Effects of chronic stress on cognitive functions and anxiety related behaviors in rats

Abstract

The effects of 100 dB prenatal and chronic postnatal white noise stress (WNS) on some cognitive functions and behaviors in rats were investigated. For this purpose, 60 female Sprague-Dawley rats and their 90 male offspring were used. Pregnant rats were divided into Prenatal Stress (PS) and Prenatal Control (PC) groups. WNS was applied to PS group between the 14(th) and 21(st) days of their pregnancy, while PC rats were left undisturbed. After weaning, 40 male pups of PS dams were assigned to prenatal + chronic postnatal stress (PSCS) and prenatal stress + non-stress (PSN) groups. Pups of PC dams were divided into Control (CON) and Corticosterone (CORT) groups. During the postnatal 30(th) and 51(st) days, WNS was applied to PSCS and CORT rats everyday for 45 minutes, while PSN and CON groups were left undisturbed. The effects of stress on adult male offspring were investigated using Morris water maze and defensive withdrawal tests. Blood samples were collected after each test for serum corticosterone measurements. Blood samples of CORT rats were collected before the stress application and at the 1(st), 7(th), 14(th), and 21(st) days of the stress period, immediately after cessation of the stress application. There were no significant differences among groups for learning and behavior tests. Corticosterone levels of CORT rats were significantly higher after the stress period than before stress application. These results indicate that although chronic 100 dB WNS induces a stress response by increasing corticosterone levels, it does not affect cognitive functions and anxiety related behaviors of adult male offspring.