Effects of air transportation cause physiological and biochemical changes indicative of stress leading to regulation of chaperone expression levels and corticosterone concentration.

Laboratory animals generally experience numerous unfamiliar environmental and psychological influences such as noises, temperatures, handling, shaking, and smells during the process of air transportation. To investigate whether stress induced by air transportation affects stress-related factors in animals, the levels of hormone and chaperone protein were measured in several tissues of F344 rats transported for 13 h and not transported. Herein, we conclude that the levels of corticosterone, HSP70, and GRP78 were significantly increased in the transported group compare to not transported group, but they were rapidly restored to the not transported group level after a recovery period of one week. However, the magnitude of induction and restoration levels of these factors varied depending on the tissue type. Thus, these results suggest that air transportation should be considered for the improvement of laboratory animal health and to reduce the incidence of laboratory animal stress.

Microarray analysis of insulin-regulated gene expression in the liver: the use of transgenic mice co-expressing insulin-siRNA and human IDE as an animal model.

To characterize the changes in global gene expression in the livers of H1/siRNAinsulin-CMV/hIDE transgenic (Tg) mice in response to the reduced bioavailability of insulin, total RNA extracted from the livers of 20-week-old Tg and non-Tg mice was converted to cDNA, labeled with biotin and hybridized to oligonucleotide microarrays. The microarray results were confirmed by a real-time reverse transcription-polymerase chain reaction. Two hundred and fifty-one and 73 genes were up- and down-regulated, respectively by insulin in H1/siRNAinsulin-CMV/hIDE Tg mice compared to the controls. Genes encoding for physiological processes, extracellular defense response and response to biotic stimuli were significantly over-represented in the up-regulated group. Among the down-regulated transcripts, those encoding for extracellular matrix proteins were dramatically over-represented, followed by those related to monooxygenase and oxidoreductase activities. The major genes in the up-regulated categories included Egr1, Saa2, Atf3, DNAJB1 and cCL2, whereas those in the down-regulated categories were Cyp17a1, Adn, Gadd45g, Eno3 and Moxd1. These results indicate that the microarray analysis identifies several gene functional groups and individual genes that respond to a sustained reduction in the insulin levels in the livers of Tg mice. These results also suggest that microarray testing is a useful tool for the better understanding of insulin-regulated diabetes-related diseases.

Selenium acts as an insulin-like molecule for the down-regulation of diabetic symptoms via endoplasmic reticulum stress and insulin signalling proteins in diabetes-induced non-obese diabetic mice.

To investigate whether selenium (Sel) treatment would impact on the onset of diabetes,we examined serum biochemical components including glucose and insulin,endoplasmic reticulum (ER) stress and insulin signalling proteins, hepatic C/EBP-homologous protein (CHOP) expression and DNA fragmentation in diabetic and non- diabetic conditions of non-obese diabetic (NOD) mice. We conclude that (i) Sel treatment induced insulin-like effects in lowering serum glucose level in Sel-treated NOD mice, (ii) Sel-treated mice had significantly decreased serum biochemical components associated with liver damage and lipid metabolism, (iii) Sel treatment led to the activation of the ER stress signal through the phosphorylation of JNK and eIF2 protein and insulin signal mechanisms through the phosphorylation of Akt and PI3 kinase, and (iv) Sel-treated mice were significantly relieved apoptosis of liver tissues indicated by DNA fragmentation assay in the diabetic NOD group. These results suggest that Sel compounds not only serve as insulin-like molecules for the downregulation of glucose level and the incidence of liver damage, but may also have the potential for the development of new drugs for the relief of diabetes by activating the ER stress and insulin signalling pathways.

Significant change in insulin production, glucose tolerance and ER stress signaling in transgenic mice coexpressing insulin-siRNA and human IDE.

The dual expression system for the suppression and clearance of insulin has not been previously used to produce transgenic mice for diabetes-related disease. The aim of this study was to produce new transgenic mice coexpressing specific insulin small interfering RNA (siRNA) sequences and the human insulin degrading enzyme (hIDE) gene in order to examine the diabetes-like phenotype. To achieve this, a new lineage of transgenic mice was produced by the microinjection of the dual expression constructs (pH1/siRNAinsulin-CMV/hIDE) into mouse fertilized eggs. The results showed that overexpressing the insulin siRNA and hIDE genes resulted in the induction of the human enzyme, impaired glucose tolerance and lower serum insulin levels compared to the Non-Tg mice. Moreover, the Tg mice aged 20 weeks had a significantly activated ER stress signaling compared to their Non-Tg counterparts, which may be associated with the suppression of insulin production in the pancreas and the degradation of insulin in the liver, respectively. Therefore, insulin-suppressed transgenic mice can be used to examine diabetes as a new diabetes-like phenotype model, which results in a lower level of circulating insulin without the destruction of pancreatic islets.

Microbiological monitoring of guinea pigs reared conventionally at two breeding facilities in Korea.

In this study, microbiological monitoring of guinea pigs reared conventionally in two facilities was performed twice in 2004, with a three-month-interval between surveys. This study was based on the recommendations of the FELASA Working Group, with some modifications. In serological tests in the first survey, some animals from facility A showed positive results for Encephalitozoon cuniculi, Sendai virus, pneumonia virus of mice (PVM), and Reovirus-3 (Reo-3); facility B showed a positive result only for E. cuniculi. The results of the second survey were similar to the first, except for the presence of Sendai virus; all animals from the two facilities were Sendai virus-negative in the second experiment. No pathogenic bacteria were cultured in the organs of any of the animals in the first survey. However, in the second survey, Bordetella bronchiseptica was cultured from the lung tissue of two 10-week-old animals from facility A. Chlamydial infection was examined by the Macchiavello method, but no animal showed positive results. Tests using fecal flotation or the KOH wet mount method showed no infection of endoparasites, protozoa, ectoparasites, or dermatophytes in any animal in both surveys. However, in the histopathological examination, an infection of protozoa-like organisms was observed in the cecum of some animals from facility A. The present study revealed that microbiological contamination was present in guinea pigs reared conventionally in two facilities in Korea, suggesting that there is a need to improve environmental conditions in order to eradicate microbial contamination.

Physiological difference between dietary obesity-susceptible and obesity-resistant Sprague Dawley rats in response to moderate high fat diet.

The primary aim of the present study was to define central and peripheral physiological differences between dietary obesity-susceptible (DOS) and obesity-resistant (DOR) outbred Sprague Dawley (SD) rats when given a moderate high fat diet containing 32.34% of energy as a fat. After a 9-week feeding period, the DOS-SD rats consumed significantly more feed (11.1%) and had higher abdominal (39.9%) and epididymal (27.5%) fat pads than the DOR-SD rats. In addition, serum leptin and insulin levels were significantly increased in the DOS-SD rats compared with those in the DOR-SD rats. However, we did not observe significant differences in serum triglyceride, cholesterol and glucose. No differences in hypothalamic OB-Ra and Rb mRNA expressions were found between the two groups. In contrast, arcuate NPY immunohistochemical expression was much higher in the DOS-SD rats than in the DOR-SD rats, though NPY expression in the supraoptic and paraventricular nuclei was not different between the two phenotypes. In peripheral tissues, the DOS-SD rats showed noticeably increased acetyl CoA carboxylase (ACC) mRNA expression in the liver, not epididymal fat. However, Western blot of peroxisomal proliferator activated factor gamma (PPAR gamma) in the liver and epididymal fat was not different between the two phenotypes of SD rats. It was concluded that different body weight phenotypes within outbred SD population responded differently to the development of dietary induced obesity via altered anabolic features in the hypothalamus and liver.