Effects of stress on CRH, CRH‐R1, CRH‐R2 expressions and anxiety‐related behaviors (728.16)

Abstract

The effects of noise stress on brain corticotrophin‐releasing hormone (CRH), CRH receptors 1and 2 (CRH‐R1, CRH‐R2) mRNA levels and anxiety related behaviors in rats have been investigated.Rats, which were divided into 4 groups consisting of 8 animals each, were used for gene expression analyses. Basal Level Group (BSG) was sacrificed without exposing to stress. Other groups were exposed to 4 hour long, 100 dB white noise stress every day. Acute Stress Group (ASG) was sacrificed after 30 min stress application. Subacute Stress Group (SSG) and Chronic Stress Group (KSG) were sacrificed at day 16 and at day 31 respectively, 24 hours after stress application. Expression profiles of CRH, CRH‐R1, and CRH‐R2 in amygdala and hypothalamus were analysed by quantitative RT‐ PCR.The same stress procedure was applied to the experimental group of behavior test. Effects of stress on anxiety‐related behaviors were investigated in defensive withdrawal test. Control and experimental rats were tested on 29th and 30th of the stress application days.CRH and CRH‐R1 mRNA levels increased in amygdala and hypothalamus of KSG animals comparing to those of control. In amygdala mRNA levels of CRH‐R1 in ASG animals and CRH‐R2 in ASG, SSG and KSG decreased. In hypothalamus, CRH‐R2 mRNA levels in SSG decreased. In the defensive withdrawal test, latency to exit the closed chamber decreased in stressed group.Chronic white noise stress causes delayed CRF system activation observed as CRH and CRH‐R1 mRNA expression increases in brain . As anxiety related behaviors were measured before this delayed activation, anxiolytic effect observed in stressed animals may be related to decreased CRH‐R2 mRNA levels in amygdala and also the type of the stressor.Grant Funding Source: This work was supported by Research Fund of Istanbul University (No:4963)