Noise Stress-Induced Changes in mRNA Levels of Corticotropin-Releasing Hormone Family Molecules and Glucocorticoid Receptors in the Rat Brain

Abstract

Noise is a widespread stress resource that may lead to detrimental effects on the health. However, the molecular basis of the stress response caused by noise remains elusive. We have studied the effects of acute and chronic noise stress on stress-related molecules in the hypothalamus and hippocampus and also corticosterone responses. Sprague Dawley rats were randomized into control, acute and chronic noise stress groups. While the chronic noise stress group animals were exposed to 100 dB white noise for 4 h/a day during 30 days, the acute noise stress group of animals was exposed to the same level of stress once for 4 h. The expression profiles of corticotropin-releasing hormone (CRH), CRH1, CRH2 receptors and glucocorticoid receptor (GR) mRNAs were analysed by RT-PCR. Chronic noise stress up-regulated CRH mRNA levels in the hypothalamus. Both acute and chronic noise increased CRH-R1 mRNA in the hypothalamus but decreased it in the hippocampus. GR mRNA levels were decreased by chronic noise stress in the hippocampus. The present results suggest that while corticosterone responses have habituated to continuous noise stress, the involvement of CRH family molecules and glucocorticoid receptors in the noise stress responses are different and structure specific.