Lp(a) was observed while, for the nine individuals with Lp(a) values > 25 nmol/l, there was a significant and consistent reduction in Lp(a) ranging from 25 to 59%. Lp(a) levels returned to baseline values following cessation of testosterone administration. Apo(a) size polymorphism did not appear to play a role in the determination of Lp(a) response to testosterone.

Inhibin-B: a likely candidate for the physiologically important form of inhibin in men

Inhibin is a glycoprotein hormone that is defined on the basis of inhibition of pituitary FSH production, However, previous data have not shown any correlation between RIA measurements of inhibin and FSH in men. New enzyme-linked immunosorbent assays, specific for inhibin A, inhibin B, and inhibin pro-alphaC-related immunoreactivity, were applied to the measurement of inhibin in 32 healthy men. Further measurements of inhibin B and pro-alphaC-RI were carried out on groups of men exhibiting a wide range of FSH concentrations, including semen donors, infertile men, and men with elevated FSH concentrations. Inhibin A was undetectable (<2 pg/mL) in all men studied. The healthy men studied all had measurable concentrations of inhibin B (135.6 pg/mL; confidence interval, 108.4-169.4) and pro-alphaC-RI (426.3 pg/mL; confidence interval, 378.4-480.2). A close negative correlation was found between the inhibin B and FSH concentrations in the semen donors (r = -0.69; P < 0.001), the infertile men (r = -0.81; P < 0.001), and the men with elevated FSH concentrations (r = -0.54; P < 0.01), but not in a group of healthy volunteers (r = -0.08; P = NS). No correlation was observed between concentrations of pro-alphaC-RI and FSH in any of the groups studied. These results strongly suggest that the physiologically important form of inhibin in men is inhibin B, which has a critical effect on FSH release. Inhibin B may offer a clinically useful serum marker of testicular function.

Reproductive aging: accelerated ovarian follicular development associated with a monotropic follicle-stimulating hormone rise in normal older women

Women experience a decline in fertility that precedes the menopause by several years. Previous studies have demonstrated a monotropic rise in FSH associated with reproductive aging: however, the mechanism of this rise and its role in the aging process are poorly understood. The purpose of this study was to characterize ovarian follicular development and ovarian hormone secretion in older reproductive age women. Sixteen women, aged 40-45 yr, with regular ovulatory cycles were studied. The control group consisted of 12 ovulatory women, aged 20-25 yr. Serum obtained by daily blood sampling was analyzed for FSH, LH, estradiol (E), progesterone, and inhibin (Monash polyclonal assay). Follicle growth and ovulation were documented by transvaginal ultrasound. Older women had significantly higher levels of FSH throughout the menstrual cycle. E, progesterone, LH, and inhibin levels did not differ between the two age groups when compared relative to the day of the LH surge. Ultrasound revealed normal growth, size, and collapse of a dominant follicle in all subjects. Older women had significantly shorter follicular phase length associated with an early acute rise in follicular phase E, reflecting accelerated development of a dominant follicle. We conclude that older reproductive age women have accelerated development of a dominant follicle in the presence of the monotropic FSH rise. This is manifested as a shortened follicular phase and elevated follicular phase E. The fact that ovarian steroid and inhibin secretion were similar to those in the younger women suggests that elevated FSH in women of advanced reproductive age may represent a primary neuroendocrine change associated with reproductive aging.

The anterior pituitary response to a gonadotropin-releasing hormone challenge test in normal older reproductive-age women

OBJECTIVE

To assess the pituitary responsiveness to GnRH stimulation of premenopausal women relative to age.

DESIGN

Older and younger reproductive-age women underwent the GnRH stimulation test in the early follicular phase of the menstrual cycle.

SETTING

Female subjects in an academic research environment.

PATIENTS

Women aged 21 to 44 years consisting of normal volunteers and infertility patients.

INTERVENTIONS

Gonadotropin-releasing hormone was administered intravenously between days 2 and 4 of the menstrual cycle. Blood samples were collected from -20 minutes before to 120 minutes after administration.

MAIN OUTCOME MEASURE

Luteinizing hormone, FSH, inhibin, and E2 levels.

RESULTS

No significant difference in baseline values existed between older and younger women with regard to LH, inhibin, and E2, but basal FSH levels were higher in older women. A significantly diminished percent of LH and percent FSH change above baseline occurred 30 minutes after GnRH administration in the older women compared with younger women. No change in inhibin or E2 levels could be detected during the sampling period.

CONCLUSIONS

The present study demonstrates marked attenuation of the acute pituitary LH response (sensitivity) to GnRH stimulation in older women when compared with a younger cohort.

Combined administration of levonorgestrel and testosterone induces more rapid and effective suppression of spermatogenesis than testosterone alone: a promising male contraceptive approach

Studies using high dose testosterone (T) administration in normal men as a male contraceptive have resulted in azoospermia rates of only 50-70%. Previous studies of T and progestogen combinations have shown comparable rates of azoospermia, but have been uncontrolled or used T in doses less than that associated with maximal suppression of sperm production. We conducted a randomized, placebo-controlled, single blind trial comparing 6 months of T enanthate administration (100 mg, im, weekly) with the same dose of T enanthate in conjunction with the progestogen levonorgestrel (LNG; 500 micrograms, orally, daily) in 36 normal men, aged 20-42 yr (n = 18 in each group). The primary end points were induction of azoospermia or severe oligospermia (< 3 million sperm/mL). The combination of T plus LNG was much more effective in suppressing sperm production than T alone. Sixty-seven percent of the T plus LNG group (12 of 18) and 33% of the T alone group (6 of 18) achieved azoospermia by 6 months (P = 0.06). Severe oligospermia or azoospermia developed in 94% of the T plus LNG (17 of 18) group compared to 61% of the T alone group (11 of 18; P < 0.05). T plus LNG also suppressed sperm production more rapidly than T alone. Time to azoospermia was 9.9 +/- 1.0 vs. 15.3 +/- 1.9 weeks in the T plus LNG and T alone groups, respectively (mean +/- SEM; P < 0.05). Serum high density lipoprotein cholesterol decreased 21.7 +/- 3.6% in men given T plus LNG (P < 0.05), compared to only a 1.8 +/- 3.8% decrease in men in the T alone group. Average weight gain was 5.3 +/- 0.8 kg in the T plus LNG group and 2.3 +/- 0.9 kg in the T alone group (P < 0.05). Acne and increase in hemoglobin were similar in the two groups. We conclude that combination hormonal therapy with T plus a progestogen might offer a reversible male contraceptive approach with a more rapid onset of action and more reliable induction of both azoospermia and severe oligospermia than T alone.

Annual patterns of luteinizing hormone, follicle stimulating hormone, testosterone and inhibin in normal men

Reproductive functions in most animals demonstrate seasonal fluctuations that allow young to be born at a time of the year favourable for their survival. Whether there is a seasonal change in the human reproductive system is unclear. In the present study, we measured serum concentrations of luteinizing hormone, follicle stimulating hormone, testosterone and inhibin in the same 16 normal men sampled monthly for 1 year. A statistically significant increase in all four measured hormones was found in June, with a nadir in August. Our findings suggest that a circannual rhythm of gonadotrophins and testicular hormones exists in normal men. The mechanism leading to this rhythm and the importance of the rhythm in human biology are unknown.