Chronic and Acute Stress Interrelationship: Corticosterone Response

Abstract

Male Wistar rats weighing 200-300 g were used. The rats were housed in a temperature and light controlled environment and received water and food "ad libitum". Chronic stress was provoked with an alarm bell and intermittent light applied 1 hour/day during 20 days and a dog was used to provoke acute stress. A modification of Stahl, Hertling and Knappe's (1963) fluorimetric method was used to analyze corticosterone; in order to confirm the specificity of the results some samples were analyzed either by direct radioimmunoassay or after having been previously purified by paper chromatography. Results and DiscussionAs can be seen in Fig. 1 the dynamic of seric corticosterone response to the presence of a dog differed in the rats submitted to chronic (sound and light) stress (group II) compared with the nonpreviously stressed rats (group I). The initial response to a new stress was slower in group II (p < 0.05 respect to the control) than in group I (p < 0.05 respect to the control), but there was no significant statistical difference at 20-60 min after the stimulus.