Abstract:

To explore the effect of propranolol on behavior, serum corticosterone level and hippocampal morphology in the chronic unpredictable mild model (CUMS) rats before and after the acute stress. MethodsThirty Wistar male rats were randomly divided into three groups： the control group, CUMS group and propranolol group. The control group was left undisturbed in home cages, while others were exposed to CUMS for 21 days. The propranolol group received perfusion of propranolol and the CUMS group was perfused with normal saline. Then, half of each group were randomly chosen and encountered electric foot shock on day 22. The rats were sacrificed by decapitation two hours after the acute stress. The content of serum corticosterone was evaluated by cortisol radioimmunoassays. And hematoxylineosin staining was used to study morphological changes in the hippocampus. ResultsThe results of openfield test showed that model rats had less locomotor and exploratory activities, and the changes of hippocampal morphology were severe. In contrast to the controls, serum corticosterone in the propranolol group was significantly upregulated before the acute stress, while an obvious decreased level was observed after the novel insult. Moreover, it could not inhibit the morphological changes in the hippocampus.　ConclusionPropranolol could relieve anxiety symptoms in chronic stress, however, it decreased the level of serum corticosterone when animals faced acute stress stimulus.

Key words: Stress， psychological； Behavior； Corticosterone； Hippocampus; Rats, Wistar