Adriamycin (ADR), an anticancer drug, was intravenously administered to Slc : SD male rats at doses of 0, 1 and 2 mg/kg once a week for 4 or 9 weeks before pairing, and the treatment period and parameters suitable for detection of male fertility disorder were examined. No adverse effects were observed on the copulation index, fertility index and spermatozoa, but testicular weights were low in the 1 and 2 mg/kg groups after 4-week treatment. In the 2 mg/kg group after 9-week treatment, 11 of 12 males had died or became moribund, and no successful pregnancies were observed. The males in the 1 and 2 mg/kg groups after 9-week treatment had decreased weights of the genital organs, an extremely decreased number of sperm and low sperm motility as well as a low implantation rate and a decreased number of live fetuses. Microscopically, the numbers of spermatogonia were decreased in the 1 and 2 mg/kg groups after 4-week treatment, whereas the numbers of even spermatozoa were diminished and genital organs showed atrophy after 9-week treatment. These results indicate that 4-week treatment before pairing is sufficient to detect effects of ADR on the testis, especially on spermatogonia, and that microscopic findings and testis weight are appropriate parameters for detection of male fertility disorders.

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α-Chlorohydrin (α-CH) was administered orally at doses of 0, 2 or 8 mg/kg/day for 2 weeks to Sprague-Dawley male rats. At the end of the administration period or 2 weeks after withdrawal (one group also treated with 8 mg/kg for 4 weeks), males were mated (treatment with α-CH was continued throughout the mating period of 2 weeks) with untreated females, and underwent examination, including assessment of sperm, to determine fertility. No significant treatment-associated changes were observed in terms of body weight, food consumption, or weights of the testes, epididymides or prostate in either the 2 or the 8 mg/kg group. Although there were no significant differences in sperm number, viability or maturation rate between either of the treated groups and the control group, sperm motility in the 8 mg/kg group observed after 2 hours incubation and sperm activity in groups treated with 8 mg/kg observed immediately after collection or after 2 hours incubation, as well as in the 2 mg/kg observed after 2 hours of incubation were significantly decreased. Two weeks after withdrawal (8 mg/kg group only), sperm motility and activity were no longer decreased. Histopathological examination of the testes after 4 weeks of α-CH administration disclosed no abnormalities on staining with Hematoxylin-Eosin after fixation in Bouin's solution. All treated male rats copulated with untreated females, but no pregnancy resulted from mating in the 8 mg/kg continuous administration case. There were no significant differences between the control and 2 mg/kg groups in numbers of corpora lutea and implantations in animals becoming pregnant. Two weeks after withdrawal, male rats treated with 8 mg/kg copulated and impregnated females. These findings suggest that evaluation of male fertility is possible within or following a 2-week treatment period for compounds like α-CH which have no toxicological, histopathological or sperm morphological effects, and that the use of several parameters for sperm examination is important in determining male fertility.

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To assess the testicular toxicity induced by compound C, a new platinum complex being developed as an anti-cancer drug, the substance was intravenously administered to male rats at doses of 1, 3 and 10 mg/kg/day for 4 weeks and at doses of 0.3, 1 and 3 mg/kg/day for 9 weeks. Males were cohabited with non-treated females after these treatment periods and at sacrifice the genital organ weights and number of sperm in the testis were recorded and a histopathological examination performed. The females were sacrificed on day 13 of gestation and the numbers of corpora lutea, implantations and resorptions were counted. In the 4 weeks treatment 10 mg/kg/day group, the testis weight increased while the weights of the epididymides, seminal vesicles and prostate decreased significantly, and the number of sperm was significantly decreased. Extension of seminiferous tubules, vacuolization of spermatocytes, spermatids and Sertoli cells, and degeneration of spermatocytes and spermatids were observed by histopathological examination. Copulation and impregnation were not affected by treatment but the implantation rate was significantly decreased in the 10 mg/kg/day group. These results show that compound C has testicular toxicity like other platinum complexes and that organ weight, number of sperm, number of implantation and histopathological examination are useful for detection purposes. Treatment with compound C for 9 weeks did not affect male reproductive function in spite of severe general toxicity. This suggests that testicular toxicity should be detected after 4 weeks rather than 9 weeks treatment.

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Results of two toxicity studies of Compound E, which is an anticancer drug, on male reproductive organs and fertility by oral repeated dosing at dose levels of 12.5, 25 and 50 mg/kg/day for 4 and 9 weeks in rats were compared. After repeated dosing, the male fertility was studied by mating with untreated female animals. At the dose of 50 mg/kg/day in the 4-week study, Compound E significantly decreased testes weight and number of epididymal sperm, caused histopathological changes in the testis and epididymis characterized by decreased germ cells, but did not affect fertility. The dose of 25 mg/kg/day in the 9-week study caused reduction in epididymal weight and number of epididymal sperm and histopathological changes in the testis. The dose of 50 mg/kg/day in the 9-week study was lethal and caused more prominent toxic effects in the reproductive organs and loss of fertility. The present studies suggest that the order of sensitivity of parameters on male reproductive organs is as follows ; histopathological examination = organ weight &gt number of sperm in epididymis &gt pregnancy index &gt copulation index. Further, 4-weeks repeated dosing is of sufficient duration to predict adverse effects of test compounds.

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To assess the optimal dosing period and parameters for measurement of effects on male fertility, Compound T was administered to male Jcl : Wistar rats at dosage levels of 0, 2, 10 and/or 50 mg/kg/day for 4 weeks (Experiment 1) or for 9 weeks (Experiment 2). Experiment 1 : In the 50 mg/kg group, the ventral prostate weight was low when compared to the control value, and desquamation of round spermatids was observed in the tested. Experiment 2 : when treated males were mated with untreated females after dosing for 9 weeks (the first mating), the fertility index was slightly lowered and pre-implantation loss was significantly elevated in the 50 mg/kg group as compared to the control values. In this treatment group, serum testosterone level at 2.5 hours after dosing was significantly decreased after dosing for 12 weeks, and degeneration of spermatids/spermatocytes in the testis and epididymis was observed after dosing for 13 weeks. After a recovery period of for 6 weeks, remating resulted in copulatory and fertility indices and cesarean section data which were comparable in all groups. In conclusion, there were no differences in toxicity relevant to male fertility between 4 and 9 weeks of dosing, and it is considered that the observed changes resulted from decreased function of Sertoli cells due to depressed production/secretion of testosterone.

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As part of a collaborative project to determine optimal administration period and parameters to detect compound effects on male fertility in the rat, adult male rats were administered cyclophosphamide daily at 5, 10, 20 and 40 mg/kg for 2 weeks, or at 2.5, 5 and 10 mg/kg for 4 or 9 weeks. After the pre-pairing administration period, each male was paired with an untreated female. After mating, testes and epididymides were removed and examined for organ weights, sperm head counts, sperm morphology and histopathology. Mated females were caesarian-sectioned on Day 13 of gestation. Although atrophy of epithelia in the cauda epididymides and decreases of spermatogenic cells in the testes were observed in the higher dose groups in the 2w study, no other effects on the male reproductive system were noted in any of the studies. There were clear effects on pregnancy outcome ; implantation efficiency was decreased in the highest dosage groups and postimplantation losses increased in all the dosage groups in all studies. These results suggest that a fertility study with females is needed particularly in the case of mutagenic agents, together with a detailed histopathological evaluation for reliable detection of toxicity on the male reproductive system.

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In order to examine the optimal administration period and parameters for male fertility assessment, male rats were subcutaneously administered 0.2, 2 or 20 μg/kg of estradiol benzoate (E₂B), a known testicular toxicant, for 4 weeks or 9 weeks before mating. After 4 weeks administration, suppression of body weight gain and food consumption, decreases in prostate and seminal vesicle weights, atrophy of Leydig cells, and mature spermatid retention at stages IX, X and XI were observed in the 2 and 20 μg/kg groups. In the 20 μg/kg group, decreases in epididymides weight and copulation index were also found but the number of sperm and sperm motility were not affected. In the 0.2 μg/kg group, no changes were noted in any parameters. After 9 weeks administration, decreases in testis weight and the number and motility of sperm were observed in the 20 μg/kg group, in addition to the changes found after 4 weeks administration. These results suggest that detailed histopathological evaluation and determination of accessory sex organ weights are sensitive for evaluating the effects of E₂B on male fertility. Results with the 4-weeks treatment were comparable to those with the 9-weeks treatment in terms of these parameters.

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Parameters of male reproductive toxicity of ethinylestradiol were assessed by conducting a mating test, sperm assay, organ weight determination and histopathological examination. Male Sprague Dawley rats were orally administered 0.1, 0.3, 3 or 10 mg/kg/day ethinylestradiol for 4 weeks prior to mating. Body weight gain and food consumption were suppressed in all treated groups. Reproductive ability of the 3 and 10 mg/kg/day males disappeared. Slightly low copulation indices were observed in the 0.1 and 0.3 mg/kg/day groups, although fertility indices were not affected. Sperm could hardly be found in the epididymis of 3 and 10 mg/kg/day males. Sperm counts were also decreased in the other treated groups, but sperm motility was not affected. Decreased absolute and/or relative weights of testes, epididymides, prostate and seminal vesicles were observed in all treated groups along with testis, epididymis, seminal vesicle and prostate atrophy, and degenerative changes of spermatocytes, spermatids, Sertoli cells and Leydig cells. These results suggest that sperm quantification and histopathological assessment are more appropriate for assessing male reproductive toxicity of ethinylestradiol than performance of copulation and fertility tests.

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The toxicity of Etretinate, a retinoid compound, on the male reproductive system was studied in male rats. The drug was administered for four weeks at the dose levels of 0 (control : Vehicle, Peanut oil), 5 and 25 mg/kg/day. The animals were then allowed to mate, and their male reproductive functions and organs were examined in detail. No significant changes due to toxicity were observed in male reproductive functions and organs in the 5 mg/kg/day group after the 4-week treatment. In contrast, males in the 25 mg/kg/day group showed drug-related changes in their reproductive performance (decrease of mating ability and fertility rate), testosterone blood level, sperm head counts, sperm Viability and number in the caudal epididymis, organ weight and in the histopathology of their reproductive organs (atrophy of seminiferous tubules, necrosis of spermatocytes and spermatids, vacuolation of nuclei of spermatocytes and spermatids). Even though Etretinate belong to the retinoid group of compounds, the changes seen in the 25 mg/kg/day group were almost the same as those observed in Vitamin A-deficient animals. In conclusion, there is a correlation between changes due to toxicity observed for parameters of male fertility and for histopathological evaluation of the testis of rats that receiving high dose, treatment with Etretinate for 4 weeks.

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Haloperidol, a neuroleptic, was orally administered at 0, 3, 10, 30 and 60 mg/kg/day in a 4-week dosing study, and 0, 3, 10 and 30 mg/kg/day in a 9-week dosing study, to Sprague-Dawley male rats which were then sacrificed for histopathological examination or mated with untreated females. The males in the mating groups were continuously treated during the mating period. Sperm positive females were sacrificed on day 20 of gestation. The males in the histopathology groups were sacrificed after 4-or 9-week dosing and their testes were fixed in Bouin's fluid and sections stained with HE or PAS. The mated males were sacrificed and reproductive organ weights were determined. At 3 mg/kg or more, reduced spontaneous motor activity was observed and body weights were lowered. The absolute weight of testes was decreased with 60 mg/kg in the 4-week dosing study, and was decreased with 10 and 30 mg/kg in the 9-week dosing study. However, the relative weight was increased or showed a tendency to increase. In the 4-week dosing study, decrease in the fertility index with 60 mg/kg and increase in pre-implantation loss with 30 mg/kg or more were noted. However, there were no adverse effects on the copulation index in any of the treated groups. The males given 60 mg/kg showed slight changes in the testes (necrosis of pachytene spermatocytes in seminiferous tubules of state VII, exfoliation of round spermatids in the lumina and atrophy of Leydig cells) and seminal vesicles (atrophy of epithelial cells). Atrophy of Leydig cells was also observed at 30 mg/kg in the 4-week dosing study. In the 9-week dosing study, neither male reproductive ability nor histopathological parameters were affected by haloperidol up to 30 mg/kg. From the results detailed above, it may be concluded that 4-weeks dosing before mating is suitable for detection of effects of haloperidol on male reproductive ability, and that histopathological changes together provide an optimal parameter for predicting male reproductive disorders.

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Sprague-Dawley male rats were administered nefiracetam orally at daily doses of 500 and 1500 mg/kg/day for 4 or 9 weeks. Although the copulation index was not affected by nefiracetam treatment, the fertility index was extremely low in the 1500 mg/kg/day group for both treatment periods. This high dose group consistently exhibited decreased testicular weights. Epididymal and prostate weights were also reduced in the 1500 mg/kg/day group after both 4- and 9-week treatments and in the 500 mg/kg/day group after the 9-week treatment. Severe degenerative changes such as degeneration of germ cells, loss of germ cells and atrophy of seminiferous tubules were observed in all fats of the 1500 mg/kg/day groups after both 4 and 9 weeks of treatment. Retention of spermatids in stage IX, X and XI seminiferous tubules was also noted after the 4- and 9-week treatments at 500 mg/kg/day. The testicular sperm head counts were markedly decreased following the 4- and 9-week treatments at 1500 mg/kg/day, and mildly reduced after the 4-weeks treatment at 500 mg/kg/day. From these results it is concluded that histopathological examination and the testicular sperm head count method are highly useful for detecting testicular toxicity and that testicular lesions caused by nefiracetam can be detected after 4 weeks of exposure.

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The main focus of this study is the optimal administration period concerning toxic effects on male fertility in rats. To assess functional and morphological changes induced in the testis by nitrazepam, male rats were administered the drug at doses of 0, 20, 40 or 80 mg/kg during pre-mating periods of 2, 4 or 9 weeks and then the 2 weeks of mating. At the end of the administration period the animals were sacrificed and sperm number, motility, abnormalities and histopathological changes in the testis were examined. Decreases in testis weight, epididymis weight, number of sperm in the testis and sperm motility were observed in the 40 and 80 mg/kg sections of the 2, 4 and 9 week pre-mating treated groups. Mating with untreated females revealed no adverse effects on copulation rate in any group ; however, a remarkable decrease in pregnancy rate was noted in the 80 mg/kg section of the 2, 4 and 9 week treated groups. On histological examination, various degrees of localized necrosis in the seminiferous epithelium and Leydig cell hyperplasia were observed in the testis. No clear changes were observed in the 20 mg/kg section of the 2 week pre-mating administration group, but at the 4 week time point, necrosis of spermatogenic cells began to appear. The primary morphological event was evident in spermatocytes with necrosis of the cytoplasm observed from 4 weeks after administration of nitrazepam, although sperm motility and sperm head counts were unaffected. From these findings, examination of sperm characteristics and histopathological changes in the testis are important parameters for evaluation of drugs inducing testicular damage. We conclude that a 4 week administration period is sufficient to detect effects of nitrazepam on male fertility.

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The present study was designed to elucidate the correlation between findings from reproductive performance testing and those from histopathological examination of the testis and sperm analysis in rats given a benzodiazepine derivative, nitrazepam, for 2 and 4 weeks. The mechanisms of toxicological action of nitrazepam on the male reproductive organs were also investigated. Nitrazepam was given orally to Sprague-Dawley male rats (6-week-old) at a daily dose of 80 mg/kg for 2 weeks or at daily doses of 20, 40 or 80 mg/kg for 4 weeks. Treated males were mated to examine reproductive performance with untreated females after each dosing period, and after 4 and 9 week of recovery periods. Necropsy was performed for histopathological examination of the testis and epididymis and for sperm analysis after each dosing period and the final mating trial (total of 11 weeks recovery). In the findings from reproductive performance testing, significant decrease in the fertility index was observed in the 80 mg/kg group even after 2 weeks dosing and thereafter until 4 weeks recovery, though the mating index did not significantly differ from that of controls through the experiment. In the histopathological examination and sperm analysis, testicular signs of toxicity, decrease in number of sperm heads in the testis and increase in number of sperm with abnormal heads in the seminiferous tubules were noted in the 80 mg/kg group after 2 weeks dosing and in the 40 and 80 mg/kg groups after 4 weeks dosing. Concentrations of plasma testosterone and content of testis testosterone in nitrazepam-treated groups were not significantly different from those of controls. Plasma FSH concentration was significantly elevated in the 80 mg/kg group through the experiment, although significant elevation of plasma LH was observed only after 2 weeks dosing. These results indicate that histopathological examination is the most reliable approach to detect male reproductive adverse effects induced by nitrazepam rather than using parameters from mating trials. The four-week-dosing period is appropriate for their detection. Hypospermatogenesis induced by nitrazepam is suggested to be caused by direct action of nitrazepam on germ cells and/or Sertoli cells rather than by indirect action through inhibition of testosterone secretion.

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To determine an appropriate administration period and sensitive endpoints for the evaluation of effects on male fertility, male Sprague-Dawley rats were orally given nitrofurazone, a model compound, at doses of 12.5, 25, or 50 mg/kg/day for 4 weeks, or at doses of 12.5 or 25 mg/kg/day for 9 weeks before mating with untreated females. Copulation and fertility indices were decreased, and pregnancy did not result at doses of 25 mg/kg/day and over with both dosing periods. An increase in pre-implantation loss, and decreases in implants and live fetuses were observed with 12.5 mg/kg/day after 9-weeks dosing. However, no reproductive endpoints were affected by the same dose level for 4-weeks. Sperm head count was reduced at doses of 25 mg/kg/day and over with both dosing periods. Histopathology revealed tubular degeneration and interstitial cell hyperplasia at doses of 25 mg/kg/day and over after both periods of dosing. Moreover, failure of spermiation in tubular epithelia was also detected in the 12.5 mg/kg groups. These results suggest that 4-weeks premating exposure is sufficient for evaluation of the effects of nitrofurazone on male fertility, and the most sensitive endpoint in this 4-week premating-dose study is a histopathological change.

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Pyridoxine (PN) was intraperitoneally given at 250 and 500 mg/kg to male rats for 2, 4, or 6 weeks, and its effects on male fertility evaluated in terms of the optimal treatment period and detection parameters. Animals of all PN groups showed depression of body weight gains from week 1 of treatment onwards, significant at all but the 250 mg/kg 2 week administration 1 week time point. After 2 weeks treatment, the testes demonstrated only very slight histopathological changes. The 4- and 6-week treatments caused decreased spermatozoal motility and some histopathological changes in the testes including degenerate on of germinal epithelial cells with both doses and also decreases in the fertility index and mean velocity of sperm, reduction in the testes and epididymides weights, and changes in testicular proteins. In the animals undergoing a 4-week recovery period following 4 or 6 weeks exposure, changes disappeared with the 250 mg/kg dose, but still remained with 500 mg/kg. From these findings, it is concluded that a treatment period of 4 weeks is sufficient for evaluation of drug effects on male fertility and that histopathology can detect the slightest toxic effects on the testis.

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To determine the optimum period of drug treatment and assessment parameters to evaluate male fertility in rats, different methods of examination and periods of treatment before mating were investigated in Sprague-Dawley (Crj : CD) male rats treated with a testicular toxicity-inducing agent, reserpine. The rats were given reserpine subcutaneously at daily doses of 0.05, 0. 1 and 0.2 mg/kg for 4 and 9 weeks (4-week test and 9-week test). Reproductive performance was tested and after mating, the testes, epididymides, prostate and pituitary weights were measured. Sperm analysis arid histopathological examinations of the genital organs were also performed in the 4-week test case. After 4 weeks, prostate weight was decreased and the implantation rate showed a tendency for decrease. Histopathological examination of the testes revealed changes such as retention of step 19 spermatids in the seminiferous tubules of stages IX to XII, although sperm analysis showed no abnormal findings. In the 9-week test, testes and prostate weights were decreased along with the implantation rate was decreased. In conclusion, of the approaches used to evaluate the effects of reserpine on male fertility, histopathological examination and measurement of genital organ weights proved more sensitive than reproductive performance testing and sperm analysis. Regarding the optimum treatment period, 4 weeks was found to be sufficient for detection of histopathological and genital organ weight changes.

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