Transcription profiling of brains from rats exposed to cold stress vs. controls

Stress leads to important adaptive physiological responses including release of catecholamines from the adrenal medulla. Repeated or prolonged stress increases the propensity for many disorders including cardiovascular disease and neuropsychiatric disorders. The susceptibility to stress is determined by a number of factors including prior experience with stress. It has been found that while there is adaptation to prolonged cold stress; it leads to sensitization when cold stressed animals are exposed to a different (novel) stressor. Our study aims to determine the mechanism of this adaptation and sensitization.,We will determine the gene expression patterns in rat adrenal medulla in response to several times of cold stress. We will also determine the changes in gene expression with single immobilization stress in adrenal medulla of rat with and without preexposure to cold stress to investigate the mechanism of sensitization in cold adapted animals. ,We hypothesize that during the course of cold stress there are alterations in gene expression of several neurotransmitter related genes and transcription factors. In cold adapted animals, there is increased susceptibility to stress due to sustained changes in expression of several transcription factors, such as FRA-2 which lead to an exaggerated response to the novel stressor. ,Rats were exposed to cold stress (4oC) for 1, 7 or 28 days. A parallel group was kept at room temperature (unstressed). Unstressed or rats pre-exposed to 28 days cold were immobilized for 2 hrs and killed by decapitation. The adrenal medullae, separately from right and left side, have been dissected and individually frozen at -70oC. Our recent immunoblots with the tissue from one side revealed that there is increase in tyrosine hydroxylase and c-fos with the short term cold stress and in dopamine beta hydroxylase and Fra-2 even with the prolonged cold stress. The response of several transcription factors to immobilization stress was enhanced in the cold adapted animals. RNA will be prepared with RNAqueous-Micro Isolation kit from Ambion (alternatively we can ship the tissues). We will pool samples from 4 rats per treatment to control for variability.