Effects of levonorgestrel butanoate alone and in combination with testosterone buciclate on spermatogenesis in the bonnet monkey.

The spermatogenic effects of levonorgestrel butanoate were studied in adult male bonnet monkeys when administered alone and in combination with testosterone buciclate. Levonorgestrel butanoate (0.25, 1.0 and 2.5 mg kg(-1)) given as two injections on days 0 and 60 (groups II, III, IV) resulted in thickening and folding of the basement membrane and disruption of cell associations in groups III and IV (on day 120). In group II, no apparent changes in testicular histology were observed. When these doses of levonorgestrel butanoate were combined with 40 mg of testosterone buciclate (groups V, VI, VII), maximum changes were seen in group VI in which all stages of spermatogenesis were absent on day 120 except for a small number of spermatogonia. The changes caused by lower dose (group V) and higher dose (group VII) of levonorgestrel butanoate were less prominent than in group VI. A significant decrease in the number of dark A (Ad) and B spermatogonia was observed in all groups except for Ad spermatogonia on day 120 in group V, B spermatogonia on day 60 in group IV and B spermatogonia on day 120 in group III. A significant decrease in pachytene spermatocytes was seen on day 120 in groups V only. Early spermatids showed a significant decrease only in groups V and VII on day 120 of treatment. Advanced spermatids were suppressed significantly in group IV on day 60 and in groups IV and V on day 120. These data indicate that levonorgestrel butanoate (1.0 mg kg(-1)) in combination with 40 mg of testosterone buciclate was the most effective treatment in suppressing spermatogenesis. The site of action of this combination regimen is at the level of renewing Ad spermatogonia.

Evaluation of the ability of levonorgestrel butanoate alone, or in combination with testosterone buciclate, to suppress spermatogenesis in the bonnet monkey (Macaca radiata).

Levonorgestrel butanoate, 0.25, 1.0 and 2.5 mg/kg, administered as two injections 60 days apart (groups II, III, IV), failed to suppress spermatogenesis consistently and uniformly in adult bonnet monkeys (group size, n=6) compared to controls (group I). Levonorgestrel butanoate at the same doses combined with two simultaneous injections of 40 mg testosterone buciclate (groups V, VI, VII), consistently suppressed spermatogenesis in the period 60-240 days and in most animals to azoospermia or severe oligozoospermia (<5 x 106/mL) during days 90-210. The degree and duration of suppression were greatest in group VI. Sperm motility declined in all treated animals and spermatozoa in the semen of animals from groups V and VI lost all progressive motility in the period 60-150 and 60-210 days, respectively. The changes in testosterone levels were similar in groups V and VI, increasing within 24 h after the combined injection to reach a peak by day 28 followed by a sharp decrease until day 67. The second injection increased testosterone levels by a lesser degree to peak levels on day 81. In group VII, testosterone levels decreased until day 59 after the first injection but increased to a maximum on day 81 after the second injection followed by a gradual decrease until day 150 to below baseline values. Peak levels of serum levonorgestrel were observed 1-7 days after injection of levonorgestrel butanoate alone. Clearance of the drug was slow, being detectable in the circulation until day 330 of the 360 day study period in the high dose group. Dose-response increases to peak levels of levonorgestrel were attained on day 7 in groups V, VI and VII, after the first injection. After the second injection, peak levels were seen on day 61 in groups V and VI and on day 81 in group VII. Levonorgestrel was no longer detectable in blood in groups V and VI by days 210 and 300, respectively, but small circulating amounts remained in group VII at the conclusion of the study on day 360. This study indicates that when levonorgestrel butanoate is combined with a long-acting androgen and injected at two-monthly intervals, effective and reversible suppression of spermatogenesis is achieved.

The contribution of Asian scientists to global research in andrology.

AIM: To present a personal account of the involvement of the World Health Organization (WHO) in the collaborative development in Asia of those areas of andrology concerned with male contraception and reproductive health. METHODS: The andrology training through workshops and institution support undertaken by the WHO Human Reproduction Programme (HRP) and how they contributed to the strengthening of andrology research in Asia are summarised. RESULTS: The author' s experience and the Asian scientific contributions to the global research in the following areas are reviewed: the safety of vasectomy and the development of new methods of vas occlusion; gossypol and its failure to become a safe, reversible male antifertility drug; Tripterygium and whether its pure extracts will pass through the appropriate toxicology and phased clinical studies to become acceptable contraceptive drugs; hormonal methods of contraception for men. CONCLUSION: The WHO policy of research capacity building through training and institution strengthening, together with the collaboration of Asian andrologists, has created strong National institutions now able to direct their own programmes of research in clinical and scientific andrology.

Endocrine and reproductive health status of men who had experienced short-term radiation exposure at Chernobyl.

Hormonal and semen parameters in 416 men aged 25-45 years were examined: 328 were men who cleaned the territory around the Chernobyl nuclear reactor (called 'liquidators') and 88 were healthy age-matched controls. The dose of radiation received by the liquidators was 0.16 +/- 0.08 Gy. LH, FSH, prolactin, testosterone and cortisol levels were assayed using WHO-matched reagents. Semen analyses were performed according to the WHO Manual (1992). The mean concentration of all hormones in liquidators and controls were within the WHO-defined normal range. The mean levels of LH and cortisol in liquidators were significantly lower (p = 0.013 and p < 0.001, respectively) and testosterone significantly higher (p = 0.023) than in controls. The variations in hormone levels in liquidators were not correlated with the acquired doses of radiation as measured by personal dosimeters (film badges). Semen parameters in a subgroup of 70 liquidators were within the normal WHO-defined range. The percentage of normal forms of spermatozoa in liquidators (35.0 +/- 13.1%) was significantly lower (p < 0.015) than in a control group (42.8 +/- 8.9%). The study has shown that exposure of men to relatively short-term radiation did not cause long-lasting disruption of their endocrine status and spermatogenesis. The study was 7-9 years retrospective and it is therefore impossible to infer what the immediate effects of the radiation exposure were on these parameters.

Gossypol: reasons for its failure to be accepted as a safe, reversible male antifertility drug.

Following clinical trials conducted in China in the 1970s, gossypol was proposed as a drug for male contraceptive use. This review summarizes the extensive investigations on formal animal toxicology and on the recovery of fertility in men after stopping gossypol treatment which led to the decision by the Special Programme of Research, Development and Research Training in Human Reproduction (HRP) at the World Health Organization (WHO), that gossypol would not be acceptable as an antifertility drug. It is concluded that the assessment of gossypol reinforces the mandatory requirement that future contraceptive drugs must be developed by the established routes of appropriate animal toxicology and phased clinical studies.

PIP: There have been reports that studies conducted in China confirm the efficacy of gossypol as a male antifertility drug. This paper presents the extensive investigations on formal animal toxicology and on the recovery of male fertility after cessation of gossypol use. Studies conducted by the International Organization for Chemical Sciences in Development showed that 40 of the 70 highly purified, novel structural forms of gossypol were no more active than gossypol. Experiments conducted on Sprague-Dawley rats and cynomolgous monkeys confirm that either (-) or (+) gossypol is too toxic to be developed for human contraception. Among the side effects associated with the use of gossypol, the most serious was hypokalemic paralysis, although differences in reported incidences could be attributed to the regional differences in dietary intake of potassium and genetic predisposition. On the other hand, studies that examine the risk of permanent sterility among healthy reproductive males were confirmed by two separate studies, which found an incidence of 25% irreversible sterility. The failure of recovery among those who stopped gossypol use could be attributed to longer treatment, greater total dose of gossypol, smaller testicular volume, and elevated follicle stimulating hormone concentrations. The cessation of clinical studies on gossypol because of increased risk in irreversible testicular damage and low therapeutic ratio is recommended.

Effects of testosterone enanthate in normal men: experience from a multicenter contraceptive efficacy study. World Health Organization Task Force on Methods for the Regulation of Male Fertility.

OBJECTIVE: To evaluate the secondary impact of a prototype androgen contraceptive regimen on physical, metabolic and behavioral variables. DESIGN: Prospective, open, noncomparative contraceptive efficacy study. SETTING: International multicenter study comprising 10 centers in seven countries. SUBJECTS: Two hundred seventy-one healthy men, age 31.8 +/- 5.4 years (mean +/- SD), range 21 to 45 years. INTERVENTIONS: Weekly IM injections of 200 mg T enanthate. MAIN OUTCOME MEASURES: Adverse effects and discontinuations; biochemical and hematologic changes and interpopulation differences. RESULTS: Chinese subjects were shorter and lighter and their baseline hemoglobin, plasma lipid, and liver enzyme levels were lower than in non-Chinese subjects. The most common side effects were painful injections, acne, fatigue, and weight gain. Gynecomastia and prostate problems were detected in 24 and 9 men, respectively, though no men stopped injections for such reasons. Testosterone enanthate increased body weight, hemoglobin, and urea but decreased testicular volume and creatinine. Plasma triglyceride, cholesterol, and low-density lipoprotein cholesterol were unchanged; high-density lipoprotein cholesterol decreased by 14% to 18% in non-Chinese but was unchanged in Chinese men. Liver transaminases were increased by 36% to 51% in Chinese but were unchanged in non-Chinese subjects. These T enanthate-induced effects were reversible within 6 months of stopping injections and were not related to the duration of T exposure. CONCLUSIONS: Testosterone enanthate administration in a contraceptive trial produced significant but reversible effects on skin, muscle, liver, lipid metabolism, and hemopoietic functions that varied between population groups. These effects reflect the relatively high peak levels and fluctuations of plasma T produced by the weekly T enanthate regimen rather than an inherent feature of hormonal male contraception. The results highlight the need for long-acting preparations of T with more stable delivery kinetics.

PIP: At 10 centers in 7 countries, researchers conducted a clinical trial of weekly intramuscular injections of 200 mg testosterone (T) enanthate in 271 healthy fertile men, 21-45 years old, to evaluate the secondary impact of this prototype male contraceptive regimen on various physical, metabolic, and behavioral variables. They also focused on the differences between Chinese men and non-Chinese men as well as their similarities. At baseline, Chinese men were shorter, weighed less, and had lower levels of hemoglobin, plasma lipids, and liver enzymes than non-Chinese men (p 0.05). The overall leading side effects were acne (80), fatigue (22), painful injections (15), and weight gain (12). 24 men, all of whom were non-Chinese men, experienced excessive development of the male mammary glands (gynecomastia). Nine men (1 Chinese, 8 non-Chinese) had prostate problems. No man discontinued T enanthate injections for gynecomastia or prostate problems, however. T enanthate contributed to an increased body weight (by 5% at 360 days) and increased levels of hemoglobin (by 7.6% at 360 days) and creatinine while it contributed to a decrease in testicular volume (by 26.2% at 360 days) and in urea level. T enanthate appeared to have no effect on plasma triglyceride, cholesterol, and low density lipoprotein (HDL) cholesterol. It was associated with a decrease of 14-18% in HDL-cholesterol in non-Chinese men but it had no effect on HDL-cholesterol in Chinese men. T enanthate increased liver transaminase by 36-51% in Chinese men but it had no effect on these enzymes in non-Chinese men. Regardless of length of exposure to T enanthate, the T enanthate-induced changes were reversible within 6 months. These findings suggest that T enanthate produced significant but reversible metabolic and physical effects that differed between Chinese and non-Chinese men. These effects are a result of the relatively high peak levels and fluctuations of plasma T produced by the weekly injections rather than an inherent feature of hormonal male contraception.

A non-human primate study (baboon; Papio hamadryas) to determine if a long-acting progestogen, levonorgestrel butanoate, combined with a long-acting androgen, testosterone buciclate, can suppress spermatogenesis: I. Dose-finding study.

This study in adult male baboons was conducted to establish the dose of a long-acting progestogen, levonorgestrel butanoate, and that of a long-acting androgen, testosterone buciclate, which, when combined, would achieve optimal and prolonged suppression of spermatogenesis. Two intramuscular injections of levonorgestrel butanoate at 3-month intervals and in the dose range 1-8 mg/kg reduced sperm production and plasma concentrations of testosterone, LH and FSH for periods of up to 6 months. The suppression of sperm production was greatest and most prolonged in the 4 mg/kg group. Two intramuscular injections of testosterone buciclate at 3-month intervals, and at doses of 4 and 8 mg/kg, induced variable changes in circulating levels of testosterone, elevated by the higher dose, and caused sperm suppression, in some animals to azoospermia. It was concluded that 8 mg/kg testosterone buciclate would provide adequate androgen replacement when combined with 4 mg/kg levonorgestrel butanoate as a putative male contraceptive regimen.

A non-human primate study (baboon; Papio hamadryas) to determine if a long-acting progestogen, levonorgestrel butanoate, combined with a long-acting androgen, testosterone buciclate, can suppress spermatogenesis: II. Efficacy study.

Two combined injections of levonorgestrel butanoate (4 mg/kg) and testosterone buciclate (8 mg/kg) at 3-month intervals to adult male baboons initiated a decrease in sperm concentration from baseline values of 490x10(6)/ml to minimum values of 17x10(6/ml. This suppression was sustained until week 32, during which time between one and three azoospermic samples were collected from each of four out of five treated baboons in the period 10-24 weeks. Circulating plasma levels of LH and testosterone decreased to approximately 20-75% of baseline values. Plasma levels of cortisol declined to significantly reduced levels at weeks 22 and 36-44. All values returned to the baseline range by week 48. The combined administration of progestogen and androgen induced a more marked and sustained suppression to severe oligozoospermia or azoospermia than did the equivalent dose of progestogen alone (Goncharov et al., 1995). Although the dose of testosterone buciclate used did not maintain peripheral levels of testosterone in the normal range, it did not restimulate spermatogenesis. It was concluded that a combination drug regimen based on the novel long-acting levonorgestrel and testosterone esters could provide a contraceptive option for men.

Factors in nonuniform induction of azoospermia by testosterone enanthate in normal men. World Health Organization Task Force on Methods for the Regulation of Male Fertility.

OBJECTIVE: To identify factors differentiating men becoming azoospermic from those remaining oligozoospermic within 6 months of T treatment. DESIGN: Prospective, open, noncomparative contraceptive efficacy study. SETTING: International multicenter study of 271 men in 10 centers in seven countries. PATIENTS: Data from 157 achieving azoospermia and 68 remaining oligozoospermic after 6 months of treatment were analyzed. The remaining 46 men were excluded as having unclassifiable suppression status due to discontinuation before completion of suppression. INTERVENTIONS: Weekly IM injections of 200 mg T enanthate. MAIN OUTCOME MEASURES: Anthropometric, seminal, hormonal, and biochemical data obtained before, during, and after treatment as potential predictors of consistent azoospermia. RESULTS: Azoospermic men had [1] faster rates of fall in sperm output and, after a delay of 75 +/- 4 days (mean +/- SE) for sperm to reappear in the ejaculate, exhibited a faster rate of recovery of sperm output; [2] higher pretreatment levels of FSH (mean +/- SE; 3.7 +/- 0.3 versus 2.7 +/- 0.4 mIU/mL [conversion factor to SI units, 1.00]); and [3] (if treated for > 15 months) a prolonged after treatment rebound in gonadotropins compared with nonazoospermic men. There were no other differences in pretreatment variables or plasma T levels and changes in androgen-sensitive markers during treatment. None of the variables explained the higher rates of azoospermia among men in Chinese (91%, n = 3) compared with non-Chinese centers (60%, n = 7). CONCLUSION: Nonuniformity of T-induced azoospermia among healthy fertile men is not due to anthropometric or ethnic differences, to variations in androgen effects, or to poor compliance with treatment. The heterogeneity in individual susceptibility to T-induced azoospermia is most consistent with quantitative differences in the hormonal regulation of spermatogenesis and is likely to be evident with other hormonal methods for male contraception.

Male fertility regulation: the challenges for the year 2000.

The search for new, safe, effective and reversible contraceptive methods for men is being pursued by several agencies. The most likely developments before the year 2000 would appear to be: the introduction of more easily reversed procedures of vas occlusion; hormonal means of sperm suppression based on infrequent injections of androgens either alone or combined with other gonadotrophin-suppressing agents. Methods based on new drugs or vaccines are unlikely to be developed by the end of the decade. Research is needed to understand the basis of the differences in efficacy of contraceptive steroids in men of different ethnic origin. Equally there is a need to monitor the safety and acceptability of hormonal methods for men. New targets for drug intervention should be pursued through support of basic science, taking advantage of modern cellular and molecular biological techniques. Finally, the subject of Andrology needs to be strengthened throughout the world so that scientists in developing countries can participate fully in this work.

PIP: The search for new, safe, effective, and reversible contraceptive methods for men as pursued by several agencies and probable future developments until the year 2000 is reviewed. A WHO consultation between vasectomy and the risk of cancer of the prostate or testis is unlikely and changes in family planning policies are unwarranted. Research in China has led to the ligation of the vas by percutaneous injection of sclerosing agents through a puncture opening. The suppression of secretion of either both luteinizing hormone and follicle-stimulating hormone (FSH) or of FSH alone; the recovery of circulating androgen to physiological levels; and the assessment of the functional capacity of residual sperm. Hormonal methods comprise the contraceptive efficacy of testosterone enanthate-induced azoospermia and oligozoospermia; and gonadotropin-releasing hormone analogue-androgen combinations. A large number of non-hormonal chemical agents lead to total spermatogenic arrest and to irreversible sterility. Gossypol was studied as an antifertility agent in clinical studies on more than 8000 Chinese men, but its use for contraception was halted owing to the high incidence of irreversibility and serious side effects such as hypokalemia. Among drugs and plant products for inhibition of sperm maturation, Chinese investigation showed that a multiglycoside extract of the plant Tripterygium wilfordii caused reductions in sperm motility and concentration in patients. A program established between Chinese, Thai, and UK centers aims to isolate pure compounds extracted from the plant for antifertility actions. In regard to contraceptive vaccines, passive or active immunization against FSH has resulted in significant decreases in sperm counts in macaque monkeys with inconsistent effects on fertility.

The safety of vasectomy: recent concerns.

Vasectomy has been accepted for family planning by approximately 42 million couples worldwide, the majority of whom live in developing countries. It is a highly reliable and safe contraceptive method, which has been extensively studied. Recently, however, renewed concerns have been raised about a possible effect between vasectomy and cancer of the prostate many years after the procedure has been performed. These concerns are based on research conducted in the USA, where there is a high and rising incidence of prostate cancer. This review discusses the evidence for this association and its potential impact in developing countries. The factors influencing the development and growth of prostate cancer are poorly understood and complicate any research into risk factors for the disease. Overall incidences of prostate cancer in some developed countries, such as the USA, are fifty times higher than in some developing countries, such as China. The majority of epidemiological studies on the relationship between vasectomy and prostate cancer have been based in the USA, but the findings are inconsistent and the reported associations weak. On the basis of currently available data, no changes in family planning policies with regard to vasectomy are warranted, but the concerns raised by these studies require that research into any possible association be undertaken in developing countries where vasectomy is widely practised.

PIP: About 42 million couples worldwide, most of whom live in developing countries, have chosen vasectomy as their family planning (FP) method. There has been considerable research on the short and longterm safety of vasectomy. In the 1970s, research on rhesus monkeys indicated an increased risk of atherosclerosis, possible due to an increased level of antisperm antibodies. Later research on vasectomized men in developed and developing countries did not support these animal studies. Epidemiological studies in the US and Scotland showed an increased risk of testicular cancer in vasectomized men. A WHO meeting reviewed these studies and found no logical mechanism for this association. Later research found that vasectomy does not cause testicular tumors or accelerate the development of existing neoplasms. 2 studies in the US in 1990 suggested that vasectomy increases the risk of prostate cancer many years after the procedure. No studies since then have substantiated these findings. Besides, no known biological mechanism or hypothesis can explain the association. Vasectomy and prostate cancer specialists at a meeting of the US National Institutes of Health in March, 1993, agreed that physicians should continue to perform vasectomies and need not change clinical practice. Extrapolation of the US results to other countries is not logical, particularly to countries where prostate cancer is rare. Nevertheless, these recent reports will probably affect FP programs and acceptance of vasectomy in countries where vasectomy is common. Still, the evidence does not justify changes pertaining to vasectomy in national FP programs. Research on the longterm safety of vasectomy should be conducted. In conclusion, vasectomy is still a simple, safe, and very effective FP method.

Thermoregulation of the scrotum and testis: studies in animals and significance for man.

This article reviews the extensive information available from experiments on animals concerning the thermal monitoring provided by the scrotum. Cutaneous temperature receptors initiate responses which follow unique pathways and undergo "switching" processing within the central nervous system. These pathways evoke reflex responses which are subject to control from receptors in other regions of the body, including the skin and temperature sensitive neurones in the brain and spinal cord. The local thermoregulatory responses of the scrotum, e.g., sweating and vasomotor changes, clearly have a role to play in the protection of the testis against temperature elevation in both man and animals. It is as yet more difficult to propose how general reflex responses may be of benefit in the protection of spermatogenesis against heat damage. This meeting should provide the stimulus for further work. The need is urgent since it may also provide a means to apply this knowledge to a better understanding of male infertility and possibly to speed the development of male methods of fertility regulation.

Effects of passive immunization against oestradiol-17 beta on some endocrine values of the male lamb.

Passive immunization of male lambs against oestradiol-17 beta from 2 to 16 weeks of age significantly elevated androgen concentrations in plasma and depressed the median eminence content of dopamine. Removal of endogenous oestrogens had no significant effects on plasma FSH, LH or prolactin concentrations or on testicular growth and hypothalamic content of GnRH. These results suggest that endogenous oestrogens may indirectly suppress testicular androgen secretion by exerting a stimulatory influence on hypothalamic dopaminergic neurones, which in turn may inhibit GnRH secretion by the median eminence.