[Interstitial endocrine apparatus of testes of experimental animals in conditions of chromium-benzene intoxication].

With the use of histological, morphometric and statistical methods there was shown a gonadotropic effect of chromium, benzene and also their mixtures in male mice (CBA x C57Bl6) F1. The established structural changes in the testes of exposed animals showed the suppression of their germinative and endocrine functions. The response of Leydig cells in the chromium group expresses a development of the compensatory process in the relation with the destruction of seminiferous epithelium.

[Combined effects of aluminium and immobilization stress on the reproductive system of male rats].

The evaluation of the isolated and combined effects of aluminum and immobilization stress on the reproductive system of male laboratory rats has been performed. We have established the influence of these factors on spermatogenesis and spermiogenesis: the development of degenerative processes in the testes, on specific hormonal status, apoptosis, increasing abnormal forms of epididymal sperms and reducing their mobility, and on the growth of early embryonic losses. Neither synergistic nor antagonistic effect in the combined aluminum and the stress action has been found.

Adjudin targeting rabbit germ cell adhesion as a male contraceptive: a pharmacokinetics study.

Adjudin (1-(2,4-dichlorobenzyl)-1H-indazole-3-carbohydrazide; formerly called AF-2364) has been shown to inhibit spermatogenesis by disrupting anchoring junctions at the Sertoligerm cell interface. This, in turn, leads to germ cell loss from the seminiferous epithelium, and transient infertility. Adjudin's efficacyin inhibiting spermatogenesis, the recovery of spermatogenesis after cessation of the drug, and side effects were examined in adult male Japanese rabbits. The pharmacokinetics profiles of adjudin in rabbits after oral administration and after intravenous injection were compared. Rabbits received 25 mg/kg adjudin once weekly for 4 consecutive weeks either by intravenous injection or by gavage. Vehicle-treated rabbits were used as controls. At 1, 2, 3, 4, and 8 weeks after treatment, testes were removed for microscopic examination to assess the status of spermatogenesis. Four weeks after intravenous cessation of adjudin, the recovery of spermatogenesis also was monitored. Blood was withdrawn after first administration to measure plasma concentrations of adjudin by high-performance liquid chromatography. Four weeks after intravenous treatment, examination of testis sections showed rapid exfoliation of elongated/elongating spermatids and the presence of large multinucleated cells; more than 95% of germ cells were absent from the seminiferous epithelium. Intravenous treatment showed a more severe disturbance of spermatogenesis compared with gavage treatment, which was correlated with bioavailability of the drug. The areas under the curve for intravenous injection and gavage were 20.11 +/- 1.90 and 2.23 +/- 0.45 mg x h x L(-1), respectively. These results illustrate the potential of adjudin as a male contraceptive, and the efficacy is associated with the bioavailability of the drug.

A novel potent indazole carboxylic acid derivative blocks spermatogenesis and is contraceptive in rats after a single oral dose.

Women have historically been the focus for development of new contraceptive methods. The National Institutes of Health, World Health Organization, and Institute of Medicine have stressed the need to develop nonhormonal, nonsteroidal male contraceptive agents. We report results from initial dose-ranging studies of a new indazole carboxylic acid analogue, gamendazole. An infertility rate of 100% was achieved in seven out of seven proven-fertile male rats 3 wk after a single oral dose of 6 mg/kg of gamendazole. Fertility returned by 9 wk in four of seven animals, with typical numbers of normal-appearing conceptuses. A fertility rate of 100% returned in four of six animals that became infertile at a single oral dose of 3 mg/kg of gamendazole. No differences in mating behavior were observed in either of the gamendazole-treated groups versus the control (vehicle-only) group. In the animals that showed reversible infertility, a transient increase in circulating FSH levels coincided with an initial decline in inhibin B levels after administration of gamendazole, but no other significant changes in circulating reproductive hormones were observed. Gamendazole inhibited production of inhibin B by primary Sertoli cells in vitro with a median inhibitory concentration of 6.8 thorn+/- 3.0 (SEM) (3/4)x 10(-10) M, suggesting that Sertoli cells are a primary target. A biotinylated gamendazole analogue revealed cytoplasmic and perinuclear binding of gamendazole in primary Sertoli cells. Gamendazole represents the most potent new oral antispermatogenic indazole carboxylic acid to date. Our results, however, demonstrate that additional dose-finding studies are required to improve reversibility and widen the therapeutic window before more detailed drug development of this potential nonhormonal male contraceptive agent can occur.

Teratogenic effects of bis-diamine on early embryonic rat heart: an in vitro study.

BACKGROUND: Bis-diamine induces cardiac defects, including conotruncal anomalies in rat embryos when the agent is administered to the mother. To evaluate the teratogenic effects and mechanism of bis-diamine, we performed morphological and immunohistochemical analyses of early rat embryos cultured in medium containing bis-diamine. METHODS: The embryos were removed from mother rats on gestational day 10.5 and cultured in medium containing 1 mg of bis-diamine for 6 hr. The embryos were then cultured in medium only for another 6, 12, 18, and 42 hr, corresponding to embryonic day (ED) 11.0, 11.25, 11.5, and 12.5, respectively. Some embryos from the same mothers were used as controls and were cultured in medium only for the corresponding periods to the embryos exposed to bis-diamine. Some mother rats were given a single oral dose of 200 mg of bis-diamine on gestational day 10.5. Embryos from these pregnant rats were removed 6 hr after the oral administration of bis-diamine, and were also cultured in medium only for 6, 12, 18, and 42 hr. RESULTS: No cardiac abnormalities were detected in the controls at any stage of development. Thirty-three of 51 (65%) embryos exposed to bis-diamine and 15 of 20 (75%) embryos removed from bis-diamine-administered mothers showed abnormal cardiac development, including dilated ventricle, elongation of outflow tract, and pericardial defect on ED 11.5. Four of six (67%) embryos exposed to bis-diamine, and five of seven (71%) removed from bis-diamine-administered mothers also presented almost the same cardiac abnormalities on ED 12.5. No cardiac abnormalities were detected in bis-diamine-treated embryos before ED 11.5. In addition, the expression of neural cell adhesion molecule (N-CAM) was examined using immunohistochemical methods. Fewer N-CAM immunoreactive cells were detected in the third and fourth aortic arches in the bis-diamine-treated embryos than in controls on ED 11.5. However, more N-CAM immunoreactive cells were detected in the bis-diamine-treated embryos than in controls on ED 12.5. CONCLUSIONS: These results suggest that bis-diamine induces cardiac anomalies by delaying the migration of neural crest cells into the heart and by disturbing the proliferation of pericardial precursor during early cardiac development.

Stage-specific DNA synthesis of rat spermatogenesis as an indicator of genotoxic effects of vinblastine, mitomycin C and ionizing radiation on rat spermatogonia and spermatocytes.

We have studied the effects of three known mutagens: vinblastine sulphate, mitomycin C and local irradiation of testes on the stage-specific DNA synthesis in the rat testis by using transillumination assisted microdissection of rat seminiferous tubules. It enables us to investigate the sensitivity of different types of spermatogonia and preleptotene spermatocytes to the genotoxic effects of these agents. According to our results, spermatogonia and preleptotene spermatocytes are quite resistant to the action of vinblastine at the treatment times and the doses used. After treatment with mitomycin C, type A2, A3 and A4 spermatogonia seem to be the first cell types affected, which shows itself as a reduction in the DNA synthesis at stages I, II-III, XIII-XIV of the epithelial cycle two and/or three days after the treatment. It also seems that they are mostly affected during the S-phase of their cell cycles. In addition, preleptotene spermatocytes are also sensitive to the action of mitomycin C when they are treated in the G1 phase of the cell cycle. The local irradiation of 3 Gy has severe effects on the spermatogonia of rat testis which can be seen already 18 h after the treatment and becomes more evident 42 and 66 h after the treatment as a reduction of DNA synthesis at stages XII-V. Type A spermatogonia (A1-A4) seem to be the most sensitive cell types to the action of irradiation. This study indicates that the novel method of stage-specific DNA synthesis in rat spermatogenesis allows detailed studies of sensitivities in differentiating spermatogonia to genotoxic agents.

Testicular toxicity of WIN 18446 in the laboratory mouse.

The effect of oral administration of N,N'=bis (dichloroacetyl)-1, 8-octamethylenediamine (WIN 18446) (200 mg/kg body weight/day, up to 30 days) on the testis of the Parkes (P) strain laboratory mouse was studied. The drug caused reduction in testicular weight and severe atrophic changes in the seminiferous tubules. A duration-dependent effect of the drug was observed on the germ cells. The drug had its initial impact on spermatids followed by spermatocytes, ultimately culminating in the Sertoli cell-spermatogonia syndrome. The drug-induced changes included exfoliation of germ cells, formation of multinucleated giant cells, and vacuolization of cytoplasm and displacement (towards the lumina of the tubules) of Sertoli cell nuclei. Even 75 days after drug withdrawal, testicular weight remained depressed and in 15 to 20% of the tubules there was incomplete recovery of spermatogenesis. Our data indicate that WIN 18446 induces sustained impairment of spermatogenesis by a direct action on spermatogonia or indirectly by affecting the integrity of the Sertoli cells. The Leydig cells remained unaffected in WIN 18446-treated mice.

Teratogenic action of bis(dichloroacetyl)diamine on rats: patterns of malformations produced in high incidence at time-limited periods of development.

Win 18,446, a bis(dichloroacetyl)diamine, is a drug that was previously shown to suppress spermatogenesis and to be an effective oral abortifacient in rats. The present study shows that the drug is capable of producing characteristic congenital malformations in high incidence, by a single treatment, and with high survival of fetuses to day 21. Gestation day 11 is the most sensitive time. The teratologies obtained after various schedules of treatment include malformations of the snout (100%), septal heart defects (100%) diaphragmatic hernias (100%), cryptorchism (100%), cervical pockets (100%) and absent or small irregular thymus (92%). Some of these data, namely of the heart, face and thymus, cluster in patterns that indicate that the action of the drug is upon a time-resistricted developmental process. These periods of sensitivity are subsiding or have ended before primordia of these structures appear, but they coincide with the proliferation and migration of those mesenchyme cells that will eventually form or contribute to the structures affected. It is postulated that the drug acts on these mesenchyme cells, or on the extracellular matrix that provides the necessary framework for their dispersal.