We examined mRNA changes of IL-1β, prepro-thyrotropin releasing hormone (TRH), and glucocorticoid receptor (GR) since they are regulated by glucocorticoids and may reflect altered brain function in response to chronic stress. Our goal was to determine if low grade stress repeated daily, alters these markers in limbic areas of the brain involved in maintaining homeostasis. An 8 day stress paradigm that alternated immobilization (15 min) with foot shock (15 min of 0.2 mAmp delivered 15 sec/2.5 min) was employed to reduce predictability of the stress. On day 9, rats were decapitated, trunk blood collected and the amygdala (AMY), hippocampus (HIP) and hypothalamus (HYP) removed and rapidly frozen. There were no differences in plasma levels of ACTH, corticosterone or TSH between stressed and control rats. IL-1β, TRH and GR mRNA levels were determined in the HYP, AMY and HIP by Northern blot analysis using specific cDNA probes. Stressed rats showed a decrease in IL-1β (p<0.01) and TRH (p<0.05) mRNA only in AMY; GR mRNA decreased in AMY and HIP (p<0.05). In comparison there were no significant changes in HYP or HIP in the mRNA level of IL-1β or TRH. This is the first report demonstrating a decease in IL-1β and TRH mRNA in the AMY following repeated stress This response in the limbic system appears to be independent of any change in the hypothalamic-pituitary-adrenal axis. Supported by NIAA Grant #07389-04.
|Original language||English (US)|
|State||Published - Dec 1 1996|
ASJC Scopus subject areas
- Molecular Biology