The Zucker fatty (ZF) rat is a disease model of obesity and metabolic syndrome, such as hyperlipidemia and insulin resistance, resulting from hyperphagia owing to the loss of function of the leptin receptor, but it rarely develops hyperglycemia. We examined the effects of different doses of streptozotocin (STZ). A low dosage of STZ (30 mg/kg body weight, i.p.) elevated blood glucose levels in ZF rats up to 300 mg/dl within a week, and to nearly 500 mg/dl by 5 weeks after injection of STZ. Besides hyperglycemia, STZ-treated ZF (STZ-ZF) rats retained metabolic syndrome features such as hyperlipidemia and hyperinsulinemia. The stimulated insulin secretion in response to orally-loaded glucose disappeared completely in STZ-ZF rats. Although there were no significant differences in the morphology of pancreatic islets between vehicle-treated ZF (Cont-ZF) and STZ-ZF rats, the insulin content was markedly decreased in STZ-ZF rats. The hepatic gene expression for gluconeogenic enzymes was upregulated in STZ-ZF rats compared with Cont-ZF rats. Metformin lowered the blood glucose levels of STZ-ZF rats in a dose-dependent manner. These results suggest that STZ-ZF rats are useful for studies of T2DM and for the evaluation of the efficacy of anti-diabetic drugs.

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We examined the expression of VCAM-1 and MAdCAM-1 after bone marrow transplantation (BMT). We also examined the influence of α₄β₇ integrin blockade on the homing of cells to the bone marrow and spleen. The expression of VCAM-1 and MAdCAM-1 by endothelial cells in the spleen and bone marrow was examined by immunoelectron microscopy using colloidal gold and was analyzed semiquantitatively. To examine the role of α₄β₇ integrin in donor cells, a homing assay was conducted following α₄β₇ integrin blockade in bone marrow-derived hematopoietic cells or spleen colony cells. Immediately after BMT, the expression of VCAM-1 and MAdCAM1 markedly decreased, but expression recovered significantly between 12 and 24 h after BMT. VCAM-1 recovered more acutely than MAdCAM-1 from 12 h onward. In the group transplanted with anti-α₄β₇ integrin antibody-treated bone marrow cells, the numbers of homing cells in the spleen and bone marrow were significantly decreased in an antibody dose-dependent manner. However, the number of homing cells was not different in either the spleen or bone marrow between anti-α₄β₇ integrin antibody treated and untreated spleen colony cells. It has been reported that α₄β₁ integrin and its receptor VCAM-1 play major roles in the homing of hematopoietic cells to bone marrow. Our study indicates the importance of MAdCAM-1 and its ligand, α₄β₇ integrin, in the homing of bone marrow-derived hematopoietic cells, but not spleen colony-derived cells, to both the spleen and bone marrow.

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An enzyme-linked immunosorbent assay (ELISA) was developed to detect the antibody against lymphocytic choriomeningitis virus (LCMV) in sera of laboratory animals. In this ELISA system, LCMV-nucleoprotein (NP) expressed by recombinant baculovirus and purified with high molar urea was used as the antigen. Sera from laboratory animals experimentally infected with the Armstrong strain or the newly isolated M1 strain of LCMV were examined to detect anti-LCMV antibody by the ELISA system, and the reactivity was compared with that of IFA test. Regardless of LCMV strain, all the sera of adult mice infected with LCMV were positive with very high optical density (OD). Also, the sera from mice neonatally infected with LCMV M1 strain were positive with slightly lower OD than adult mice. In contrast, all the sera of uninfected mice were negative to LCMV-NP antigen. Similarly, anti-LCMV antibodies were detected in all the sera of hamsters, mastomyses, and gerbils infected with the LCMV Armstrong strain. The results of the ELISA were in complete agreement with those of IFA, and indicate the high sensitivity and specificity of the ELISA system in the detection of anti-LCMV antibody. Because this ELISA system does not require handling infectious LCMV in the course of the antigen preparation and serological assay, there is no risk of contamination in the laboratory or nearby animal facility. In addition, by using negative control antigen in parallel with positive antigen in ELISA, we can exactly check the LCMV contamination in laboratory animals.

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In laboratory animal facilities, monkeys and pigs are used for animal experiments, but the details of hepatitis E virus (HEV) infection in these animals are unknown. The risk of infection from laboratory animals to humans has become a concern; therefore, much attention should be paid to the handling of these animals during their care and use, including surgical procedures performed on infected animals. In this connection, serum samples collected from 916 monkeys and 77 pigs kept in 23 animal facilities belonging to the Japanese Association of Laboratory Animal Facilities of National University Corporations (JALAN) and the Japanese Association of Laboratory Animal Facilities of Public and Private Universities (JALAP) in Japan were examined for the purpose of detecting antibodies to HEV and HEV RNA by using ELISA and RT-PCR, respectively. One hundred and seven serum samples of 916 (11.7%) monkeys were positive for anti-HEV IgG, and 7 and 17 serum samples of 916 (0.8% and 5.3%) monkeys were positive for anti-HEV IgM and IgA, respectively. Thirty-six samples from 62 (58.1%) farm pigs were positive for anti-HEV IgG, whereas all samples tested from miniature pigs were negative (0/15, 0%). Seven samples from 62 (9.1%) farm pigs and 7 samples from 916 (0.8%) monkeys were positive for IgM antibody, but these HEV-IgM antibody positive serum samples were HEV-RNA negative by RT-PCR. The IgM antibody positive rate (9.1%) of farm pigs was much higher than that of monkeys (0.8%). These results suggest the relative levels of risk of HEV infection from these animals to animal handlers and researchers who work with them in laboratory animal facilities.

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The h current (Ih) is an inwardly mixed cationic conductance activated by membrane hyperpolarization. We previously demonstrated that the Ih blockers CsCl and ZD7288 can significantly increase the threshold of electrically induced paroxysmal discharge in the rabbit hippocampus. In the present study, we examined the effects of these Ih blockers on inherited epilepsy in Mongolian gerbils. Seizure-sensitive Mongolian gerbils (n=29) underwent a series of seizure induction tests (including gentle handling for 1-2 min and being dropped from a height of 50 cm) before, during and after oral administration of 10 mM CsCl or 0.1 mM ZD7288. Their behavioral responses were classified into 3 grades corresponding to no seizure (score: 0), partial seizure (score: 1), and generalized seizure (score: 2). In the CsCl experiments (n=10), the average scores were 1.09 ± 0.10 before administration, 0.82 ± 0.10 during administration, and 0.96 ± 0.10 after administration. CsCl significantly increased the ratio of grade 0 behavioral responses (P<0.01, compared with the value before administration), and decreased the ratio of grade 1 responses (P<0.01). In the ZD7288 experiments (n=19), the average scores were 0.99 ± 0.07 before administration, 0.52 ± 0.06 (P<0.01) during administration, and 0.76 ± 0.07 (P<0.05) after administration. ZD7288 significantly increased the ratio of grade 0 behavioral responses (P<0.01), and decreased the ratio of grade 1 responses (P<0.05) and grade 2 responses (P<0.01). We conclude that both CsCl and ZD7288 have an anti-epileptic effect on inherited epilepsy in Mongolian gerbils.

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We assessed the possibility of C57BL/6-Tg (Meg1/Grb10)isn(Meg1 Tg) mice as a non-obese type 2 diabetes (2DM) animal model. Meg1 Tg mice were born normal, but their weight did not increase as much as normal after weaning and showed about 85% of normal size at 20 weeks of age. Body mass index of Meg1 Tg mice was also smaller than that of control mice. The glucose tolerance test and insulin tolerance test showed that Meg1 Tg mice had reduced ability to normalize the blood glucose level. Blood urea nitrogen (BUN) in Meg1 Tg mice (19.6 ± 1.2 mg/dl) was significantly lower than in controls (22.0 ± 0.8 mg/dl), while plasma triglyceride, insulin, adiponectin, and resistin levels were significantly higher (202.0 ± 23.4 mg/dl vs 146.3 ± 23.4 mg/dl, 152.4 ± 16.3 pg/ml vs 88.1 ± 16.9 pg/ml, 74.4 ± 10.9 μg/ml vs 48.3 ± 7.0 μg/ml, and 4.0 ± 0.2 ng/ml vs 3.6 ± 0.2 ng/ml, respectively). Body, visceral fat weight and liver weights were significantly lower (19.6 ± 0.4 g vs 24.3 ± 0.3 g, 376.7 ± 29.6 mg to 507.5 ± 23.0 mg, and 906.0 ± 41.8 mg to 1,001.0 ± 15.1 mg, respectively). Thus, hyperinsulinemia observed in Meg1 Tg mice indicates that their insulin signaling pathway is somehow inhibited. With high fat diet, the diabetes onset rate of Meg1 Tg mice increased up to 60%. These results suggest that Meg1 Tg mice resemble human 2DM.

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A 2.5 year-old female ferret had a stiff palpable mass arising from the dorsal surface of the thoracic (T) to lumbar (L) vertebrae with paralysis of the hind limbs. By myelography the dorsal and ventral lines of contrast were not observed in the area forwarded of L3. Grossly, the tumor encircled the dorsal vertebrae. Microscopically, tumor cells were proliferated intimately and were attached to the vertebrae surface involving surrounding fatty and connective tissues. The tumor consisted of fibroblastic cells with prominent cellular atypia. The bromodeoxyuridine (BrdU) labeling index to examine cellular kinetics was high (11.8%). Based on macro and micropathological features, the present tumor was diagnosed as periosteal fibrosarcoma arising from perivertebral connective tissue.

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Factors affecting full-term development of rat oocytes after round spermatid injection (ROSI) were examined using fresh and cryopreserved spermatids. Regardless of method (DC pulses or ionomycin) and timing (before or after ROSI) for oocyte activation, similar percentages of oocytes injected with cryopreserved spermatids developed to full-term (3.0-4.8%). In contrast, no offspring were obtained when fresh spermatids were injected into DC-treated oocytes (0%), but a higher proportion of oocytes first injected with fresh spermatids and then activated with ionomycin developed to full-term (6.1%). In further experiment, oocytes activated with ionomycin were injected with frozen-thawed spermatids, and then treated with cycloheximide and/or trichostatin-A. Neither chemical had a beneficial effect on full-term development of ROSI oocytes (3.7-7.9% vs 2.5% in control). In conclusion, regardless of timing of oocyte activation, activation treatment with ionomycin is required for full-term development of rat oocytes injected with fresh spermatids, and the higher potential of cryopreserved spermatids contributing to full-term development is notable when DC pulse is applied for oocyte activation.

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Efficient reproduction using natural mating and reproduction technology [in vitro fertilization (IVF) and embryo transfer (ET)] was investigated in IRS2 deficient mice with C57BL/6JJcl genetic background (Irs2^-/- mice) as a typical type 2 diabetes model. From the results using various combinations of Irs2^-/- and Irs2^-/+ mice, the combination of female Irs2^-/+ × male Irs2^-/- was found to be more efficient than other combinations. In applications of reproduction technology using IVF and ET, the combination of female Irs2^-/+ × male Irs2^-/- involves the possibility of Irs2^-/- production by repeats using female Irs2^-/+ mice. However, reproductive continuity using this combination is difficult because of dependence on human technique and the cost of ET. Therefore, we concluded that Irs2^-/- mice should be produced by embryo transfer using Irs2^-/- mice from a colony consisting of female Irs2^-/+ × male Irs2^-/-.

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Senescence-Accelerated Mouse (SAM) strains are used as animal models for gerontological research. Here, we report that the SAMR1 strain, which shows a high sensitivity to toxicity of the parasiticide ivermectin, has a spontaneous retroviral insertional mutation in the ATP-binding cassette, sub-family B (MDR/TAP), member 1A (Abcb1a) gene. This mutation is identical to that found in Crl:CF1-Abcb1a mice, which are also highly sensitive to ivermectin due to the mutation. The mutant Abcb1a allele was found in SAMR4, SAMR5, SAMP1, SAMP6, SAMP7, and SAMP9, but not in SAMP3, SAMP8, SAMP10, SAMP11, and other outbred and inbred strains, including 129/SvJ strains. These results impart both caution and promise in the use of SAM strains in studies of biological processes in which P-glycoprotein participates.

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Adjuvant-induced arthritic (AIA) rats have been developed as a chronic pain model to evaluate the effects of analgesic drugs. The purpose of the present study was to examine whether there is dose-dependent inhibition of the emission of ultrasonic vocalization (USV) responses by analgesic drugs in AIA rats. It was demonstrated that morphine (1.25-5.0 mg/kg, s.c.) and ketoprofen (2.5-10.0 mg/kg, s.c.) dose-dependently inhibit USV responses. These results suggest that the USV responses elicited in AIA rats are useful for the quantitative evaluation of analgesic drugs.

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