Experimental Animals (EXP ANIM TOKYO)

Publications in this journal

• Article: Genetic marker patterns and endogenous tumor viral genes in inbred mouse strains of Japan

  S Imai, J Morimoto, Y Tsubura, K Evaki, R Michalides, RS Holmes, O von Deimling and J Hilgers
  Experimental Animals 02/2013; 35:263-273.
• Article: Different locomotor activities and monoamine levels in the brains of Djungarian hamsters (D. sungorus) and Roborovskii hamsters (D. roborovskii).

  Yusuke Kabuki, Haruka Yamane, Kousuke Hamasu, Mitsuhiro Furuse
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  ABSTRACT: Two species of the genus Phodopus, Djungarian hamster (P. sungorus) and Roborovskii hamster (P. roborovskii), differ in their behavior. The Roborovskii hamster has high locomotor activity (hyperactivity) compared to the Djungarian hamster. In this study, we compared locomotor activity of the hamsters in different environments, and compared their brain monoamine and metabolite levels to identify the mechanism by which both hamsters move differently. Activity of Roborovskii hamsters was significantly higher than Djungarian hamsters in the open field, while no difference was observed in their home cage. Dopamine (DA) and serotonin (5-HT) levels in the whole brain of Roborovskii hamster were significantly lower and their metabolic turnover rates were significantly higher than those of the Djungarian hamster. We conclude that the difference in activity under the novel environment between both species is partly, but not entirely, explained by the difference in monoamine levels and their metabolism in the brain.
  Experimental Animals 11/2008; 57(5):447-52.
• Article: Pioglitazone improves obesity type diabetic nephropathy: relation to the mitigation of renal oxidative reaction.

  Yasushi Hirasawa, Yukari Matsui, Kazusuke Yamane, Shin-Ya Yabuki, Yukiko Kawasaki, Tohru Toyoshi, Kohei Kyuki, Masanori Ito, Takayuki Sakai, Tadashi Nagamatsu
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  ABSTRACT: Medications to treat hyperglycemia and hyperinsulinemia are expected to inhibit the accumulation of advanced glycation end-products in the diabetic kidney and improve renal function by inhibiting oxidative reactions. In this study, we examined the effect of pioglitazone, an insulin sensitizer, on diabetic nephropathy. Feed containing pioglitazone at 0.01 or 0.02% was given to Zucker-fatty rats for 27 weeks. Pioglitazone reduced plasma glucose, plasma insulin, and blood HbAlc levels. It also decreased plasma total cholesterol, triglyceride, phospholipid and cystatin C levels and inhibited the increase in urine of 8-hydroxydeoxyguanosine and in plasma of malondialdehyde. In the histopathological examinations, pioglitazone inhibited diffusive or nodular thickening of the mesangial matrix, atrophy of the proximal convoluted tubule, thickening of the basement membrane of the tubule, and mild cellular infiltration (mostly small lymphocytes) in the stroma. Furthermore, pioglitazone inhibited the mRNA expression of the receptor for advanced glycation end-products (RAGE) and that of transforming growth factor-beta. Long-term administration of pioglitazone improved hyperglycemia lipid profiles, hypercholesterolemia, and hyperinsulinemia and had a protective effect on diabetic nephropathy in Zucker-fatty rats.
  Experimental Animals 11/2008; 57(5):423-32.
• Article: Correlation between body weight (epididymal fat) and permeation rate of serum leptin through the blood-brain barrier (BBB) in male rats aged 8 months.

  Mitsuro Suzuki, Qing Ding, Shiro Muranaka, Megumi Kigure, Masaaki Kojima, Misao Terada, Noyuri Kataoka, Akiko Hagiwara, Pudcharaporn Kromkhun, Naoki Moritani, Haruo Hashimoto, Makoto Yokosuka, Fujiro Sakurai, Minoru Tanaka, Toru R Saito
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  ABSTRACT: In this study, in order to clarify the kinetics of leptin, we focused on the ratio of leptin concentrations in cerebrospinal fluid and serum in aged male rats, and examined the weight of epididymal fat, and the passage rate of leptin through the blood-brain barrier. In the lighter animals, the epididymal fat weight was low, while leptin concentrations in the serum and cerebrospinal fluid were also low. Conversely, in the heavier animals, the weight of epididymal fat and leptin concentrations in the serum and cerebrospinal fluid were higher. With regard to the ratio of leptin in the cerebrospinal fluid and serum, the passage rate of leptin through the blood-brain barrier was lower in the heavier animals than in the lighter animals.
  Experimental Animals 11/2008; 57(5):485-8.
• Article: Changes in food intake and abnormal behavior using a puzzle feeder in newly acquired sub-adult rhesus monkeys (Macaca mulatta): a short term study.

  Jae-Il Lee, Chi-Woo Lee, Hyouk-Sang Kwon, Young-Tae Kim, Chung-Gyu Park, Sang-Joon Kim, Byeong-Cheol Kang
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  ABSTRACT: The majority of newly acquired nonhuman primates encounter serious problems adapting themselves to new environments or facilities. In particular, loss of appetite and abnormal behavior can occur in response to environmental stresses. These adaptation abnormalities can ultimately have an affect on the animal's growth and well-being. In this study, we evaluated the affects of a puzzle feeder on the food intake and abnormal behavior of newly acquired rhesus monkeys for a short period. The puzzle feeder was applied to 47- to 58-month-old animals that had never previously encountered one. We found that there was no difference in the change of food intake between the bucket condition and the puzzle feeder condition. In contrast, the time spent for consumption of food was three times longer in the puzzle feeder condition than in the bucket condition. Two monkeys initially exhibited stereotypic behavior. One showed a decreasing, and the other an increasing pattern of abnormal behavior after introduction of the puzzle feeder. In conclusion, this result suggests that over a short period, the puzzle feeder can only affect the time for food consumption since it failed to affect the food intake and did not consistently influence stereotypic behaviors in newly acquired rhesus monkeys.
  Experimental Animals 11/2008; 57(5):433-7.
• Article: The effects of BADGE and caffeine on the time-course response of adiponectin and lipid oxidative enzymes in high fat diet-fed C57BL/6J mice: correlation with reduced adiposity and steatosis.

  Jun-Won Yun, Eui-Seok Shin, Si-Young Cho, Shin-Hyoung Kim, Chae-Wook Kim, Tae-Ryong Lee, Bae-Hwan Kim
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  ABSTRACT: Adiponectin, which is expressed exclusively in adipose tissue, has been shown to increase fatty acid oxidation via activation of AMP-activated kinase (AMPK) and phosphorylation of acetyl CoA carboxylase (ACC). ACC phosphorylation and carnitine palmitoyl-transferase-1 (CPT1) activity have been shown to be rate controlling factors in fatty acid oxidation. In high fat diet (HFD)-induced obese mice, we analyzed the time-course of changes in the expression of adiponectin and lipid oxidative enzymes induced by treatment with bisphenol A diglycidyl ether (BADGE) or caffeine for 8 weeks, and investigated whether the changes of adiponectin and lipid oxidative enzymes expression correlated with reduced adiposity or steatosis after 8 weeks of treatment. After 8 weeks of treatment, BADGE and caffeine had reduced body weight and epididymal adipose tissue weight in mice fed HFD, and markedly reduced the number of fatty droplets in the liver. Interestingly, the expression of adiponectin and lipid oxidative enzymes significantly increased after 2 weeks of treatment. These results indicate that the expression of adiponectin and lipid oxidative enzymes in the early stages of BADGE or caffeine treatment correlated well with the long-term anti-obesity effects.
  Experimental Animals 11/2008; 57(5):461-9.
• Article: Establishing EGFP congenic mice in a NOD/Shi-scid IL2Rg(null) (NOG) genetic background using a marker-assisted selection protocol (MASP).

  Hiroshi Suemizu, Chie Yagihashi, Tomoko Mizushima, Tomoyuki Ogura, Tomoo Etoh, Kenji Kawai, Mamoru Ito
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  ABSTRACT: Severely immunocompromised NOD/Shi-scid IL2Rg (null) (NOG) mice, which show higher engraftment efficiency, are useful as recipients in xenotransplantation studies. We generated a NOG-enhanced green fluorescent protein (EGFP) transgenic (Tg) mouse (NOG-EGFP) that was introduced the EGFP transgene from the C57BL/6-EGFP Tg mouse using the speed congenic method with a marker-assisted selection protocol (MASP). With this method, the selection of the male with the closest NOG strain type was repeated four times. When human cord blood CD34(+) cells were transplanted into NOD/Shi-scid, NOG, and NOG-EGFP mice (N(6)), the engraftment efficiency of the NOG-EGFP mice was significantly higher than that of the NOD/Shi- scid mice and was similar to that of the NOG mice. These results suggest that the NOG-EGFP mice, which were generated using the congenic method with MASP, acquired the immunological properties of the NOG mice.
  Experimental Animals 11/2008; 57(5):471-7.
• Article: Gender difference in the composition of fecal flora in laboratory mice, as detected by denaturing gradient gel electrophoresis (DGGE).

  Seigo Fushuku, Koichi Fukuda
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  ABSTRACT: The difference between genders in the composition of mouse fecal flora was examined. A polymerase chain reaction followed by denaturing gradient gel electrophoresis (DGGE) were performed on the V6-V8 regions of bacterial 16S rDNA obtained from fecal samples at 0, 1, 2, 3, 4, and 8 weeks after the introduction of mice into the laboratory from a mouse farm. Cluster analysis and non-metric multidimensional scaling (NMDS) were then performed. Male and female mice were distributed on opposite sides of the origin of the plane in NMDS at weeks 0, 2, 3, and 8. These results suggest a gender difference in the composition of intestinal flora in mice.
  Experimental Animals 11/2008; 57(5):489-93.
• Article: Maternal environment alters social interactive traits but not open-field behavior in Fischer 344 rats.

  Yutaka Yamamuro
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  ABSTRACT: Although it is recognized that the genetic background governs behavioral phenotypes, environmental factors also play a critical role in the development of various behavioral processes. The maternal environment has a major impact on pups, and the cross-fostering procedure is used to determine the influence of early life experiences. The present study examined the influence of maternal environment on behavioral traits in inbred Fischer 344 (F344) rats. F344/DuCrlCrlj and Wistar (Crlj:WI) pups were fostered from postnatal day 1 as follows: Wistar pups raised by Wistar dams, F344 raised by Wistar, Wistar raised by F344, and F344 raised by F344. At 10 weeks of age, rats were randomly assigned to an open-field test and social interaction test. In the open-field test, irrespective of the rearing conditions, the activity during the first 1 min was significantly lower in F344 rats than in Wistar rats. Latency to the onset of movement showed no difference between groups. In the social interaction test, the recognition performance during the first 1 min in F344 raised by F344 was significantly shorter than that in the other groups. The onset of recognition to a novel social partner in F344 raised by F344 was significantly delayed, and the delay disappeared upon cross-fostering by Wistar dams. These results raise the possibility that the behavioral phenotype of F344 rats results from the interplay of genetic factors and maternal environment during early life, and that F344 rats are a strain with high susceptibility to rearing conditions for the formation of their emotionality.
  Experimental Animals 11/2008; 57(5):439-46.
• Article: Hyperlipidemia in rabbit hemorrhagic disease.

  Sheng-Yi Chen, Jui-Hung Shien, Hong-Kean Ooi
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  ABSTRACT: Clinically healthy rabbits were inoculated with rabbit hemorrhagic disease virus (RHDV) and the kinetics of their serum lipid parameters and liver enzymes were monitored. After RHDV inoculation, hyperlipidemia was observed (P(triglyceride)<0.0001, P(cholesterol)=0.0003) along with significant increases in serum aspartate aminotransferase, alanine aminotransferase and gamma-glutamyltransferase (P<0.0001). An exponential increase in serum triglyceride was also seen. Thus, the presence of hyperlipidemia (from 30 h post-inoculation) in the infected rabbits points to impairment in lipid metabolism. This is the first demonstration that RHDV infection leads to hyperlipidemia, probably due to the disorder of liver enzymes associated with lipid metabolism.
  Experimental Animals 10/2008; 57(5):479-83.
• Article: Serological evidence for hepatitis e virus infection in laboratory monkeys and pigs in animal facilities in Japan.

  Hiroshi Yamamoto, Tian-Cheng Li, Chihiro Koshimoto, Kaori Ito, Masakazu Kita, Nobumoto Miyashita, Jiro Arikawa, Kenichi Yagami, Masahide Asano, Hideo Tezuka, Noboru Suzuki, Tsutomu Kurosawa, Toshiyuki Shibahara, Masato Furuya, Shirou Mohri, Hiroshi Sato, Kazutaka Ohsawa, Kentaro Ibuki, Naokazu Takeda
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  ABSTRACT: 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.
  Experimental Animals 07/2008; 57(4):367-76.
• Article: Type 2 diabetes mellitus in a non-obese mouse model induced by Meg1/Grb10 overexpression.

  Yoshie Yamamoto, Fumitoshi Ishino, Tomoko Kaneko-Ishino, Hirosuke Shiura, Kozue Uchio-Yamada, Junichiro Matsuda, Osamu Suzuki, Katsunori Sato
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  ABSTRACT: 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 microg/ml vs 48.3 +/- 7.0 microg/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.
  Experimental Animals 07/2008; 57(4):385-95.
• Article: Factors affecting full-term development of rat oocytes microinjected with fresh or cryopreserved round spermatids.

  Masumi Hirabayashi, Megumi Kato, Shinichi Hochi
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  ABSTRACT: 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.
  Experimental Animals 07/2008; 57(4):401-5.
• Article: Effects of the Ih blockers CsCl and ZD7288 on inherited epilepsy in Mongolian gerbils.

  Yoshiki Matsuda, Nobuko Saito, Kiyofumi Yamamoto, Takashi Niitsu, Shinichi Kogure
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  ABSTRACT: 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.
  Experimental Animals 07/2008; 57(4):377-84.
• Article: Detection of the antibody to lymphocytic choriomeningitis virus in sera of laboratory rodents infected with viruses of laboratory and newly isolated strains by ELISA using purified recombinant nucleoprotein.

  Kazuhiro Takimoto, Motoko Taharaguchi, Shigeru Morikawa, Fumio Ike, Yasuko K Yamada
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  ABSTRACT: 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.
  Experimental Animals 07/2008; 57(4):357-65.
• Article: Quantitative analysis of the ultrasonic vocalization responses elicited in adjuvant-induced arthritic rats for screening analgesic drugs.

  Hiroyuki Naito, Maki Inoue
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  ABSTRACT: 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.
  Experimental Animals 07/2008; 57(4):419-22.
• Article: Characterization of STZ-Induced Type 2 Diabetes in Zucker Fatty Rats.

  Takashi Okamoto, Naohide Kanemoto, Yutaka Ohbuchi, Mai Okano, Hiroyuki Fukui, Toshiki Sudo
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  ABSTRACT: 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.
  Experimental Animals 07/2008; 57(4):335-45.
• Article: A case of fibrosarcoma on the perivertebral surface of a ferret with hind limb paralysis.

  George Ohta, Masato Kobayshi, Tokuma Yanai, Hiroki Sakai, Masashi Yuki, Toshiaki Masegi
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  ABSTRACT: 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.
  Experimental Animals 07/2008; 57(4):397-400.
• Article: Senescence-Accelerated Mouse (SAM) strains have a spontaneous mutation in the Abcb1a gene.

  Guohong Zhang, Beiru Zhang, Xiaoying Fu, Hiroshi Tomozawa, Kiyoshi Matsumoto, Keiichi Higuchi, Masayuki Mori
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  ABSTRACT: 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.
  Experimental Animals 07/2008; 57(4):413-7.