Effects of ascorbic acid supplementation on the activity of acid phosphatase (ACP), alkaline phosphatase (ALP), glutamic oxaloacetic transaminase (GOT) and glutamic pyruvic transaminase (GPT) on liver, kidney and serum in cyclophosphamide-treated female virgin rats were investigated. Oral administration of cyclophosphamide at the dose of 5 mg/kg body weight/day for 12 days resulted in a significant elevation in ACP and ALP activities in liver, kidney and serum. Ascorbic acid supplementation at the dose of 25 mg/kg body weight/day showed a significant protection in the activity of ACP in liver, kidney and serum, but only in ALP activity in kidney. ALP activities in liver and serum were not restored to control level by ascorbic acid supplementation. Activities of GOT and GPT were elevated significantly in liver, kidney and serum after cyclophosphamide treatment, and were protected and restored to control level by ascorbic acid supplementation.
Time course changes in thyroid proliferative lesions as well as related hormone levels in the blood of male F344 rats given N-bis (2-hydroxypropyl) nitrosamine (DHPN: 2800 mg/kg body weight, single s.c. injection) as an initiation treatment followed by pulverized basal diet containing 0% (Group 2), 2% (Group 3) or 4% (Group 4) kojic acid (KA) were examined at Weeks 1, 2, 4, 8 and 12. As an untreated control group (Group 1), rats were given basal diet for 13 weeks and examined in the same manner. Serum T3/T4 levels in the DHPN+2% KA and DHPN+4% KA groups were significantly reduced as compared with the DHPN-alone group at each time point. Serum TSH levels in both DHPN+KA groups were significantly increased at each time point in a treatment period-dependent manner from Weeks 1 to 12, and the extent of elevation was more remarkable in the DHPN+4% KA group. At Week 2, there were no statistically significant intergroup differences in liver T4-UDP-GT activities on a milligram microsomal protein basis. Histopathologically, no thyroid proliferative lesions were observed in the untreated control group or the DHPN-alone group. However, diffuse follicular cell hypertrophy and decreased colloid in the thyroid were apparent in all rats of the DHPN+KA groups at each time point. In addition, local follicular cell hyperplasias and adenomas of the thyroid were observed at high incidence in the DHPN+2% KA group from Week 4 and in the DHPN+4% KA group from Week 8. Multiplicities of focal follicular cell hyperplasias and adenomas of the thyroid in the DHPN+2% KA group were significantly greater than those in the DHPN+4% KA group at Week 8. In the pituitary, an increase in the number of TSH producing cells with expanded cytoplasm was apparent from Weeks 4 to 12 in both DHPN+KA groups. These results strongly suggest that thyroid proliferative lesions were induced by KA administration due to continuous serum TSH stimulation through the negative feedback mechanism of the pituitary-thyroid axis, resulting from depression of serum T3 and T4.
Carbaryl, a carbamate pesticide, (LC50 15.08 mg/l for 96 hr, i. e. lethal concentration with 50% mortality) induced perturbations in the levels of certain biochemical components including the activities of some enzymes in the blood and liver of the fresh-water catfish, Clarias batrachus exposed to sublethal concentrations (1, 2 and 4 mg/l) of the pesticide for 96 hr and 15 days. The pesticide caused a decrease in the levels of total protein and glucose with a concomitant increase in the levels of inorganic phosphate and lactic acid in fish serum. However, very little change was recorded in the serum cholesterol level. The treatment of the fish with carbaryl led to a marked increase in the activities of transaminases (GOT and GPT), phosphatases (acid and alkaline) and lactate dehydrogenase in the fish serum, the magnitude of the effect being dependent on the pesticide concentration and duration of exposure. The increase in lactic acid concentration with subsequent decrease in glucose concentration indicates an enhanced rate of glycolysis due to pesticide stress. Furthermore, the significant decrease in the activity of fish liver succinate dehydrogenase suggests that anaerobic metabolism was favored over aerobic oxidation of glucose through Kreb's cycle in order to mitigate the energy crisis for survival. The rise in the activities of transaminases and acid phosphatase due to pesticide intoxication suggest enhanced protein catabolism and probable hepatocellular damage in the organism.
(5R)-3-[2-((1S)-3-cyano-1-hydroxypropyl)benzothiazol-6-yl]-5-methoxymethyl-2-oxazolidinone (E2011) is a novel monoamine oxidase type-A (MAD-A) inhibitor. In order to assess toxicological profiles of E2011, doses of 0 (as controls), 30, 100 mg/kg of E2011 were administered to male and female Sprague-Dawley rats once a day for 13 weeks orally by gavage. No mortality or any toxic signs except salivation occurred due to E2011 treatment. Decreased body weight gain and food consumption, increases of alkaline phosphatase and increases of liver weight were the major treatment-related findings observed predominantly in the 100 mg/kg group. Histological examination revealed nuclear enlargement of hepatocytes with appearance of altered cell foci in some cases, and acinar atrophy in Harderian glands in the 100 mg/kg group. Since the histopathological findings in the liver were indicative of an ongoing carcinogenic process, glutathione S-transferase placental form (GST-P) positive hepatic foci were identified immunohistochemically and examined morphometrically. Although GST-P positive hepatic foci were detected in all groups including controls, the number and area of GST-P positive hepatic foci were significantly higher in female rats treated with 100 mg/kg than those in controls. In this paper, possible mechanisms of specific lesions in the liver and Harderian glands will be discussed.
The dose-dependence of di(2-ethylhexyl)phthalate (DEHP) hepatocarcinogenicity was investigated in male F344 rats which were initially injected with diethylnitrosamine (200 mg/kg, hp) and subjected to partial hepatectomy at week 3. The animals were administered DEHP in the diet at concentrations of 30, 300, 3000, or 12000 ppm starting 2 weeks after the DEN injection for up to 46 weeks and killed at weeks 8, 24, 48 and 52. Additional groups were given clofibrate (3000 ppm in diet) or basal diet instead of the DEHP diet. Incidences of hepatocellular carcinomas were 75% (9/12, P<0.01) for 12000 ppm, 10% (1/10) for 3000 ppm, 7% (1/14) for 300 ppm, 0% (0/13) for 30 ppm, 15% (2/13) for clofibrate, and 8% (1/13) for the basal diet group at week 52, 4 weeks after cessation of chemical feeding. Development of glutathione S-transferase placental form (GST-P) positive foci was only slightly increased by clofibrate-administration at week 52 and consistently lower than the control level in the DEHP-treated groups after 24 weeks. In contrast, GST-P negative eosinophilic foci were dose-dependently increased in the more than 300 ppm DEHP and clofibrate treated groups. At the 30 ppm dose level, however, no morphological changes were apparent in the liver. Thus, the non-observed effect level regarding the promotional activity of hepatocarcinogenesis was demonstrated at 30 ppm, the effects being predictable on the basis of development of GST-P negative eosinophilic foci.
Epididymal sperm motion in rats was characterized by computer-aided sperm motion analysis (CASA) with its correlation to testicular lesions in the 2-week treatment study, using three compounds which are known to affect different stages of germ cells. Mature male rats were treated daily for 2 weeks with α-chlorohydrin (α-CH, 5 mg/kg), cyclophosphamide (CP, 20 mg/kg) or nitrazepam (NZ, 20, 40, 60 mg/kg). Changes in sperm motion were detected only in the α-CH and 60-mg/kg NZ-treated groups. Of the sperm motion parameters, velocity and amplitude of lateral head displacement (ALH) were concomitantly reduced in these two groups with good correlation. With respect to the distribution of the values in parameters, however, α-CH shifted the values down within a small range with high percentages of motile sperm, while NZ distributed them over a wide range with low percentages of motile sperm. CP treatment showed no histopathological changes in advanced germ cells, though it showed a decrease in the number of early germ cells. NZ treatment affected round and elongating spermatids (∼step 14) at doses of 20 and 40 mg/kg, and affected also more advanced spermatids (∼step 19) at the dose of 60 mg/kg. α-CH treatment did not affect testicular histopathology. These findings indicate that 60-mg/kg NZ treatment reduced sperm motion as a result of lesions affected in elongated spermatids and α-CH reduced it by direct effects on epididymal spermatozoa. The present study indicates that in addition to percentage of motile sperm, the velocity and ALH can be useful to detect the changes in sperm motion caused by different actions of NZ and α-CH, though each compound showed a distinct distribution pattern of these parameters.
Sperm morphological examination, computer-assisted sperm analysis (CASA) and histopathologic examination of the testis and epididymis were performed for male rats treated orally with boric acid for 3 weeks at dosage levels of 50, 150 and 500 mg/kg/day, and treated males were mated with untreated females. None of the males treated with 500 mg/kg/day could impregnate untreated females. The fertility index showed a tendency to decrease in males treated with 150 mg/kg/day. At necropsy, the pre-implantation loss rate in females mated with males treated with 150 mg/kg/day was higher than the control values. Upon epididymal sperm analysis using the CASA system, all parameters including the number of sperm and sperm motions were found to be affected in males treated with 500 mg/kg/day, and the number of sperm, percent motile, velocities and amplitude of lateral head displacement (ALH) were affected in males treated with 150 mg/kg/day. Upon sperm morphological examination, head and tail abnormalities were observed in males treated with 150 and 500 mg/kg/day. In the histopathological examination, atrophy of the seminiferous tubules and multinucleated giant cells in the testes were observed in males treated with 500 mg/kg/day.
In order to confirm the relationship between glutathione-peroxidase (GSH-PO) localization and biological testosterone action in the rat ventral prostate, immunocytochemical localization of GSH-PO in glandular epithelial cells of the rat ventral prostate was investigated. In the untreated group, GSH-PO was predominantly demonstrated in glandular epithelial cells of the ventral prostate. Intracellular localization of GSH-PO in the glandular epithelial cells was mainly observed in cytoplasmic matrix near the rough endoplasmic reticulum and was occasionally noted as a small granular structure (GSH-PO-positive granule) at the supranuclear region. In a castrated animal, the intensity of GSH-PO staining in the glandular epithelial cells was remarkably decreased. By testosterone administration to the castrated animal, GSH-PO was clearly detected in the glandular epithelial cells. Intracellular localization of GSH-PO was mainly observed in cytoplasmic matrix and the number of GSH-PO-positive granules increased remarkably. These findings suggest that immunostainable GSH-PO in the glandular epithelial cells of the rat ventral prostate is testosterone-dependent, and that its staining patter is a useful marker for biological testosterone action.
Induction of unscheduled DNA synthesis (UDS) in hairless mouse epidermis by six chemicals was determined in an in vivo - in vitro assay by using a liquid scintillation counting method. Test chemicals were applied once onto two areas of the back of female hairless mice after stripping of the stratum comeum with adhesive tape to enhance skin penetration. After exposure, the skin samples were taken and cultured in a medium containing [3H]thymidine with or without hydroxyurea (HU, an inhibitor of replicative DNA synthesis). DNA of the epidermis was extracted, and incorporation of [3H]thymidine into DNA and the DNA content was determined with a liquid scintillation counter and a fluorescence spectrophotometer, respectively. Induction of UDS by chemicals was judged by calculation of the UDS index [(the ratio of DNA synthesis in the presence of HU to that in its absence) × 100]. A good correlation between UDS induction and organ specificity of carcinogens was observed. 4-Nitroquinoline 1-oxide, a skin carcinogen used as a positive control, induced a dose-dependent increase in the UDS index of approximately 12-fold at 2 hr after exposure, while 1, 2-epoxydodecane, a non-skin carcinogen applied as a negative control, did not increase the UDS index. Four other skin carcinogens induced dose-dependent increases in the UDS index; N-methyl-N'-nitro-N-nitrosoguanidine and diepoxybutane at 2 hr after exposure, and 7, 12-dimethylbenz[a]anthracene and benzo[a]pyrene at 24 hr after exposure. The results suggest that UDS is a good marker of the genotoxicity of skin carcinogens.
The present study investigated the toxicity of repeated subcutaneous cocaine administrations combined with oral doses of ethanol, and discussed the role of the toxic metabolite cocaethylene. Subcutaneous cocaine (70 mg/kg) was given to male ICR mice at 45 min after an oral administration of either ethanol (maximum 3 g/kg) (cocaine-ethanol group; n=50) or saline control (cocaine group; n=30), once per day, for up to 5 days. In the combined cocaine-ethanol group, the total frequency of death was significantly increased (86%) as compared to the cocaine group (40%). In both administration groups, regardless of the day of death, "late" deaths characterized by the late and unexpected onset of fatal symptoms could be differentiated from "early" deaths on the basis of the survival time after the last cocaine injection, the drug concentrations in the tissues at the time of death, and/or the observed physical disorders. In the combined cocaine-ethanol group, a late death group with survival times exceeding 12 hr and two early death groups could be differentiated, based on the presence or absence of cocaethylene and the different types of clinical symptoms. In the early death group in which cocaethylene could be detected, the volume of ethanol ingested was not significantly different from the late death group with large ethanol consumption and slow exacerbation of the respiratory and locomotive symptoms. Furthermore, the severity of the cocaine-induced seizures was also similarly decreased by ethanol. In the other early death group in which cocaethylene could not be detected, the volume of ethanol ingested was significantly lower than in the late death group, and seizures as severe as in the cocaine-only group were observed.
In the present study the systemic toxic potential of di-isononyl phthalate (DINP) was assessed in a 13-week study in marmosets. Particular attention was given to its potential for hepatic peroxisome proliferation. Three groups of four male and four female marmosets received DINP, by oral gavage administration, at dosages of 100, 500 or 2500 mg/kg/day for 13 weeks. A fourth group served as a concurrent Control group and received the vehicle (1% methylcellulose and 0.5% Tween) only. A fifth group received clofibrate at a dosage of 500 mg/kg/day to provide a positive Control for liver peroxisome activity. At the end of the treatment period, the animals were killed and their livers were removed. 3000 × g supernatant and microsomal subcellular fractions were prepared from homogenised liver by differential centrifugation. The peroxisomal marker enzyme activity, cyanide-insensitive palmitoyl CoA oxidase, was assayed in the former, while cytochrome P450 concentration and lauric acid 11- and 12-hydroxylase activities (selective for CYP2E1 and 4A, respectively) were assayed in the microsomes. No statistically significant changes were seen in any of these parameters measured following DINP treatment, compared with the Control. Clofibrate treatment resulted in an approximately 100% increase (p<0.01) in both male and female marmoset cyanide-insensitive palmitoyl CoA oxidase activity and a similar increase (p<0.05) in male (only) lauric acid 11-hydroxylase activity. No other changes were statistically significant at the 5% level. These data provide no evidence that DINP was acting as a peroxisome proliferator when administered to marmosets under the conditions of the study.