Assessment of in vivo mutagenic potency of ethylenediaminetetraacetic acid in albino mice.

Ethylenediaminetetraacetic acid (EDTA) disodium salt, a widely used metal chelator, was studied for its potency to induce bone marrow micronuclei, dominant lethal mutations and sperm-head abnormalities in albino mice. The acute oral LD₅₀ dose computed by probit regression was 30 mg/kg body weight in the strain used. Preliminary studies showed that oral administration of EDTA disodium salt at doses of 5, 10 and 15 mg/kg body weight/day on 5 consecutive days did not induce any obvious signs of toxicity. In the bone marrow micronucleus assay acute doses of EDTA disodium salt (5–20 mg/kg body weight) induced a dose-dependent increase in the incidence of micronucleated polychromatic erythrocytes at a 24-hr sampling. However, administration at doses of 5, 10 and 15 mg/kg for 5 consecutive days did not produce any observable effect on either the testicular or epididymal weights and histology. No appreciable alterations were observed in the caudal sperm counts at any of the sampling intervals and there was no treatment-related increase in the incidence of sperm-head abnormalities. Furthermore, treatment of male mice with EDTA disodium salt (10 mg/kg body weight/day for 5 consecutive days) induced no increase in the incidence of post-implantation embryonic deaths, except for a marginal but statistically insignificant increase during wk 2 and 3 of mating.     

Assessment of in vivo mutagenic potency of ethylenediaminetetraacetic acid in albino mice

Ethylenediaminetetraacetic acid (EDTA) disodium salt, a widely used metal chelator, was studied for its potency to induce bone marrow micronuclei, dominant lethal mutations and sperm-head abnormalities in albino mice. The acute oral LD₅₀ dose computed by probit regression was 30 mg/kg body weight in the strain used. Preliminary studies showed that oral administration of EDTA disodium salt at doses of 5, 10 and 15 mg/kg body weight/day on 5 consecutive days did not induce any obvious signs of toxicity. In the bone marrow micronucleus assay acute doses of EDTA disodium salt (5–20 mg/kg body weight) induced a dose-dependent increase in the incidence of micronucleated polychromatic erythrocytes at a 24-hr sampling. However, administration at doses of 5, 10 and 15 mg/kg for 5 consecutive days did not produce any observable effect on either the testicular or epididymal weights and histology. No appreciable alterations were observed in the caudal sperm counts at any of the sampling intervals and there was no treatment-related increase in the incidence of sperm-head abnormalities. Furthermore, treatment of male mice with EDTA disodium salt (10 mg/kg body weight/day for 5 consecutive days) induced no increase in the incidence of post-implantation embryonic deaths, except for a marginal but statistically insignificant increase during wk 2 and 3 of mating.     

Reproductive toxicity evaluation of vanadium in male mice

The reproductive toxicity of vanadium was studied in mice. Male Swiss mice were exposed to sodium metavanadate at doses of 0, 20, 40, 60, and 80 mg/kg per day given in the drinking water for 64 days. To evaluate the fertility of the vanadium-treated animals, males were mated with untreated females for 4 days. A significant decrease in the pregnancy rate was observed at 60 and 80 mg/kg per day of sodium metavanadate. However, metavanadate did not reduce fertility in male mt 20 and 40 mg/kg per day. Reproductive toxicity was measured by sperm count, sperm motility, organ weights, and histologic evaluation of the testes. Decreased body and epididymis weight was only observed in the 80 mg/kg per day group, while testicular weights were not altered by the treatment with all doses used. Sperm coung was significantly decreased at 40, 60, and 80 mg/kg per day, but the sperm motility was unaffected. Histopathological examination revealed that the testes were normal and that the epididymis of treated male mice contained normal appearing sperm. The no observed adverse effect level (NOAEL) was 40 mg/kg per day. Consequently, vanadium would not cause any adverse effect on fertility or testicular function in male mice at the concentrations usually ingested by humansthrough the diet and drinking water.     

Diesel exhaust (DE) affects the regulation of testicular function in male Fischer 344 rats

To investigate the effects of diesel exhaust (DE) particles on the reproductive system, male Fischer 344 rats at 13 mo of age were exposed to clean air or DE at particle concentrations of 0.3, 1, or 3 mg/m3 for 8 mo. DE did not markedly affect testicular and body weights. However, DE at 0.3 mg/m3 significantly decreased prostate and coagulating gland weights, accompanied by a reduction in thymus and adrenal gland weight. In contrast, there was a significant rise in the weights of prostate, seminal vesicles, and coagulating glands in the 3 mg/m3 DE group. In rats exposed to 0.3 or 1 mg/m3 DE, serum luteinizing hormone (LH) and testosterone increased significantly, while a rise in testicular testosterone was noted with 3 mg/m3 DE. The concentrations of follicle-stimulating hormone (FSH) and inhibin as well as the sperm head counts were not markedly altered in any treatment group. Positive staining with inhibin-alpha subunit and 3beta-hydroxysteroid dehydrogenase (3beta-HSD) were observed in Sertoli cells and Leydig cells, respectively. Immunolocalization of inhibin-alpha subunit and 3beta-HSD was not changed by exposure to DE. In conclusion, DE appears to exert greater effects on accessory glands than on testes in Fischer 344 rats, and the responsiveness of rats is less than that found in mice.     

Fertility and early embryonic development toxicity of penequine hydrochloride in mice.

Penequine hydrochloride, a novel anticholinergic agent, was developed as an effective treatment for organophosphorus intoxication. The potential for penequine hydrochloride to induce fertility and early embryonic developmental toxicity was evaluated in AMMS-1 mice. Totally 320 healthy, sexual mature and nulliparous AMMS-1 mice were orally treated with the chemical in drinking water at dose levels of 0, 2.5, 12.5 and 62.5 mg/L from 60 days before cohabitation to successful copulation in 160 males and from two weeks before cohabitation to GD 6 in 160 females, respectively. All the parental mice were observed for body weights, water consumption and any abnormal change during treatment period. Caesarean sections were carried out on day 14 of pregnancy in half assumed-pregnant females, and all the intrauterine data were recorded. Pups naturally delivered by the other half females were weighed, and examined for viability, sex ratio and gross malformations. About 7 days after cohabitation period, all the paternal males were examined for epididymal and testicular weights, sperm number and sperm motility. The decreases in fertility/fecundity indices and maternal weight gain were found at high-dose level in both caesarean sections and natural delivery observations. The primary developmental toxicity of the chemical included decreases in relative organ (epididymis, liver and lung) weights at mid- and high-dose levels in pups on postnatal day (PND) 35. The cause of both the decreased fertility/fecundity indices in F0 males and the decreased relative organ weights in F1 pups are not well known but are presently under investigation. Under the experimental conditions, penequine hydrochloride did not produce any adverse effects (expect the decreases in certain relative organ weights) up to and including 12.5 mg/L (2.53 mg/kg/day in males and 2.19 mg/kg/day in females) corresponding to approximately 72 times above anticipated dosage in human.     

Effects of abamectin exposure on male fertility in rats: potential role of oxidative stress-mediated poly(ADP-ribose) polymerase (PARP) activation

Despite the known adverse effects of abamectin pesticide, little is known about its action on male fertility. To explore the effects of exposure to abamectin on male fertility and its mechanism, low (1 mg/kg/day) and high dose (4 mg/kg/day) abamectin were applied to male rats by oral gavage for 1 week and for 6 weeks. Weight of testes, serum reproductive hormone levels, sperm dynamics and histopathology of testes were used to evaluate the reproductive efficiency of abamectin-exposed rats. Abamectin level was determined at high concentrations in plasma and testicular tissues of male rats exposed to this pesticide. The testes weights of animals and serum testosterone concentrations did not show any significant changes after abamectin exposure. Abamectin administration was associated with decreased sperm count and motility and increased seminiferous tubule damage. In addition, significant elevations in the 4-hydroxy-2-nonenal (4-HNE)-modified proteins and poly(ADP-ribose) (PAR) expression, as markers for oxidative stress and poly(ADP-ribose) polymerase (PARP) activation, were observed in testes of rats exposed to abamectin. These results showed that abamectin exposure induces testicular damage and affects sperm dynamics. Oxidative stress-mediated PARP activation might be one of the possible mechanism(s) underlying testicular damage induced by abamectin.     

trans-resveratrol relaxes the corpus cavernosum ex vivo and enhances testosterone levels and sperm quality in vivo

We examined the effects of trans-resveratrol on male reproductive functions; ex-vivo penile erection and in-vivo sperm counts and quality. For the ex-vivo study, the relaxation effects of resveratrol on isolated New Zealand white rabbit corpus cavernosum, precontracted by phenylephrine (5×10⁻⁵ M) were measured. The in-vivo study measured reproductive organ weights, blood testosterone levels, testicular histopathology, sperm counts, as well as the epididymal sperm motility and deformity of male ICR mice given an oral dose of resveratrol (50 mg/kg) for 28 days. Resveratrol elicited a concentration-dependent relaxing effect on corpus cavernosum, leading to a median effective concentration (EC₅₀) of 0.29 mg/mL. Repeated treatment with resveratrol (50 mg/kg) did not cause an increase in body weight, reproductive organ weight or testicular microscopic findings; however, resveratrol did elicit an increase in blood testosterone concentration, testicular sperm counts and epididymal sperm motility by 51.6%, 15.8% and 23.3%, respectively, without influence on sperm deformity. In conclusion, we propose that resveratrol has a positive effect on male reproductive function by triggering a penile erection, as well as enhancing blood testosterone levels, testicular sperm counts, and epididymal sperm motility.     

Testicular toxicity of dietarily or parenterally administered bisphenol A in rats and mice.

Male Crj:Wistar rats, HsdHot:Holtzman SD rats, Crj:CD-1(ICR) mice and C57BL/6CrSlc mice were administered bisphenol A (BPA) in the diet at a level of 0 (control) and 0.25% for 8 weeks. Daily BPA intake was about 200 and 400 mg/kg for rats and mice, respectively. No conspicuous signs of general or reproductive toxicity were observed after administration in any strain of these animals. Serum testosterone concentrations were not decreased in BPA-fed rats and mice. Successive subcutaneous administration of BPA at a dose of 200 mg/kg/day for 4 weeks significantly decreased the testis, epididymis, prostate and seminal vesicle weights, and the testicular daily sperm production in Jcl:Wistar rats. Successive intraperitoneal administration of BPA at a dose of 20 mg/kg/day for 4 weeks decreased the prostate and seminal vesicle weights but not the testis or epididymis weights. An intraperitoneal dose of 2 mg BPA/kg/day did not cause any toxicity. These results indicate that dietarily administered BPA is less toxic to most strains of rats and mice, and the maximum non-toxic dose and/or minimum toxic dose may be about 200 mg/kg/day. Subcutaneous or intraperitoneal BPA is much more toxic on male reproductive and sex accessory organs than dietary.     

Effect of nonylphenol on the antioxidant system in epididymal sperm of rats

Nonylphenol, an environmental contaminant, has been shown to induce reproductive abnormalities in male rats. The nature and mechanism of action of nonylphenol on the epididymal sperm has not been elucidated. In the present study we have sought to investigate whether administration of nonylphenol induces oxidative stress in rat epididymal sperm. Nonylphenol was administered orally to male rats at 1, 10 and 100 microg/kg body weight per day for 45 days. Twenty-four hours after the last treatment, rats were weighed and killed using anaesthetic ether. The body weight of the animals treated with nonylphenol did not show any significant change. The weights of the testes and epididymides decreased significantly whereas the weights of seminal vesicles and ventral prostate remained unchanged at all doses of nonylphenol in treated rats. Epididymal sperm were collected by cutting the epididymides into small pieces in Ham's F-12 medium at 32 degrees C. Administration of nonylphenol decreased the epididymal sperm counts in a dose-dependent manner. The activities of antioxidant enzymes superoxide dismutase, catalase, glutathione reductase and glutathione peroxidase decreased significantly while the levels of H(2)O(2) generation and lipid peroxidation increased significantly in the animals treated with nonylphenol when expressed in terms of milligram protein and milligram DNA. The activity of alpha-glucosidase, a negative control against antioxidant enzymes, in the sperm of nonylphenol-treated rats did not show any significant change at any of the doses. The results suggest that graded doses of nonylphenol elicit depletion of antioxidant defence system in sperm, indicating nonylphenol-induced oxidative stress in the epididymal sperm of rats.     

Reproductive toxicity of 2-methoxyethanol applied dermally to occluded and nonoccluded sites in male rats

12-Methoxyethanol (2-ME), also known as Methyl Cellosolve, was applied on the backs of Sprague-Dawley male rats at dose levels of 0, 625, 1250, or 2500 mg/kg/day on occluded (covered) sites, and 0, 1250, 2500, or 5000 mg/kg/day on nonoccluded (uncovered) sites for 7 consecutive days. Because deaths occurred at a dose level of 2500 mg/kg/day among rats with occluded test sites, dosing of this group was discontinued after 5 days. The number and morphology of caudal epididymal sperm, number of testicular spermatids, and weights of reproductive organs were determined on Weeks 4, 7, 10, and 15; fertility was assessed on Weeks--1, 4, 7, 10, and 14. The effects of treatment were dose-related and included a decline in epididymal sperm count and testicular spermatid count, a reduction in weights of testes and epididymides, an increase in the number of sperm with abnormal morphology, and a reduction in fertility in rats exposed to 2-ME. The above effects were seen with or without occlusion, but they were more severe and recovery proceeded at a slower rate when the skin sites were covered.     

Assessment of the Reproductive Toxic Potential of Dermally Applied 2-Hydroxy-4-methoxybenzophenone to Male B6C3F1 Mice

The potential of 2-hydroxy-4-methoxybenzophenone (HMB) to causemale reproductive toxicity was assessed in B6C3F1 mice. HMBwas administered topically for 13 weeks (5 days/week) to groupsof 10 mice each at dosages of 0, 10, 20, 100, or 400 mg/kg/day.Additional high dosage and control mice were also included andeuthanized at interim time points to characterize the time courseof any effects. After 91 days (or at interim periods) mice wereeuthanized and reproductive organ weights, cauda epididymalsperm concentration and proportion of motile and abnormal sperm,and testicular spermatid concentration were determined. Testicularhistology was evaluated in fixed tissue. HMB treatment had noeffect on body weight gain or any of the male reproductive parametersassessed at any time point. These results indicate that topicallyapplied HMB has no reproductive toxic potential in male B6C3F1mice at dosages as high as 400 mg/kg/day.     

Effect of oral administration of 1,3-diphenylguanidine on sperm morphology and male fertility in mice.

An oral testicular toxicity and male fertility study was carried out in CD-1 mice with 1,3-diphenylguanidine (99.9% purity). 1,3-Diphenylguanidine was administered to male mice by daily gavage at dose levels of 0, 0.06, 0.25, 1, 4 and 16 mg/kg body wt. per day during an 8-week premating period. Females were not dosed at any time during the study. Sperm abnormality evaluation was performed in approximately half the males, randomly selected from the control and 16-mg/kg dose group on completion of dosing. The remaining males in the control, 4- and 16-mg/kg body wt per day groups were mated with non-dosed females. Reproductive performance, necropsy findings and litter data were recorded. No differences were found between control and dosed groups in body weight gain during the dosing period, macroscopic observations and organ weights at necropsy. Microscopic examination of the testes and determination of the frequency of total sperm abnormalities in the 16-mg/kg body wt per day group, did not show any effect due to 1,3-diphenylguanidine dosing when compared to the control group, except for a slight increase in sperm with folded tails but normal heads. Male and female fertility as well as reproduction performance were comparable in the groups examined (0, 4 and 16 mg/kg body wt per day). Maternal necropsy findings and litter data did not reveal any dose-related effect. It was concluded that under the conditions of the present study, 1,3-diphenylguanidine did not exert any significant adverse effects on fertility, reproductive capacity or embryonic/fetal development in CD-1 mice when administered to males at levels up to 16 mg/kg body wt per day.     

Effect of 1,3-dinitrobenzene on prepubertal, pubertal, and adult mouse spermatogenesis

Exposure of prepubertal, pubertal, and adult mice to 0, 8, 16, 32, 40, or 48 mg 1,3-dinitrobenzene (m-DNB)/kg body weight and measuring responses 1-25 d posttreatment (dpt) demonstrated significant effects on testicular function only at 48 mg/kg dosage. m-DNB had no effect on body or testis weights with the exception of reduced adult mouse testis weights at 22 dpt with 48 mg/kg (p less than .05). None of the exposures resulted in detectable levels of germinal epithelial cells in the ductus epididymis. Exposure of prepubertal and pubertal mice to m-DNB caused only minimal nonsignificant changes in the relative percent of testicular cell types present up to 25 dpt. The adult mice testicular cell type ratios, in particular the round and elongating spermatid populations, changed significantly at doses of 48 mg/kg. Also, a reduction in the percent tetraploid cells occurred at d 1, suggesting these cells may be a primary target of m-DNB action. Caput and caudal sperm from mice exposed to m-DNB prior to puberty did not demonstrate an increased susceptibility to DNA denaturation when analyzed by the sperm chromatin structure assay. However, in pubertal mice, m-DNB exposure further exaggerated the abnormal chromatin structure that normally characterizes sperm during the onset of sperm production. In adult mice, 48 mg/kg resulted in increased susceptibility to DNA denaturation of caput sperm chromatin at 11 dpt (p less than .05) and in caudal sperm at 22 dpt (p less than .01). The abnormal chromatin structure of cauda sperm from adult mice was highly correlated with sperm head morphology abnormalities (ABN; 0.82 to 0.95, p less than .01, 11 and 22 dpt, respectively), but showed lower correlations with dose (0.60 to 0.79, p less than .01, 11 and 22 dpt, respectively). For pubertal mice, a positive relationship was also observed between the variation of sperm chromatin structure abnormalities and ABN. The effect of m-DNB on testicular function in prepubertal and pubertal mice appear to be less pronounced than in adult mice. Furthermore, following exposure to the same dosage, the effect of m-DNB is less severe in adult mice than that observed for adult rats as reported in the companion paper.     

Increased sensitivity to testicular toxicity of transplacental benzo[a]pyrene exposure in male glutamate cysteine ligase modifier subunit knockout (Gclm-/-) mice

Polycyclic aromatic hydrocarbons (PAHs), like benzo[a]pyrene (BaP), are ubiquitous environmental pollutants formed by the incomplete combustion of organic materials. The tripeptide glutathione (GSH) is a major antioxidant and is important in detoxification of PAH metabolites. Mice null for the modifier subunit of glutamate cysteine ligase (Gclm), the rate-limiting enzyme in GSH synthesis, have decreased GSH concentrations. We investigated the effects of Gclm deletion alone on male fertility and spermatogenesis and its effect on the sensitivity of male embryos to the transplacental testicular toxicity of BaP. Gclm-/- males had dramatically decreased testicular and epididymal GCL enzymatic activity and total GSH concentrations compared with Gclm+/+ littermates. Ratios of reduced to oxidized GSH were significantly increased in Gclm-/- testes. GSH reductase enzymatic activity was increased in Gclm-/- epididymides. We observed no changes in fertility, testicular weights, testicular sperm head counts, or testicular histology and subtle changes in cauda epididymal sperm counts, motility, and morphology in Gclm-/- compared with Gclm+/+ males. Prenatal exposure to BaP from gestational day 7 to 16 was dose dependently associated with significantly decreased testicular and epididymal weights, testicular and epididymal sperm counts, and with vacuolated seminiferous tubules at 10 weeks of age. Gclm-/- males exposed prenatally to BaP had greater decreases in testicular weights, testicular sperm head counts, epididymal sperm counts, and epididymal sperm motility than Gclm+/+ littermates. These results show no effects of Gclm deletion alone on male fertility and testicular spermatogenesis and subtle epididymal effects but support increased sensitivity of Gclm-/- males to the transplacental testicular toxicity of BaP.     

Assessment of male reproductive system in the CD-1 mice following oral manganese exposure

Manganese has wide industrial applications and exposure to manganese can result in serious health conditions. The purpose of this study was to determine the reproductive effect of oral manganese exposure in male mice. Manganese acetate was tested at three dose levels (7.5, 15.0, and 30.0 mg/kg/day) for 43 days. The control group (0 mg/kg/day) received distilled water. Control negative group did not receive anything. Reproductive organ weights were recorded. Histopathology was performed on right testis, epididymis, seminal vesicle, and the accessory glands. Cauda epididymal, testicular sperm counts, and sperm motility was evaluated on the organ from the left side. The results of this study suggest that exposure to manganese caused a statistically significant (P<0.001) decrease in sperm motility and sperm counts at 15.0 and 30.0 mg/kg/day. There were no alterations in the fertility or pathology of the testicular tissue in the manganese-treated mice when compared with the controls.     

Effects of the fungicide methyl-benzimidazol-2-yl carbamate (MBC) on mouse germ cells as determined by flow cytometry

Dual-parameter (DNA, RNA) flow cytometry (FCM) measurements were made on testicular and epididymal sperm cells isolated from mice exposed by oral gavage to 0, 250, 500, or 1000 mg/kg X 5 d of the fungicide methylbenzimidazol-2-yl carbamate (MBC), which is known to bind with tubulin subunits and inhibit polymerization and microtubule formation. Effects of exposure to MBC were measured at 7, 24, and 39 d posttreatment. MBC had no effect on body weights, but testis weights and sperm parameters were altered, with few exceptions, only at the highest exposure level. Testis weights were reduced by about 25% at 7 and 24 d after exposure; recovery was observed by 39 d after treatment. FCM measurements of testicular cells showed relative percentages of certain testicular populations (round, elongating, and elongated spermatids) were different from the control pattern 7 and 24 d after treatment. The mean percent of cauda epididymal sperm head morphology abnormalities and the susceptibility of the nuclear DNA to denaturation were both elevated at 7, 24, and 39 d after exposure to 1000 mg/kg. The level of denaturation was determined by FCM measurements of the metachromatic shift in acridine orange (AO) stained sperm nuclei from green (native DNA) to red (single-stranded DNA) fluorescence and quantitated by the expression alpha t[red/(red + green] fluorescence. These data demonstrate that spermatogenesis is sensitive to high-dose MBC exposure resulting in an altered ratio of testicular cell types present, abnormal sperm head morphology, and an altered sperm chromatin structure.     

Curcumin and kolaviron ameliorate di-n-butylphthalate-induced testicular damage in rats

The present study was carried out to evaluate the ameliorative effects of kolaviron (a biflavonoid from the seeds of Garcinia kola) and curcumin (from the rhizome, Curcuma longa L.) on the di-n-butylphthalate (DBP)-induced testicular damage in rats. Administration of DBP to rats at a dose of 2 g/kg for 9 days significantly decreased the relative testicular weights compared to the controls, while the weights of other organs remained unaffected. Curcumin or kolaviron did not affect all the organ weights of the animals. While only DBP treatment significantly increased the testicular malondialdehyde level and gamma-glutamyl transferase activity (gamma-GT), it markedly decreased glutathione level, the testicular catalase, glucose-6-phosphate dehydrogenase, superoxide dismutase, sperm gamma-GT activities and serum testosterone level compared to the control group. Data on cauda epididymal sperm count and live/dead ratio were not significantly affected in the DBP-treated rats. Alone, DBP treatment resulted in a 66% decrease in spermatozoa motility and a 77% increase in abnormal spermatozoa in comparison to control. DBP-treated rats showed marked degeneration of the seminiferous tubules with necrosis and defoliation of spermatocytes. The DBP-induced injuries in biochemical, spermatological parameters and histological structure of testis were recovered by treatment with kolaviron or curcumin. The pattern in the behaviour of these compounds might be correlated with their structural variations. Our results indicate that kolaviron and curcumin protect against testicular oxidative damage induced by DBP. The chemoprotective effects of these compounds may be due to their intrinsic antioxidant properties and as such may prove useful in combating phthalate-induced reproductive toxicity.     

Subchronic inhalation study of 1-hexene in Fischer 344 rats.

The objective of this study was to evaluate the toxicity of 1-hexene following repeated inhalation exposures in male and female Fischer 344 rats. Groups of 40 male and 40 female rats were exposed for 6 hours per day, 5 days per week, over a 13-week period. Treatment groups consisted of air-exposed control (0 ppm) and three test groups of 300, 1000, and 3000 ppm 1-hexene. During the treatment period, the rats were observed daily for clinical signs of toxicity; body weights and neuromuscular coordination [females only] were measured at 7-day intervals. After 7 weeks of exposure and at the end of the treatment period, the rats were subject to macroscopic and microscopic pathology, clinical chemistry, hematology, urinalysis, and sperm counts. No mortalities were observed during the course of the study. No clinical signs of toxicity attributable to 1-hexene exposure were observed. Female rats exposed to 3000 ppm had significantly lower body weights compared to control rats from exposure day 5 persisting throughout the treatment period. Male rats exposed to 3000 ppm had slightly but not statistically significant lower body weights in comparison to controls. Male rats exhibited slightly increased absolute and relative testicular weights, and female rats had slightly decreased absolute [but not relative] liver and kidney weights, at 3000 ppm. There were no gross or microscopic morphological findings attributed to treatment. Exposure to 1-hexene did not affect neuromuscular coordination in females as determined using the Rotarod, nor sperm counts in male rats. Several statistically significant effects in hematology, clinical chemistry, and urinalysis evaluations were observed, but were either of small magnitude or did not correlate with histopathological findings, and thus did not appear to be of biological significance. In summary, the no-adverse-effect-level for this study was determined to be 1000 ppm, based on decreased weight gain in female rats, and on slight organ weight changes in both sexes at 3000 ppm.     

Corticosterone does not cause testicular toxicopathology in the rat: relevance to methylxanthines, ACTH and stress.

1. Methylxanthines, ACTH and stress are well known to produce testicular pathology (e.g. seminiferous tubule atrophy). Methylxanthines, ACTH and stress alter hormone secretion, particularly from the pituitary-adrenocortical system. Consequently, it has recently been suggested that there may be a causal relationship between changes in endogenous physiological adrenocortical secretions, particularly corticosterone, and testicular pathology. 2. This study tested the hypothesis that corticosterone mediates the testicular effects of both methylxanthine treatment and stress. Corticosterone was administered daily by subcutaneous injection to groups of 10 male rats at dose levels of 2 or 20 mg kg-1 in propylene glycol (1 ml kg-1) for 1 month (the shortest duration of methylxanthine or ACTH exposure known to produce testicular pathology). The highest dose of corticosterone resulted in plasma concentrations that closely matched values resulting from stress (200-700 ng ml-1) compared with controls (< 25 ng ml-1). 3. The highest dose of corticosterone caused reduced body weight gain, lower thymus, adrenal, seminal vesicle and prostate weights, but did not induce any testicular pathology. 4. That a high, but physiologically relevant, dose of corticosterone did not cause testicular pathology in this experiment excludes this steroid in the direct aetiology of methylxanthine, ACTH and stress-induced testicular pathology. Other steroids secreted from the adrenal, in combination with corticosterone, may be involved.     

Testicular cytotoxicity of DA-125, a new anthracycline anticancer agent, in rats

To assess the testicular cytotoxicity induced by DA-125, a new anthracycline anticancer agent, 50 male Sprague Dawley rats were randomly assigned to five groups, with 10 rats in each group, and were given different single intravenous doses of DA-125 at dose levels of 0, 6.25, 12.5, 25, and 50 mg/kg body weight. On Day 56 after treatment, all male rats were killed and necropsied. Parameters of testicular cytotoxicity included genital organ weights, testicular sperm head counts, epididymal sperm motility and morphology, repopulation index, epididymal index, and histopathologic examinations. At 25 and 50 mg/kg, the weights of testes, epididymides, and seminal vesicles were reduced dose-dependently, but prostate weight was not different among the groups. At 50 mg/kg, the number of testicular sperm heads was decreased. However, the motility and morphology of epididymal sperm were comparable to the control values. On histopathologic examination, atrophy of seminiferous tubules, loss or decrease of germ cells, formation of multinucleated giant cells, and/or vacuolization of Sertoli cells in the testis were observed at 25 and 50 mg/kg. In addition, decreased sperm content and increased degenerative germ cells in the ductus epididymis were also found. Some recovery of spermatogenesis was observed at 25 mg/kg, whereas a decline in the repopulation index was observed at 50 mg/kg, indicating that the surviving stem cells had become unable to produce differentiated germ cells to enter the spermatogenic pathway. There was no evidences of testicular cytotoxicity at 6.25 and 12.5 mg/kg. These results indicate that administration of a single dose of DA-12.5 (25 to 50 mg/kg) results in testicular damage in male Sprague-Dawley rats.