We examined the cellular functional changes in bone marrow macrophages dbtained from rats treated intraperitoneally with mitomycin C (MMC), subcutandously with 5-fluorouracil (5FU) or intraperitoneally with phenylhydrazine (PHZ) for 7 days to define the mechanisms of toxicity in the bone marrow. The functions of peripheral blood monocytes and bone marrow macrophages were also compared. MMC and PHZ caused anemial and MMC and 5FU leukocytopenia. Changes in nucleated cell counts were different among the three drug-treatment groups, and MMC- and PHZ-treated bone marrow macrophages were activated for responsiveness to interleukin-1 (IL-1), and their migration activity, intracellular components and enzyme activities were increased. On the other hand, cellular functions of bone marrow macrohhages of rats treated with 5FU were suppressed.
Teratogenic potential of cis-1-[4-(p-menthane-8-yloxy) phenyl] piperadine (YM9429) was assessed by in vitro culture method using fetal palatal tissues of CD rats. YM9429 induced fetal cleft palate in vivo in CD rats when dams were orally treated during days 11-14 of pregnancy at dose of 500 mg/kg/day, but no abnormalities were detected when treated on days 15-16 (Shibata, 1993). After 4 successive days oral treatment during days 11-14 of pregnancy, the maternal plasma levels of the drug were less than 5 μg/ml on day 15 and less than 1 μg/ml on day 16. After a single oral dosing on day 14, the fetal levels were approximately 0.3 μg/g-fetus at 2 hours post dosing. When the fetal maxillary regions removed from the normal fetuses on day 15 of pregnancy were cultured with YM9429 at the concentrations of 5 and 1 μg/ml-medium for 48 or 72 hours, normal and full contact of the palatal shelves was observed. These results supported the previous findings that YM9429 demonstrated no teratogenic effects in vivo by maternal treatment on days 15-16 of pregnancy, and suggested other mechanisms than the direct influences on the fetal palatal shelves in the latter phases of morphogenesis including reorientation, horizontal extension and adhesion.
The effect of nitrobenzene on several spermatogenic endpoints was examined to determine which endpoints were affected by chemicals, how changes in spermatogenic endpoints are related to decreases in the rate of male fertility, and how long a treatment period is needed before damage can be detected. An experimental group of male Sprague-Dawley rats was given nitrobenzene (60mg/kg, per os), a known inhibitor of male fertility, and a control group was given a diet of sesame oil (1 ml/kg, per os) alone. The rats were mated with normal proestrus females on days 7, 14, 21, 28, 42, 56 and 70 of treatment. Male rats were sacrificed on the day after mating, and sperm motility, progressive motility of sperm, sperm count and sperm morphology were examined. After 7 days of treatment, no changes were observed in the endpoints examined. However, the testicular and epididymal weights, sperm count, sperm motility and progressive motility decreased significantly by day 14. By day 21 sperm viability and the fertility index decreased, while increases were observed in the abnormal sperm rate and instances in which no motile sperm existed. However, even after 70 days of treatment, the copulation index was not affected. The most sensitive spermatogenic endpoints were determined to be sperm count and sperm motility, followed by progressive motility, viability, abnormal sperm rate and fertility index. The copulation index is not a meaningful endpoint for male fertility. Furthermore, a period of at least 14 days is necessary for evaluation of the effect of nitrobenzene on male fertility.
Biochemical indices of selenium (Se) deficiency (liver Se content and glutathione peroxidase (GSHPx) activity, and urinary ketone bodies during fasting) were measured in Se-deficient or Se-sufficient control rats with or without ingestion of 6-propyl-2-thiouracil (PTU). Male weanling Wistar rats (50 to 60 g) were fed on a Torula yeast-based Se-deficient diet (Se content, < 0.01 μg/g), or on the same diet supplemented with sodiurn selenite (0.1 μg Se/g). The rats were given 0.05% PTU solution or deionized water as drinking water. After feeding for 6 weeks, the rats given PTU showed severe inhibition of growth and marked decreases in serum thyroxine (T4) and 3, 5, 3'-triiodothyronine (T3) levels. Animals fed the Se-deficient diet showed remarkably low hepatic Se content and GSHPx activity compared to the Se-sufficient control rats, irrespective of PTU-ingestion. In the rats without PTU, the Se deficiency was accompanied by significantly elevated serum T4 and lower T3 levels. Urinary ketone body excretion during fasting was significantly higher in the Se-deficient rats than in controls, irrespective of serum thyroid hormone levels. These results suggest that the increase in urinary ketone body excretion in Se deficiency may be independent of serum thyroid hormone.
The dilating effect of prostaglandin (PG) E1 and E2 on the once-constricted ductus arteriosus (DA) was examined in newborn rats. The animals were given subcutaneously PGs 3hr after caesarean delivery. The ratio of the DA to the pulmonary artery (PA) was determined 15, 30, 60, 90 and 180 min after injection. Both PGE1 and PGE2 dilated the DA for over 90 min. The maximal effect appeared 15 or 30 min after injection. The DA/PA ratio was significantly higher in PGE2 than in PGE1. In addition, another series of newborn rats were given subcutaneously PGE2 6 hr after caesarean delivery to examine the age-related changes in the DA-dilating effect. The DA/PA ratio was significantly decreased in 6-hr-old pups than in 3-hr-old pups. These findings indicate that both PGE1 and PGE2 have a dilating effect on the once-constricted DA and that the effect decreases with time.
The study has been performed to compare the ability of mouse peritoneal macrophages to ingest various types (catalase positive and negative) of bacteria and compared the influence of various sera on intracellular killing of Escherichia coli (2 (E. coli C). Among the tested microbes only E. coli C was ingested very luxuriantly and other organisms were taken up luxuriantly and moderately by mouse peritoneal resident macrophages (RMQs). Broad difference of ingestion was found even within the same genus (i.e., E. coli B and E. coli C). Intracellular killing of E. coli C by RMQs also varied depending on the type of serum. The maximum intracellular killing was found in the presence of normal mouse serum, although the difference was not much. The study has revealed that bacterial ingestion and intracellular killing ability of RMQs varies depending on bacterial strains and sera respectively.
Haloperidol (HPL) was administered by presenting HPL-admixed food to 20 male and 19 female Sprague-Dawley rats from the age of 5 weeks at a target dose of 1.0 mg/kg/day for 80 weeks. The range of the actual daily dose was 0.48-1.11 mg/kg in males and 0.34-0.73 mg/kg in females. The control rats (13 males and 13 females) were given normal food. In the present study, the general condition and locomotor activity of these rats were examined. 1. The number of HPL-treated animals that died during the administration periods (11 males and 9 females) and the symptoms observed immediately before their death were comparable to those in the control group. Vacuous chewing movement developed in HPL-treated animals (12 males and 11 females) after the 28th week of administration. These movements showed a tendency of decrease after the 68th week. Blepharitis was observed in all females and 3 males of the HPL-treated group, but in none of the controls of either sex. Subcutaneous masses in the chest and abdomen were observed in 3 HPL-treated females and 6 control females, but there was no significant difference in their incidence between the two groups. 2. The body weight gain in the HPL-treated group was suppressed in males, but was promoted and then suppressed in females. The food consumption in the HPL-treated group was similar, but the water consumption was reduced in both sexes as compared with the control groups. 3. Locomotor activity was reduced in the HPL-treated group for both males and females, and no tolerance developed. These results suggest that HPL does not have a possibility to cause death even by chronic administration at the doses examined in the present study. However, the occurrence of body weight losses and blepharitis indicated the need for particular attention to these symtoms during chronic administration.
The so-called "decision tree" for computed programs for data analyses of toxicity studies indicates that, when a set of quantitative data is heterogeneity in variance among groups, then data should be transformed into ranked data to test the significant difference among mean values. However: 1. Hypothetical sets of data indicate that the minimum sample size needed to detect a significant difference among mean values by multiple-comparison test of ranked data is too large when compared with the practical number of animals (e.g. 4 dogs or 10 rats per sex per group) used in toxicity studies. 2. The homogeneity test of variances among groups may provide itself important information on the toxicity of test compound, as well as the test for significant differences among mean values indicates. 3. On the assumption that variances in data for most test items in toxicity studies are homogeneous as far as the test items are not greatly affected by the treatment with test compounds, it seems practical to test the significant difference among mean values by parametric procedures even if the data are heterogeneous in their variances among groups.
Effects of barbital (BB) on neuro-oncogenesis were examined in a rat transplacental carcinogenesis model. Pregnant F344 rats were divided into 7 groups. Dams in group I received subcutaneous injections of 10 mg/rat 1-butyl-1-nitrosourea (BNU) on the days 15, 18 and 21 of pregnancy and dams in groups II-IV, 1mg/rat BNU on the same time schcdule. In addition to the treatment with BNU, dams in group IV were given 0.125% BB solution as their drinking water from the day 12 of pregnancy to parturition. Offspring in groups III and IV received 0.125% BB solution as drinking water from 4 weeks of age until the termination of the study. Animals in groups V and VI were given 0.25% and 0.125% BB solutions, respectively, in the peri- and postnatal period without BNU treatment. Dams in group VII received 250 mg/kg BB sub-cutaneously on the days 15, 18 and 21 of pregnancy. Offspring in all groups were observed until 105-116 weeks of age. High yields of neurogenic tumors, such as gliomas and neurinomas, were observed in group I. In groups II, III and IV, single cases of a chordoma, a granular cell tumor, and a neurinoma and a malignant reticulosis, which are known to occur spontaneously, were noted, although no gliomas were found. No neurogenic tumors were observed in groups V-VII. With regard to lesions other than those in neurogenic organs, a significant increase in liver tumors was observed in group III compared to group II. In contrast, lung tumors were not found in group III, while they were observed in groups II and IV. These results suggest that BB has no neuro-carcinogenic activity in the rat transplacental carcinogenesis model.
The present paper focuses on the necessity of logarithmic transformation of plasma concentration in toxicokinetic studies. The dose-plasma concentration relationship is the most important subject to be studied, because test doses rise over a wide range from therapeutic dose level to toxic dose level in toxicity studies. It is concluded that the logarithmic transformation of concentration data effectively stabilized the variances, and the regression analysis of log-transformed data makes it possible to quantitatively evaluate the magnitude of non-linear kinetics of test compounds in toxicity studies.