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.

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.