Hormonal effects of GnRH agonist in the human male: II. Testosterone enhances gonadotrophin suppression induced by GnRH agonist

Contraception across transgender

Sexual and reproductive issues are essential elements of well-being in cisgenders as well as for the transgender population. Gender-affirming hormonal treatments (GAHTs) aim to induce phenotypical changes congruent with the desired gender and subsequent reduction of gender dysphoria. While genital surgical procedures including hysterectomy and/or adenectomy cause permanent loss of ability to conceive, GAHT may induce a varying degree of reversible loss of fertility. For these reasons, transgender men and women need to be counseled concerning contraceptive options and potential effects of treatment on reproductive function before initiating GAHT. The literature reports that sexual activity with genital involvement is performed by less than half of transgender persons who have been sexually active with a partner in the past. Testosterone (T) is the most commonly used compound in transmen and usually leads to amenorrhea within 1-12 months from first administration, however cessation of menses does not mean anovulation. Some studies report cases of unintended pregnancies among transgender men under masculinizing therapy, therefore T treatment cannot be considered a contraceptive option. Currently available contraceptive options have pros and cons in transmen and scarce literature exists on their use. The effects of GAHT on fertility in transwomen are even less well known. Prolonged estrogen exposure induces sperm suppression and morphological changes of the spermatozoa, however the degree of resulting pregnancy protection is unclear. Further research to inform the contraceptive counseling in this population is mandatory.

Continuing the search for a hormonal male contraceptive

This chapter discusses the mechanisms of action of hormonal male contraception, which suppresses the hypothalamic-pituitary-testis axis. When the intratesticular concentration of testosterone is subsequently suppressed to adequately low concentrations, spermatogenesis is arrested. Androgens are a necessary hormonal male contraceptive component because they not only suppress the hypothalamic-pituitary-testis axis, but also provide the male hormone necessary to maintain peripheral androgen functions. Past studies using testosterone alone and testosterone combined with progestins demonstrated contraceptive efficacy in the female partner at rates similar to combined hormonal female methods. Newer hormonal male contraceptive formulations and the alternative routes of administration are discussed, along with potential barriers, challenges, and opportunities for hormonal male contraceptive development. Novel methods that are safe, effective, reversible, user-friendly, and coitus-independent are intrinsic to equitably meet the various needs and limitations of an increasingly diverse population.

Male hormonal contraception

Male hormonal contraception, based on the suppression of both gonadotropins, follicle-stimulating hormone and luteinizing hormone, resulting in marked decrease in sperm production, is designed for couples in stable relationships where the male partner desires to assume family planning responsibilities using reversible methods. Two large scale, multicenter studies that used testosterone injections as the prototype male hormonal contraceptive demonstrated when azoospermia and/or very severe oligozoospermia were attained, contraceptive efficacy was equivalent to female hormonal methods. Current studies aim to find the androgen alone or androgen plus progestin preparations that are most efficacious, user friendly, and with least potential adverse effects. It is likely that injections or implants of androgens either alone or with progestins will become the first male hormonal contraceptive available within this decade. Further research and development include the use of selective androgen and/or progestin receptor modulators, nonpeptide GnRH antagonists, and agents with local actions on the testis for male contraception.

Male contraception

Currently approved male-directed contraceptive methods include condoms and vas occlusion. Vas occlusion is very effective but is intended to be non-reversible. Condoms have a relatively high failure rate, at least partially due to compliance problems and are not accepted by many couples. The only other male-oriented methods in clinical trials utilize the administration of testosterone alone or its combination with another gonadotropin-suppressing agent such as a progestin or a gonadotropin-releasing hormone antagonist. Studies published in the 1990s demonstrated that a testosterone-containing hormonal contraceptive method suppressed spermatogenesis to azoospermia in most men and severe oligozoospermia in the remaining. The contraceptive efficacy after treatment with testosterone alone was comparable to that of female hormonal methods. Having proven that reversible male contraception is a reality, present trials are attempting to identify the best androgen delivery system and the most effective androgen plus progestin preparation. It is likely that the first marketed male hormonal contraceptive method will be a long-acting (injectable or implant) combination of an androgen plus a progestin. Research is continuing to identify other target areas for male contraceptive development, including agents with post-testicular and epididymal sites of action.

Experience with a potent LH-RH agonist, buserelin, alone and in combination with testosterone for antispermatogenic activity, reversibility and toxicity in langur monkey

Chronic intermittent treatment of LH-RH superagonist Buserelin alone or in combination with testosterone enanthate were given to adult male langurs for 90 days to evaluate antispermatogenic activity of alone and combination therapy, maintenance of normal androgenicity, possible toxic effects of agonist treatment, related side effects of testosterone supplementation and complete reversibility of the procedure. A gradual decrease in sperm count was recorded in both treatment groups, along with reduced motility and vitality of the spermatozoa. In the combination group, oligospermia was achieved in 4 out of 5 animals, whereas, only 2 animals became oligospermic in the agonist alone group. Significant decrease in serum testosterone levels along with impaired libido and other testosterone withdrawal symptoms were observed in the Buserelin alone group, conversely normal testosterone levels and libido were observed in the combination group. An elevation in haematological variables and serum total protein concomitant with a slight gain in body weight of the animals were recorded in the combination group; these changes were not encountered in the agonist alone group. Reversibility of all the altered parameters to control range was observed in both treatment groups following 75 to 90 days of treatment withdrawal.

Heterogeneity of sperm density profiles following 16-week therapy with continuous infusion of high-dose LHRH analog plus testosterone

LHRH agonist analogs have been investigated as potential male contraceptives. It has been shown that the LHRH agonistic analog [D-Trp6,Pro9-NEt] LHRH (LHRHA) given to men in single doses up to 500 micrograms daily for up to 20 weeks with the coadministration of testosterone enanthate produces reversible oligozoospermia. Individual responses to the treatment, however, were variable. In this study, we gave the same analog to eight normal male volunteers as a continuous infusion of 500 micrograms daily for 16 weeks. Testosterone enanthate, 100 mg, was given by injection every second week. Six of the subjects became oligozoospermic but the other two retained sperm counts that were greater than 20 million/ml, although their treatment continued for 20 weeks. The reasons for this variability of response are not clear. Serum immunoreactive LH values increased during the infusion period whereas testosterone declined. FSH values fell during treatment in all subjects except the two non-responders. The acute pituitary response to LHRHA during the treatment or shortly thereafter (48 h) was completely abolished, and bioactive LH values were suppressed totally. FSH, LH, testosterone and sperm counts returned to normal in all subjects following discontinuation of LHRHA infusion. Continuous infusion of 500 micrograms of LHRHA daily for 16 weeks with 100 mg of testosterone enanthate every 2 weeks induced desensitization of the pituitary, loss of LH bioactivity, and decreases of FSH and testosterone. This mode of administration, however, did not improve sperm density results obtained earlier by single daily injections of the analog. Heterogeneity of sperm density profiles still persists for reasons that are not yet clear.

Hormonal effects of GnRH agonist in the human male: an approach to male contraception using combined androgen and GnRH agonist treatment

Observations that hypophysectomized men demonstrate predictable azoospermia have led to attempts to suppress gonadotropin secretion with drugs for contraceptive purposes. Testosterone enanthate, given on a weekly or bimonthly basis, failed to predictably induce azoospermia in men. Treatment with agonist analogs of GnRH significantly suppressed spermatogenesis, but led to concomitant decline in serum testosterone concentrations. To prevent GnRH agonist induced changes in libido and potency we tested regimens employing daily subcutaneous injections of 200 micrograms of D(Nal2)6GnRH in combination with 200 mg testosterone enanthate every 2 weeks. This regiment led to 86% decline in mean sperm count over the 16-week treatment period, but azoospermia was not achieved in any subject. Basal or 24 h integrated serum LH or 24 h urinary LH concentrations were not significantly suppressed by combined treatment. In order to assess whether constant infusion of GnRH agonist will lead to greater suppression of gonadal function than its intermittent administration, we administered either 20 or 200 micrograms of D(Nal2)6GnRH to 2 groups of normal male volunteers for 28 days either by single daily injection or by constant subcutaneous infusion. Serum testosterone, LH and FSH responses were not significantly different between the two modes of agonist delivery either at 20 or 200 micrograms dose. Marked decrease in serum testosterone and sperm counts in these studies occurred in the face of little or no change in immunoreactive LH, indicating that the antigonadal actions of GnRH agonist in the human male cannot be fully explained on the basis of downregulation of pituitary LH secretion alone. GnRH agonist treatment however, led to marked decrease in bioassayable LH concentrations suggesting secretion of a molecularly altered LH species with diminished biologic activity.

Inhibition of testicular androgen biosynthesis by chronic administration of a potent LHRH agonist in adult men

The antireproductive properties of LHRH and its agonists have now been clearly established. Using various dosing regimens and routes of administration in animal experiments and in clinical trials, these peptides invariably produce paradoxical inhibitory effects on reproductive function. This ability led to the concept that gonadal steroid-dependent (responsive) tumors might also be affected in a manner analogous to that produced by gonadectomy or by antiandrogenic or antiestrogenic drugs. Numerous data have now appeared in the medical literature on the potential efficacy of the LHRH agonists as a tumor therapy. Using different agonists (D-Ser6, D-Leu6 and D-Trp6-LHRH) and various dosages, the investigators were successful in inducing a "medical castration" with androgen levels comparable to castrate control subjects. Objective tumor regression and significant clinical improvement paralleled the hormonal suppression shown in our studies and by other groups. Another interesting potential clinical application of the ability of LHRH agonist to inhibit testicular function is its development as a male contraceptive. This approach is being tested by a few groups. In order to preserve potency, exogenous androgens must be administered with the agonist. Long-term pituitary suppression in boys with idiopathic precocious puberty has now been achieved and premature sexual development suppressed. In man the main mechanism responsible for testicular inhibition seems to be the achievement of a temporary and reversible state of hypogonadotropic hypogonadism. Recent data show that LHRH agonist alters the ratio of bioactive and immunoreactive LH and suggest a direct effect on LH biosynthesis as a mechanism of action of LHRH agonist analogs. Other findings support the lack of direct effect of LHRH agonist on Leydig cells in humans. In view of the main potential clinical applications--as therapy for chronic hormone-dependent disease or as a male contraception--major new developments are being undertaken in the way of administration of these substances by slow delivery systems.