The potential of benidipine hydrochloride (BH), a 1,4-dihydropyridine calcium antagonist and a possible vasodilator, to protect against renal damage in the stroke-prone spontaneously hypertensive rat (SHR-SP) was examined using fifty-five males (10 weeks old). The animals were allotted into experiments 1 and 2, in each case subdivided into three groups (control and BH at doses of 3 and 10 mg/kg). Administration of BH was initiated before identification of clinical stroke in Experiment 1 and after its onset in Experiment 2. Measurement of body weight (BW) and systolic blood pressure (SBP) indicated that treatment of BH was associated with increased BW gain and reduced blood pressure in both experiments. Histopathological assessment revealed significant and dose-dependent decrease in the degree of fibrinoid necrosis in renal blood vessels, sclerosis, hyalinization, edematous thickening and Bowman's space dilatation in glomeruli, as well as protein casts, dilated or regenerative tubules, and interstitial inflammatory infiltration with fibrosis in tubulointerstitium in the BH treated groups as compared with the control group. These results indicated that BH exerts vasodilative effects on the kidney with improvement of regional blood flow, then preventing and ameliorating renal damage.

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6-Sulfanilamidoindazole (6SAI)-induced arthritis is one of the models for testing anti-inflammatory agents, and 6SAI induces not only acute arthritis mainly in hindpaws but also systemic inflammation including serositis and arteritis in rats. In this study, in order to clarify the distribution and early progression of articular lesions in this model, we have investigated the detailed pathologic changes in the joints in rats orally administered with 6SAI (500 mg/kg) daily for 7 days or 4 weeks. The articular lesions with similar histopathological changes in nature were systemically noted. In the early phase, mild focal mononuclear cell infiltration was noted in the synovium of joint and/or peritenon, or periarticular connective tissues. The lesions became edematous with infiltration of mononuclear cells and a small number of polymorphonuclear leukocytes and were replaced by granulation tissues later. In the more progressed phase, there were marked fibrosis in the synovium or periarticular tissues along with periosteal new bone formation, while the inflammatory changes mostly disappeared. The marked articular inflammation occurred frequently in tarsal, knee and carpal joints, and mild one in hip joint frequently. The lesions were only sporadically observed in the elbow, shoulder, and vertebrae. No changes were observed in the joints of neck and jaws. The initial changes in the tarsal joints which were most commonly and severely affected were focal monomuclear cell infilatration in the insertions of tendons and/or articular synovium. The present results indicate that 6SAI-induced arthritis may be closely related to physiological load on joints. In addition, it is suggested that the tarsal joint may be the most suitable in assessing anti-inflammatory effects of new agents in this model.

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6-Sulfanilamidoindazole (6SAI)-induced arthritis is one of the models for testing anti-inflammatory agents. In this study, in order to clarify the early histopathological changes in this model, the detailed histopathological examination was carried out on various organs and tissues in rats orally administered with 6SAI daily dose: (500 mg/kg) for up to 7 days. There were no histopathological changes in the control animals throughout the experimental period. In the 6SAI-treated animals, focal monomuclear cell infiltration in the insertions of tendons and/or articular synovium was observed in the tarsal joints from 1 day after the first treatment (1D), and the change was followed by edematous inflammation in the synovium, peritenon, and periarticular connective tissues. In the liver, edema with mononuclear cell infiltration was observed in the portal regions from 1D, and hypertrophy and increase in number of sinusoidal cells were usually found at 7D. Inflammatory lesions were also sporadically seen in the serosal tissues of various organs at 5 and 7D. From 2D, almost all animals showed hypertrophy of thyroid gland epithelial cells. Pyknosis of thymic cortical lymphocytes and adrenal gland hypertrophy were also seen in some animals. The present study revealed the characteristics of the early systemic histopathological changes in the 6SAI-induced arthritis model, and suggested that there may be some relationships between the articular and hepatic changes.

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We described the use of image analysis for determination of the intralobular distribution of microcystin-LR (L, L-leucine and R, L-arginine) and compared the results with liver injuries. Gray level was measured in each intralobular region and converted to optical density by using the equation, which was established by employing Kodak gray scales; the immunointensity was calculated by subtracting optical density in control animals from optical density in treated animals. When mice received a single injection of 0, 40.0, 48.0 or 57.6 μg/kg and were killed at 24 hours after treatment, immunointensity was increased in a dose-dependent manner. Microcystin-LR was localized most abundantly in the centrilobular region, moderately in the midlobular region, and slightly in the perilobular region. Higher frequency of apoptosis was only found in the centrilobular region at 57.6 and 48.0 μg/kg and in the midlobular region at 57.6 μg/kg. When mice received a single injection of 60.0 μg/kg and were killed at several time points within 24 hours, immunointensity showed a similar central-to-portal gradient in the hepatic lobule, attained the highest level at 11 hours, and then gradually decreased in a time-related manner. Microcystin-LR caused hemorrhage within 7 hours, followed by paracentral necrosis and apoptosis that were observed mostly in the centrilobular and midlobular regions. The results suggest that liver injuries might occur in association with the intensity and distribution of microcystin-LR.

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While polychlorinated biphenyls (PCB) are fat-soluble environmental pollutants stored breast fatty tissue and secreted in milk; the precise evidence of breast carcinoma from exposure to PCBs remains unclear. The aim of this study was to investigate the dose-response relationship in-utero and lactational exposure of PCBs congener for dimethlbenz[a]anthracene (DMBA)-induced rat mammary carcinogenesis. Female SD rats were injected (i.g.) with 25 pg, 2.5 ng, 250 ng, 7.5 μg of 3,3',4,4',5-pentachlorobiphenyl (PCB126)/kg, or the vehicle, on days 13 to 19 post-conception. Fifty-day-old female offspring were injected (i.g.) with 20 mg DMBA. The concentration of PCB in the liver of the 50-day-old was compared to the vehicle-group, found to be 530-fold higher in the 7.5 μg-group, nearly 21-fold higher in the 250 ng-group, nearly 2.4-fold in the 2.5 ng-group, and nearly 1.2-fold in the 25 pg-group. The expression of CYP1A1 in the liver of the 50-day-old was intensive in the 7.5 μg- and 250 ng-groups, and slight in the 2.5 ng-group, and not observed in the other groups. The observation was terminated when the pups were 170-day-old or the tumor size reached 20mm in diameter. The 7.5 μg-group showed a reduction of mammary carcinogenesis, but the 250 ng- and 2.5 ng-groups revealed increases incidence of carcinoma, while the 25 pg-group showed a similar incidence of the vehicle-group. The time course of tumor development of the 7.5 μg-group was significantly lower than that of the other groups, but that of the 250 ng-group was significantly higher, and that of the 2.5 ng- and 25 pg-groups was similar to that of the vehicle-group. Moreover, the tumors of the 250 ng-group showed the highest cell proliferation, anuploid tumor index, and nuclear grade when compared to those of the other groups. The present studies indicate that in-utero and lactational exposure of relatively low dose PCB acts as an enhancing agent toward DMBA-induced rat mammary carcinogenesis, but that of high dose PCB acts as an inhibiting agent. This effect partly may be due to the in vivo difference at the day of DMBA exposure (50-day-old); between the concentration of PCB and the expression of phase I drug-metabolize enzymes (CYP1A1) converting DMBA into the ultimate carcinogen.

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A modified Warthin-Starry (mWS) method was developed to stain apoptotic cells in tissue sections. Essentially the classical WS method is applied except for a minor change to prevent fading. In order to clarify the relationship between mWS-positive cells and apoptosis, apoptotic thymic tissues were examined on the rats treated with dexamethasone. The results clearly showed the distribution of mWS-positive cells to coincide well with that for apoptotic cells observed by terminal deoxynucleotidyl transferase (TdT)-mediated d-UTP-biotin nick end labeling (TUNEL) method. An additional characteristic is that nuclei of mitotic thymocytes, with highly condensed chromatin, are always stained. These observations suggest that the mWS method might be useful and convenient to detect condensed chromatin during apoptosis.

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Ear skin responses to picryl chloride (PCL) were examined in IQI/Jic male mice. Following the sensitization with PCL to the shaved abdominal skin, the left ear was topically applied with PCL at 4, 11, 18 and 25 days later. The ear swelling responses tended to shift from delayed type to immediate one after the 4th application. The peak time of histopathological changes characterized by edema and inflammatory cell infiltration corresponded well with that of ear swelling responses, and marked elevation of total serum IgE levels and prominent increase in number of mast cells were observed after the 4th application. The numbers of CD4⁺ cells and Mac-1⁺ cells began to increase after the 1st application and much more increased after the 4th application while CD8⁺ cells increased after the 4th application. MHC class II⁺ cells increased mainly in the dermis after the 4th application, but CD19 ⁺ cells, i.e. B lymphocytes, were negligible throughout the experimental period. The present results suggest that not only CD4⁺ cells but also CD8⁺ cells may participate in the induction of PCL-induced contact dermatitis in IQI/Jic male mice and that the shift from Th1-dominant response to Th2-dominant one may occur following the repeated application.

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Although both Prednisolone (PRE), a corticoid hormone, and diethylstilbestrol (DES), an estrogen-like hormone, are known to be immunosuppressive drugs, we found that mice pretreated with PRE showed enhanced resistance to Listeria infection, while mice pretreated with DES showed decreased resistance to Listeria infection. To establish useful immunoparameters of host resistance to Listeria infection, we examined the kinetics of immune cells in PRE- or DES-pretreated mice after non-lethal infection with Listeria monocytogenes. The number of CD4⁺CD8⁺, CD4⁺ and CD8⁺ T-cell subsets in the thymus and spleen and macrophage (Mac-1⁺ cells) in the spleen were decreased in mice pretreated with PRE, however the number of T-cell subsets in the thymus and macrophage in the spleen were remarkably increased to the level of non Listeria -infected control mice on Day 4 after Listeria infection. However, mice pretreated with DES showed a decrease in CD4⁺CD8⁺ T-cells in the thymus and a decrease in macrophages in the spleen. Furthermore, these cells continued to show decreased numbers even after Listeria infection. A remarkable increase of CD8:CD4 T-cell ratios was observed in PRE-pretreated mice but not in DES-pretreated mice. These data demonstrated that the recovery of CD4⁺CD8⁺, CD4⁺ and CD8⁺ T-cell subsets in the thymus, increased CD8:CD4 T-cell ratios in the thymus and increased macrophages in the spleen on Day 4 after the infection play important roles in increasing the resistance to Listeria infection in mice pretreated with PRE. These results also suggested that changes in immune cell kinetics could be good immunoparameters to demonstrate susceptibility to Listeria infection in mice pretreated with immunosuppressive drugs.

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The development of apoptosis and the expression of c-fos mRNA were investigated up to 24 hours after treatment (HAT) with 0.2 g/ml of T-2 toxin in Con A-stimulated primary thymocyte cultures prepared from BALB/c mice. Cell viability began to decrease from 1 to 3 HAT, and it was approximately 50% at 6 HAT. The level of cytoplasmic nucleosomes peaked at 3 HAT (about 2 times of control) and decreased thereafter. At 6 HAT, thymocytes showed irregular-shaped or fragmented nuclei. By RT-PCR, the level of c-fos mRNA began to increase within 1 HAT, and maintained a high level through the observation period. Preincubation with BAPTA/AM, a intracellular calcium ion chelator, markedly suppressed the expression of c-fos mRNA and the level of DNA fragmentation induced by T-2 toxin. Although less effective, preincubation with H-7, a protein kinase C (PKC) inhibitor, also depressed the above-mentioned two parameters. These findings indicate that, in mouse thymocyte primary cultures treated with T-2 toxin, c-fos may play an important role in the induction of apoptosis and the increase in intracellular calcium ion may be closely related with the expression of c-fos mRNA. In addition, these findings also suggest that PKC-dependent pathway may be involved in T-2 toxin-induced thymocyte apoptosis.

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Huge vacuoles in the follicular epithelial cells distributing diffusely in the thyroid gland were seen in 2 out of 36 males and 8 out of 82 females of BrlHan: WIST@Jcl (GALAS) rats examined histopathologically. The vacuoles showed negative reactivity by periodic acid-Schiff reaction and thyroglobulin-immunohistochemistry. Corresponding to the vacuoles, remarkable dilatation of rough endoplasmic reticulum was seen in electron microscopic observation. The animals in which the thyroid lesion was found had shown no abnormalities in behavior, body weight, food consumption, or hematological and biochemical examinations. Plasma concentrations of thyroid-stimulating hormone (TSH) and thyroid hormones (T3 and T4) were not different from those of normal rats. From these results, thyroid functions seemed to be kept normal in spite of the severe morphological change. Based on the character and incidence of the thyroid lesion, it was presumed to be related with a certain genetic factor of one or several parents of breeding rats rather than food contamination or infection.

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