The effect of crocin, exercise and crocin-accompanied exercise on excitability at CA۱ area of hippocampus in chronic unpredicted stressed rats

Background and Aim: Stress causes brain dysfunction in the hippocampus. In addition, crocin as one of active substances of saffron and exercise as an aspect of lifestyle improve memory impairment by stress. Methods: Male rats were randomly allocated to six groups: control, sham, stress, stress-crocin, stress-exercise and stress-crocin-exercise. Dose of ۳۰mg/kg of crocin was injected intraperitoneally for ۲۱ days. The CUS was also applied for ۲ hours/day/for ۲۱ consecutive days. Exercise was performed on a treadmill at a speed of ۲۰-۲۱ m/min with a ۰ degree slope ۱ hour/day/ for ۲۱ days. Extracellular evoked field potentials were recorded from the CA۱ following stimulation of the Schafer pathway. An input-output (I/O) function was obtained by systematic variation of the stimulus current (۱۰۰-۱۰۰۰μA) in order to evaluate excitability at CA۱ area of hippocampus. Results: The present study investigated the effect of crocin, exercise and crocin-accompanied exercise on excitability at CA۱ area of hippocampus in chronic unpredicted stressed (CUS) rats. Conclusion: The slope and amplitude of the input/output curve exhibited significantly (P<۰.۰۰۱ in slope of both group; P<۰.۰۱ in amplitude of both group) differences between the chronic unpredictable stress group (CUS) and stress-exercise group (CUS-Exe) with the control groups, indicating that chronic unpredictable stress and chronic unpredictable stress accompanied with exercise decreased the responsiveness of the CA۱ apical dendritic layer. The slope and amplitude revealed significant enhancements (in slope: P<۰.۰۰۱ and P<۰.۰۱; in amplitude: P<۰.۰۱ and P<۰.۰۵; respectively) in the chronic unpredictable stress- crocin ۳۰ (CUS-C۳۰) and unpredictable stress-crocin۳۰ & exercise (CUS-C۳۰ & Exe) group when compared to the CUS. In the CUS- Exe group, the slope and amplitude were significantly (P<۰.۰۱ and P<۰.۰۵; respectively) different from those of the CUS-C۳۰ group. The slope and amplitude the input/output curve showed significant enhancements (P<۰.۰۱ and P<۰.۰۵, respectively) in the CUS-C۳۰ & Exe group as compared to the CUS- Exe. The results showed that the exercise could not improve the chronic unpredictable stress effects. Whereas, crocin administration improved excitability at CA۱ area of hippocampus in chronic unpredictable stress. Therefore, it seems that herbal plant acts better than exercise on excitability at CA۱ area of hippocampus in chronic unpredictable stress.

کلیدواژه ها:

Unpredictable stress ، Crocin ، I/O ، Exercise ، Rat