Male hormonal contraception: concept proven, product in sight?

Progesterone: A Steroid with Wide Range of Effects in Physiology as Well as Human Medicine

Progesterone is a steroid hormone traditionally linked with female fertility and pregnancy. In current reproductive medicine, progesterone and its analogues play crucial roles. While the discovery of its effects has a long history, over recent decades, various novel actions of this interesting steroid have been documented, of which its neuro- and immunoprotective activities are the most widely discussed. Discoveries of the novel biological activities of progesterone have also driven research and development in the field of progesterone analogues used in human medicine. Progestogen treatment has traditionally and predominately been used in maintaining pregnancy, the prevention of preterm labor, various gynecological pathologies, and in lowering the negative effects of menopause. However, there are also various other medical fields where progesterone and its analogues could find application in the future. The aim of this work is to show the mechanisms of action of progesterone and its metabolites, the physiological and pharmacological actions of progesterone and its synthetic analogues in human medicine, as well as the impacts of its production and use on the environment.

Retinoic acid and/or progesterone differentiate mouse induced pluripotent stem cells into male germ cells in vitro

Numerous reagents were employed for differentiating induced pluripotent stem cells (iPSCs) into male germ cells; however, the induction procedure was ineffective. The aim of this study was to improve the in vitro differentiation of mice iPSCs (miPSCs) into male germ cells with retinoic acid (RA) and progesterone (P). miPSCs were differentiated to embryoid bodies (EBs) in suspension with RA with or without progesterone for 0, 4, and 7 days. Then, the expression of certain genes at different stages of male germ cell development including Ddx4 (pre meiosis), Stra8 (meiosis), AKAP3 (post meiosis), and Mvh protein was examined in RNA and/or protein levels by real-time polymerase chain reaction or flow cytometry, respectively. The Stra8 gene expression increased in the RA groups on all days. But, expression of this gene declined in RA + P groups. In addition, an increased expression of Ddx4 gene was observed on day 0 in the P group. Also, a significant upregulation was observed in the expression of AKAP3 gene in the RA + P group on days 0 and 4. However, gene expression decreased in P and RA groups on day 7. The expression of Mvh protein significantly increased in the RA group on day 7. The Mvh expression was also enhanced in the P group on day 4, but it decreased on day 7, while this protein upregulated on day 0 and 7 in the RA + P group. The miPSCs have the capacity for in vitro differentiation into male germ cells by RA and/or progesterone. However, the effects of these inducers depend on the type of combination and an effective time.

Cyclophilin D participates in the inhibitory effect of high-fat diet on the expression of steroidogenic acute regulatory protein

OBJECTIVE

The high-fat diet (HFD)-induced obesity is responsible for the testosterone deficiency (TD). However, the mechanism remains unknown. Mitochondrial homeostasis is proved to be important for maintaining the function of steroidogenic acute regulatory protein (StAR), the first rate-limiting enzyme in testosterone synthesis. As the key regulator of mitochondrial membrane permeability, cyclophilin D (CypD) plays a crucial role in maintaining mitochondrial function. In this study, we sought to elucidate the role of CypD in the expression of StAR affected by HFD.

METHODS

To analyse the influence of CypD on StAR in vivo and in vitro, mouse models of HFD, CypD overexpression and CypD knockout (Ppif-/- ) as well as Leydig cells treated with palmitic acid (PA) and CypD overexpression plasmids were examined with an array of metabolic, mitochondrial function and molecular assays.

RESULTS

Compared with the normal diet mice, consistent with reduced testosterone in testes, the expressions of StAR in both mRNA and protein levels in HFD mice were down-regulated, while expressions of CypD were up-regulated. High-fat intake impaired mitochondrial function with the decrease in StAR in Leydig cells. Overexpression of CypD inhibited StAR expressions in vivo and in vitro. Compared with C57BL/6 mice with HFD, expressions of StAR were improved in Ppif-/- mice with HFD.

CONCLUSIONS

Mitochondrial CypD involved in the inhibitory effect of HFD on StAR expression in testes.

Regulation of the blood-testis barrier

The purpose of this review is to describe the endocrine and local testicular factors that contribute to the regulation of the blood-testis barrier (BTB), using information gained from in vivo and in vitro models of BTB formation during/after puberty, and from the maintenance of BTB function during adulthood. In vivo the BTB, in part comprised of tight junctions between adjacent somatic Sertoli cells, compartmentalizes meiotic spermatocytes and post-meiotic spermatids away from the vasculature, and therefore prevents autoantibody production by the immune system against these immunogenic germ cells. This adluminal compartment also features a unique biochemical milieu required for the completion of germ cell development. During the normal process of spermatogenesis, earlier germ cells continually cross into the adluminal compartment, but the regulatory mechanisms and changes in junctional proteins that allow this translocation step without causing a 'leak' remain poorly understood. Recent data describing the roles of FSH and androgen on the regulation of Sertoli cell tight junctions and tight junction proteins will be discussed, followed by an examination of the role of paracrine factors, including members of the TGFβ superfamily (TGFβ3, activin A) and retinoid signalling, as potential mediators of junction assembly and disassembly during the translocation process.

CURRENT STATE OF THE MALE INFERTILITY PROBLEM:THE REVIEW OF EUROPEAN ASSOCIATION OF UROLOGY CLINICAL GUIDELINES

The article highlights the problem of male infertility on the basis of review of the latest guidelines of European Association of urology

Endocrine control of spermatogenesis: Role of FSH and LH/ testosterone

Evaluation of testicular functions (production of sperm and androgens) is an important aspect of preclinical safety assessment and testicular toxicity is comparatively far more common than ovarian toxicity. This chapter focuses (1) on the histological sequelae of disturbed reproductive endocrinology in rat, dog and nonhuman primates and (2) provides a review of our current understanding of the roles of gonadotropins and androgens. The response of the rodent testis to endocrine disturbances is clearly different from that of dog and primates with different germ cell types and spermatogenic stages being affected initially and also that the end-stage spermatogenic involution is more pronounced in dog and primates compared to rodents. Luteinizing hormone (LH)/testosterone and follicle-stimulating hormone (FSH) are the pivotal endocrine factors controlling testicular functions. The relative importance of either hormone is somewhat different between rodents and primates. Generally, however, both LH/testosterone and FSH are necessary for quantitatively normal spermatogenesis, at least in non-seasonal species.

Association of progesterone receptor gene polymorphism with male infertility and clinical outcome of ICSI

PURPOSE

To investigate the association of Progesterone Receptor (PR) gene variations and male infertility

METHODS

DNA extraction, PCR and sequencing of PR gene, PROGINS insertion by PCR. Association of the variations with seminal parameters and outcomes of ICSI.

RESULTS

Four known SNPs in the PR gene were identified in the study of which three (rs3740753, rs1042838, rs104283) were co-inherited and in complete linkage disequilibrium with the PROGINS Alu insertion. There were no differences in their frequencies between fertile and infertile males. The rs2020880 was found at a very low frequency only in the controls but not in the infertile subjects. The sperm counts, fertilization rate, embryo quality or pregnancy rates were not different in individuals with or without PROGINS allele.

CONCLUSION

PR gene alterations are not associated with male infertility or ICSI outcome.

Demand for male contraception

The biological basis for male contraception was established decades ago, but despite promising breakthroughs and the financial burden men increasingly bear due to better enforcement of child support policies, no viable alternative to the condom has been brought to market. Men who wish to control their fertility must rely on female compliance with contraceptives, barrier methods, vasectomy or abstinence. Over the last 10 years, the pharmaceutical industry has abandoned most of its investment in the field, leaving only nonprofit organisations and public entities pursuing male contraception. Leading explanations are uncertain forecasts of market demand pitted against the need for critical investments to demonstrate the safety of existing candidate products. This paper explores the developments and challenges in male contraception research. We produce preliminary estimates of potential market size for a safe and effective male contraceptive based on available data to estimate the potential market for a novel male method.

Impact of male hormonal contraception on prostate androgens and androgen action in healthy men: a randomized, controlled trial

CONTEXT

Male hormonal contraception (MHC) combines hypothalamic-pituitary-gonadal axis blockade with exogenous androgen delivery to maintain extragonadal androgen end-organ effects. Concern exists that MHC may adversely impact prostate health.

OBJECTIVE

The objective of the study was to determine the molecular impact of MHC on intraprostatic androgen concentrations and androgen action.

DESIGN

This was a single-blind, randomized, placebo-controlled study.

SETTING

The study was conducted at an academic medical center.

PARTICIPANTS

32 healthy men aged 25-55 yr participated in the study.

INTERVENTION

Interventions included placebo, daily transdermal testosterone (T) (T-gel), T-gel + depomedroxyprogesterone acetate (T+DMPA), or T-gel + dutasteride daily (T+D) for 12 wk, and prostate biopsy during treatment wk 10.

MAIN OUTCOME MEASURES

Serum and prostate androgen concentrations and prostate epithelial-cell gene expression were measured.

RESULTS

Thirty men completed the study. Serum T levels were significantly increased in T-gel and T+D groups compared with baseline (P < 0.05) but were decreased with the addition of DMPA. Intraprostatic androgens were no different from placebo with T-gel treatment. Addition of DMPA to T resulted in 40% lower intraprostatic dihydrotestosterone (DHT) concentration (P = 0.0273 vs. placebo), whereas combining dutasteride with T resulted in a 90% decrease in intraprostatic DHT (P = 0.0012), 11-fold increased intraprostatic T (P = 0.0011), and 7-fold increased intraprostatic androstenedione (P = 0.0011). Significant differences in global or androgen-regulated prostate epithelial-cell gene expression were not observed. Androgen-regulated gene expression correlated with epithelial-cell androgen receptor and prostatic DHT in placebo, T-gel, and T+DMPA arms and with T and androstenedione levels in the T+D arm.

CONCLUSIONS

MHC regimens do not markedly alter gene expression in benign prostate epithelium, suggesting they may not alter risk of prostate disease. Longer-term studies examining the impact of MHC on prostate health are needed.

Attitudes towards the male contraceptive pill: psychosocial and cultural explanations for delaying a marketable product

Even though years of research on the male contraceptive pill have been conducted, a marketable product is still absent from the arsenal of male and female products of contraception. In this paper, the following psychosocial and cultural factors have been elicited from the literature in order to reveal explanations for this delay: acceptability, trust, fear of side-effects, perceptions of contraceptive responsibility and fear of losing connotations of masculinity. Regardless of cultural variation, overall there seems to be a positive attitude towards the acceptability of male contraceptive for both males and females, especially males in stable relationships. Some indication shows that the media have played an important role in distorting the results of research regarding male and female trust. Ongoing and future researches into several projects on psychosocial and cultural factors are described.

Deficits in spermatogenesis but not neurogenesis are alleviated by chronic testosterone therapy in R6/1 Huntington's disease mice

Despite the well established central pathophysiology of Huntington's disease (HD), less is known about systemic impairments that are emerging as significant contributors to the morbidity of this neurodegenerative condition. Given the evidence of neuroendocrine dysfunction in HD patients and the pro-neural properties of sex-hormones, we explored the therapeutic potential of hormone therapy in the HD R6/1 mouse model (HD mice). HD mice over-express exon-1 of the defective human HD gene and replicate many of the clinical behavioural, biochemical and physiological impairments. Seven-week-old HD and wild-type littermate mice had either saline (control) or testosterone (treatment; 160μg/day over 90days) pellets implanted s.c. and were subsequently subjected to behavioural, molecular and cellular analysis. Separate mice were used to establish a decrease in serum testosterone concentrations in HD mice at 12weeks of age. Baseline serum testosterone was significantly reduced in control 19-week-old HD mice, whereas treatment significantly raised serum testosterone in both wild-type and HD mice. Testosterone treatment had a limited effect on the development of rotarod deficiencies in HD mice and no effect on progressive body weight loss or the development of central mutant huntingtin-containing aggregates. Testosterone treatment induced hypo-locomotion in both genotypes. Deficits in hippocampal-dependent cognition and neurogenesis were not rescued in testosterone-treated HD mice. By contrast, wild-type-treatment mice experienced significantly increased neuronal survival and differentiation. Testosterone treatment in HD mice did rescue androgen receptor levels in the hippocampus and testes, significantly improved severe testicular atrophy and restored spermatogenesis. We conclude that chronic testosterone provides systemic efficacy in treating spermatogenesis deficits and testicular atrophy but not central cellular and behavioural pathologies in R6/1 HD mice.

Extended intervention time and evaluation of sperm suppression by dienogest plus testosterone undecanoate in male rat

BACKGROUND

The potential of using dienogest [DNG, 40 mg/kg body weight (bw)] plus testosterone undecanoate (TU, 25 mg/kg bw) in rats for development of a once-a-month male hormonal contraceptive has been reported earlier in our laboratories.

STUDY DESIGN

In the present study, we report a separate efficacy evaluation of the same combination, DNG (40 mg/kg bw) and TU (25 mg/kg bw) in which interval of drug administration has been extended further to 45 and 60 days instead of every 30 days.

RESULTS

Complete sperm suppression was observed in rats sacrificed either 60 or 90 days after DNG+TU administration, for two injections at 45-day interval. The neutral α-glucosidase activity in these treated rats remained in the normal range. Germ cell loss due to apoptosis was frequently observed both after 60 or 90 days of combination treatment. Significant decline in serum gonadotropin and testosterone, both serum and intratesticular levels, were observed in the treated rats. Following stoppage of treatment (given at 45-day interval) after two (0 and 45 days) or three injections (0, 45 and 90 days), complete restoration of spermatogenesis was observed by 120 and 165 days, respectively. The sperm suppression, however, could not be sustained when the period of combined drug administration was extended from every 45 to 60 days.

CONCLUSIONS

Dienogest plus testosterone undecanoate in the above doses retained contraceptive effectiveness when administered every 45 days but not 60 days. The spermatogenic arrest was completely reversible once drug treatment is stopped. The dose and the frequency of intervention can be extrapolated in future clinical trials.

Gonadotropins regulate rat testicular tight junctions in vivo

Sertoli cell tight junctions (TJs) are an essential component of the blood-testis barrier required for spermatogenesis; however, the role of gonadotropins in their maintenance is unknown. This study aimed to investigate the effect of gonadotropin suppression and short-term replacement on TJ function and TJ protein (occludin and claudin-11) expression and localization, in an adult rat model in vivo. Rats (n = 10/group) received the GnRH antagonist, acyline, for 7 wk to suppress gonadotropins. Three groups then received for 7 d: 1) human recombinant FSH, 2) human chorionic gonadotropin (hCG) and rat FSH antibody (to study testicular androgen stimulation alone), and 3) hCG alone (to study testicular androgen and pituitary FSH production). TJ proteins were assessed by real-time PCR, Western blot analysis, and immunohistochemistry, whereas TJ function was assessed with a biotin permeation tracer. Acyline treatment significantly reduced testis weights, serum androgens, LH and FSH, and adluminal germ cells (pachytene spermatocyte, round and elongating spermatids). In contrast to controls, acyline induced seminiferous tubule permeability to biotin, loss of tubule lumens, and loss of occludin, but redistribution of claudin-11, immunostaining. Short-term hormone replacement stimulated significant recoveries in adluminal germ cell numbers. In hCG +/- FSH antibody-treated rats, occludin and claudin-11 protein relocalized at the TJ, but such relocalization was minimal with FSH alone. Tubule lumens also reappeared, but most tubules remained permeable to biotin tracer, despite the presence of occludin. It is concluded that gonadotropins maintain Sertoli cell TJs in the adult rat via a mechanism that includes the localization of occludin and claudin-11 at functional TJs.

Trials for development of once-a-month injectable, hormonal male contraceptive using dienogest plus testosterone undecanoate: dose standardization, efficacy and reversibility studies in rats

BACKGROUND

The study was conducted to test the potential of using dienogest (DNG) plus testosterone undecanoate (TU) in rats for development of a once-a-month injectable male hormonal contraceptive.

STUDY DESIGN

Dose selection studies were initiated with administration of DNG in three different doses of 20, 30 and 40 mg/kg body weight (bw) per week plus TU 25 mg/kg bw once in every 6 weeks. Status of spermatogenesis and sperm count in epididymis was evaluated. The frequency of DNG intervention was later extended to every 2- and 4-week intervals. Mating studies, toxicity and reversibility of spermatogenesis following stoppage of treatment were carried out with DNG 40 mg/kg bw at 4-week intervals.

RESULTS

Complete arrest of spermatogenesis was observed after 60 days of treatment at all doses of DNG (20, 30 and 40 mg/kg bw per week)+TU. However, weights of testis and accessory sex organs (epididymis, prostate and seminal vesicle) declined significantly 60 days post treatment compared to vehicle-treated controls. Epididymis in the treated animals was completely devoid of sperm. When the frequency of DNG injection (20 mg/kg bw) was extended to once every 15 days, a few immotile and decapitated sperm were observed in the epididymis. With TU treatment unchanged, animals receiving DNG (40 mg/kg bw) once either every 2- or 4-week intervals demonstrated good and uniform arrest of spermatogenesis. DNG 40 mg/kg per 4 weeks+TU also demonstrated a significant rise in germ cell apoptosis in the seminiferous epithelium. There was no significant increase in the serum high-density lipoprotein and low-density lipoprotein levels at the end of 120 days of treatment. Following withdrawal of treatment after 60 or 120 days, qualitative restoration of spermatogenesis was rapid in the former compared to the latter.

CONCLUSION

Dienogest plus TU has the potential for development as a monthly injectable showing reversible hormonal male contraception with good efficacy.

Male hormonal contraception: a double-blind, placebo-controlled study

BACKGROUND

This study was performed to assess spermatogenesis suppression and safety of a new combination of an etonogestrel (ENG) implant combined with testosterone undecanoate (TU) injections for male contraception. This is the first large placebo-controlled study for male hormonal contraception.

DESIGN AND STUDY SUBJECTS

In this double-blind, multicenter study, we randomly assigned 354 healthy men to receive either a low- or high-release ENG implant sc combined with im TU injections (750 mg every 10 or 12 wk or 1000 mg every 12 wk) or placebo implant and injections. Treatment duration was 42 or 44 wk and posttreatment follow-up at least 24 wk.

RESULTS

Overall, spermatogenesis was suppressed to 1 million/ml or less at wk 16 in 89% of men, with approximately 94% in two high-release ENG groups. Suppression was maintained up to the end of the treatment period in 91% of men. For all men who completed the treatment period, 3% never achieved 1 million/ml or less. Median recovery time to a sperm concentration above 20 million/ml was 15 wk (mean 17 wk, 95% confidence interval 16-18 wk). Treatment was well tolerated. As compared with the placebo group, more men in the active treatment groups reported adverse events such as weight gain, mood changes, acne, sweating, or libido change. For both spermatogenesis suppression and safety, differences were small between the active treatment groups.

CONCLUSIONS

The combination of an ENG implant with TU injections is a well-tolerated male hormonal method, providing effective and reversible suppression of spermatogenesis. Although the results are good, there is still room for improvement, possibly by adjusting the dose regimen or changing the mode of application.

Determinants of the rate and extent of spermatogenic suppression during hormonal male contraception: an integrated analysis

CONTEXT

Male hormonal contraceptive methods require effective suppression of sperm output.

OBJECTIVE

The objective of the study was to define the covariables that influence the rate and extent of suppression of spermatogenesis to a level shown in previous World Health Organization-sponsored studies to be sufficient for contraceptive purposes (< or =1 million/ml).

DESIGN

This was an integrated analysis of all published male hormonal contraceptive studies of at least 3 months' treatment duration.

SETTING

Deidentified individual subject data were provided by investigators of 30 studies published between 1990 and 2006.

PARTICIPANTS

A total of 1756 healthy men (by physical, blood, and semen exam) aged 18-51 yr of predominantly Caucasian (two thirds) or Asian (one third) descent were studied. This represents about 85% of all the published data.

INTERVENTION(S)

Men were treated with different preparations of testosterone, with or without various progestins.

MAIN OUTCOME MEASURE

Semen analysis was the main measure.

RESULTS

Progestin coadministration increased both the rate and extent of suppression. Caucasian men suppressed sperm output faster initially but ultimately to a less complete extent than did non-Caucasians. Younger age and lower initial blood testosterone or sperm concentration were also associated with faster suppression, but the independent effect sizes for age and baseline testicular function were relatively small.

CONCLUSION

Male hormonal contraceptives can be practically applied to a wide range of men but require coadministration of an androgen with a second agent (i.e. progestin) for earlier and more complete suppression of sperm output. Whereas considerable progress has been made toward defining clinically effective combinations, further optimization of androgen-progestin treatment regimens is still required.

Pharmacokinetics and pharmacodynamics of oral testosterone enanthate plus dutasteride for 4 weeks in normal men: implications for male hormonal contraception

Oral administration of testosterone enanthate (TE) and dutasteride increases serum testosterone and might be useful for male hormonal contraception. To ascertain the contraceptive potential of oral TE and dutasteride by determining the degree of gonadotropin suppression mediated by 4 weeks of oral TE plus dutasteride, 20 healthy young men were randomly assigned to 4 weeks of either 400 mg oral TE twice daily or 800 mg oral TE once daily in a double-blinded, controlled fashion at a single site. All men received 0.5 mg dutasteride daily. Blood for measurement of serum luteinizing hormone (LH), follicle-stimulating hormone (FSH), testosterone, dihydrotesterone (DHT), and estradiol was obtained prior to treatment, weekly during treatment, and 1, 2, 4, 8, 12, 13, 14, 16, 20, and 24 hours after the morning dose on the last day of treatment. FSH was significantly suppressed throughout treatment with 800 mg TE once daily and after 4 weeks of treatment with 400 mg TE twice daily. LH was significantly suppressed after 2 weeks of treatment with 800 mg TE, but not with 400 mg TE. Serum DHT was suppressed and serum estradiol increased during treatment in both groups. High-density lipoprotein cholesterol was suppresed during treatment, but liver function tests, hematocrit, creatinine, mood, and sexual function were unaffected. The administration of 800 mg oral TE daily combined with dutasteride for 28 days significantly suppresses gonadotropins without untoward side effects and might have utility as part of a male hormonal contraceptive regimen.

Trends in non-medical use of anabolic steroids by U.S. college students: results from four national surveys

This study assessed the prevalence, trends, and student- and college-level characteristics associated with the non-medical use of anabolic steroids (NMAS) among U.S. college students. Data were collected through self-administered mail surveys, from 15,282, 14,428, 13,953, and 10,904 randomly selected college students at the same 119 nationally representative colleges in 1993, 1997, 1999 and 2001, respectively. The prevalence of lifetime, past-year and past-month NMAS was 1% or less and generally did not change significantly between 1993 and 2001, with one exception: past-year NMAS increased significantly among men from 1993 (0.36%) to 2001 (0.90%). Multiple logistic regression analyses revealed that lifetime and past-year NMAS were associated with student-level characteristics such as being male and participation in intercollegiate athletics. Lifetime and past-year NMAS were also positively associated with several risky behaviors, including cigarette smoking, illicit drug use, drinking and driving, and DSM-IV alcohol use disorders. Nearly 7 out of every 10 lifetime non-medical users of anabolic steroids met past-year criteria for a DSM-IV alcohol use disorder. Although the overall prevalence of NMAS remained low between 1993 and 2001, findings suggest that continued monitoring is necessary because male student-athletes are at heightened risk for NMAS and this behavior is associated with a wide range of risky health behaviors. The characteristics associated with NMAS have important implications for future practice and research.

The relative roles of follicle-stimulating hormone and luteinizing hormone in maintaining spermatogonial maturation and spermiation in normal men

CONTEXT

Male hormonal contraception via gonadotropin and intratesticular androgen withdrawal disrupts spermatogenesis at two principal sites: 1) spermatogonial maturation, and 2) spermiation.

OBJECTIVE

The objective of this study was to explore the relative dependence of each stage of germ cell development on FSH and LH/intratesticular androgen action.

DESIGN, SETTING, AND PARTICIPANTS

Eighteen men enrolled in this prospective, randomized 14-wk study at Prince Henry's Institute.

INTERVENTIONS

Subjects (n = 6/group) were assigned to 6 wk of 1) testosterone (T) implant (4 x 200 mg sc once)+depot medroxy progesterone acetate (DMPA; 150 mg im once); 2) T implant+DMPA+FSH (300 IU sc twice weekly); and 3) T implant+DMPA+human chorionic gonadotropin (hCG; 1000 IU sc twice weekly as an LH substitute). Men then underwent a vasectomy and testicular biopsy with previously reported control data used for comparison.

MAIN OUTCOME MEASURES

Germ cell number (assessed by the optical disector stereological approach) and intratesticular androgen levels were determined.

RESULTS

T+DMPA alone significantly suppressed type B spermatogonia, preleptotene through to pachytene spermatocytes, and round spermatids from control (P < 0.05). All germ cell subtypes were maintained at control levels by either FSH or LH activity, except pachytene spermatocytes, which were found to be lower in the hCG vs. FSH (P < 0.01) and control groups (P < 0.05).

CONCLUSIONS

FSH and LH maintained spermatogenesis independently in this gonadotropin-suppressed model. Compared with LH, FSH showed better maintenance of pachytene spermatocyte number, whereas improved conversion to round spermatids was suggested with hCG treatment. Future contraceptive treatment strategies must consider independent regulation of spermatogenesis by both FSH and LH/intratesticular androgens for maximum efficacy.