Complete Suppression Of Spermatogenesis Research Articles

Pathological Study of the Thyroidectomy on Testes of Rabbit

The current study was conducted on fifteen adult male rabbits (2-3 kg), divided into 3 equal groups (control group, group A ‘seven days’ & group B ‘fourteen days group’), removing of the testes and thyroidectomy have been made to both A and B groups. Results indicated that several clear histopathological changes have been observed in the testicular tissues including, complete suppression of spermatogenesis with vacuolar degeneration of epithelial lining of seminiferous tubules in both groups. Moreover, a multinucleated giant cell spermatid in the lumen of seminiferous tubules was featured with no sperm was detected in the lumen of group B. It has been concluded, that the thyroidectomy can cause serious effects on male sexual organs due to diminishing of sex hormones responsible to it growth.

Suppression of sexual activity and reproduction in male small ruminants

Handling and husbandry of male small ruminants after sexual maturity often become difficult. Castration is currently the most reliable solution to this problem. Medicinal procedures for temporary inhibition of the gonad function could provide an alternative. Following a short overview of surgical castration, the current knowledge on the application of vaccines against gonadotropin-releasing hormone (GnRH) and GnRH agonist in rams and billy goats is presented in a literature overview. In rams, GnRH vaccination has been used successfully for temporary suppression of the reproduction function, regardless of an animal's age at the time of therapy initiation. Fewer investigations are available for the billy goat. A complete suppression of spermatogenesis was not achieved in all cases. Currently, treatment with GnRH agonists does not represent a relible method for the suppression of gonad function.

Castration of Iraqi local bucks by bilateral spermatic cord torsion compared with double ligation of spermatic cord

This study aimed to investigate the efficacy of using spermatic cord torsion as one of the easy castration techniques in Iraqi local black goat, and compared with double ligation of the spermatic cord also to be acquainted if the age of animals has an effect on spermatic cord torsion technique. This present study was done in the animals farm of the college of the veterinary medicine of Al-Qadissiya university, 30 local male blackbucks (15 kids of 2.5 - 3 months) (15 adult bucks of 13 - 15 months) with body weight (13.4 ± 2.21) and (31.9 ± 3.25) Kg respectively, were supplied for two symmetrical experiments, each one included division the animals randomly to three groups, first group (G1) left as control , Second group (G2) had spermatic cord ligation of both testes and third group (G3) had bilateral spermatic cord torsion and after two months orchiectomy of all tests were done to study the dimensions, the weight, histopathology of the testes and the level of serum testosterone hormone. The results revealed that the castration lead significance (P<0.01) to increase the body weight of both kids and bucks as compared with control, the maximum weight gained was in the bilateral spermatic cord torsion, while in the kids was the ligation group. Weights, lengths, and circumferences of both testes of all animals showed a significant decrease (P<0.01) as compared with control animals. Testosterone hormone analysis revealed a significant decrease (P<0.01) in its level in all castrated groups when compared with control group. Seminal analysis showed a significant decrease (P<0.01) (seminal plasma only) for the volume, concentration, viability, individual and mass motility of the sperms of the all castrated animals as compared with control. The histopathological study of all treated testes corroborated there were a severe degeneration and fibrosis in the testicular tissue as well as in the Sertoli and Leydig cells and complete suppression of spermatogenesis in all treated groups. The conclusion that spermatic cord torsion caused damage to the testes as ligation did with no effect of age of animals on this technique.

40% of men up for ‘the pill’

In a nation-wide survey commissioned by the UK's Science Museum, four out of ten men aged 18–45 said they would be likely to take the male contraceptive pill. Recent trials of the pill – oral progestagen (desogestrel) combined with a subcutaneous source of testosterone to maintain libido – resulted in the complete suppression of spermatogenesis. The effects of the treatment were reversible. However, despite the promise of a new contraceptive option for men, those included in the survey expressed concerns about potential side-effects, and 56% of interviewees said that the risk of unforeseen long-term health problems would put them off the pill. Richard Anderson, who is leading trials of the male pill at Edinburgh University, agreed that the long-term effects of the male pill are unknown, but added that ‘the benefits of pregnancy-free sex are real and immediate’. If the trials are successful, the pill, produced by Organon, could be available in 2005. RC

Testicular heat exposure enhances the suppression of spermatogenesis by testosterone in rats: the "two-hit" approach to male contraceptive development.

The objectives of the study were to determine stage-specific changes in the kinetics of germ cell apoptosis induced by administration of exogenous testosterone (T) alone and to examine whether addition of a single testicular heat exposure would enhance the induction of germ cell apoptosis and the suppression of spermatogenesis by T. Adult male rats were implanted with 3-cm SILASTIC brand capsules (Dow Corning Corp.) containing T for up to 6 weeks. Intratesticular T levels declined to 2.9% of control values by 1 week and remained suppressed at 2, 3, and 6 weeks after T administration. The incidence of germ cell apoptosis (expressed as numbers per 100 Sertoli cells) was low in control rats (0-9.52). After T treatment, the mean incidence of apoptosis at stages VII-VIII increased significantly by 1 week (21.43 +/-3.33) and showed further increases by 6 weeks (56.30 +/- 7.47); apoptotic rates remained low at early (I-VI) and later (XII-XIV) stages. To test whether the combination of T with a single testicular heat exposure resulted in more complete suppression of spermatogenesis than either treatment alone, four groups of adult rats received one of the following treatments: 1) a subdermal empty polydimethylsilozane implant, 2) exposure to a single testicular heating (43 C for 15 min) applied on day 14, 3) 3-cm T implant, or 4) 3-cm T implant and a single testicular heat exposure (applied on day 14). All animals were killed at the end of 6 weeks. In the heat-treated group, testis weight and testicular sperm counts were decreased to 65.4% and 28.9% of control levels, respectively. The corresponding values in the T-treated group were 49.7% and 24.9% of control levels, respectively. Notably, addition of heat to T further reduced testis weight to 31.1% of control levels and testicular sperm counts to near zero. Histomorphometric analysis showed that all treatments reduced seminiferous tubular diameter and epithelial and luminal volume, with the greatest decrease after combined T and heat treatment. Heat exposure in animals bearing T implants markedly reduced the number of pachytene spermatocytes and round spermatids through apoptosis, resulting in tubules devoid of mature spermatids. Spermatogonia and preleptotene spermatocytes remained unaffected. These results clearly demonstrate that 1) exogenous T reduces intratesticular T and induces apoptosis mainly at stages VII-VIII within 1-6 weeks; 2) the combined treatment of T and heat markedly inhibits spermatogenesis, resulting in near azoospermia within 6 weeks; and 3) meiosis and spermiogenesis are the most vulnerable phases of spermatogenesis in response to T plus heat treatment. These findings suggest that a combination of hormonal treatment such as T and a physical agent (heat exposure) is more effective in suppressing spermatogenesis than either treatment alone. We hypothesize that combination of two antispermatogenic agents ("two hit") working at separate stages of the spermatogenic cycle will lead to greater male contraceptive efficacy.

Investigation into suitable carrier molecules for use in an anti-gonadotrophin releasing hormone vaccine

Gonadal function can be controlled through immunoneutralisation of gonadotrophin releasing hormone (GnRH), with an analogue, GnRH-glycys, linked to a carrier molecule and an appropriate adjuvant. In this study, four different types of carrier molecule were investigated: (a) single and branched amino acid polymers — [poly-( d-glu, d-lys) and poly-(phe, glu)-poly( dl-ala)-poly(lys)]; (b) bacterial toxoids — diphtheria (DT) and tetanus (TT); (c) synthetic T-helper epitopes — derived from malarial circumsporozite protein (CS) and measles virus fusion protein (MVF); and (d) thyroglobulin (Thy) — a large protein. The effect of non-ionic surfactant vesicles (NISV) and an aluminum hydroxide based adjuvant (alum), was also examined. Although good antibody responses were achieved with GnRH-glycys-DT, GnRH-glycys-TT and GnRH-glycys-Thy, adsorbed onto alum and the dimerised synthetic T-helper epitope constructs, incorporated into NISV, a critical antibody titre was necessary to result in morphological changes in the gonads and complete suppression of spermatogenesis. This was only achieved with tetanus toxoid and the dimerised T-helper epitopes.

Counteractive effects of agonistic and antagonistic gonadotropinreleasing hormone analogs on spermatogenesis: sites of action

Both gonadotropin-releasing hormone (GnRH) agonistic and antagonistic analogs have been shown to inhibit reproductive hormonal function. While predictable and complete suppression of spermatogenesis is the ultimate goal of a number of clinical studies aimed at developing male contraceptive agents based on GnRH analogs, neither class of analog has been shown to completely inhibit spermatogenesis in man. The potential for a synergistic interaction of submaximal doses of these two classes of GnRH analogs was investigated in the present studies. In these studies 200 ng/day of a potent agonist (D-Leu6des-Gly10GnRH ethylamide) and 100 micrograms/day of a potent antagonist (NAc-L-Ala1, pCl-D-Phe2, D-Trp3,6GnRH) were administered subcutaneously, both alone and in combination, to adult male rats for 21 days. Serum gonadotropins and testosterone, pituitary GnRH receptor content, gonadal gonadotropin receptors, and intratesticular sperm counts were quantitated in each treatment group. Despite the ability of both GnRH agonists and antagonists to inhibit reproductive function when administered as single agents in this study, combined treatment with the two classes of GnRH analogs was less effective than either agent alone at these doses in the pharmacologic suppression of spermatogenesis.

Trial of high-dose testosterone undecanoate in treatment of male infertility.

The effectiveness of high-dose testosterone undecanoate administered orally in suppressing spermatogenesis and eliciting the rebound-phenomenon was investigated in an uncontrolled clinical trial. Five men with fertility disturbances were treated for 10--12 weeks with 3 x 80 mg testosterone undecanoate daily. One patient achieved azoospermia and 2 oligospermia below 10 mill/ml, 1 suppressed to 27 mill/ml and 1 patient showed no effect. After cessation of treatment, 3 patients showed an increase in sperm concentration to greater than 50% of control values, one showed an increase of 35% and one showed a decrease in sperm count. The preliminary data suggest that although complete suppression of spermatogenesis is not uniformly achieved, a controlled study on the effects of high doses of testosterone undecanoate in male infertility may now by warranted.