Protective Effect of β-Carotene Extracted From the Cyanobacterium Oscillatoria brevis Against Stress-Induced Alterations of Circadian Behavior and Oxidative Markers rhythms in Rat

Abstract

Health problems related to stress is a major global issue. The present study aims at evaluating the possible protective effect of β-carotene (βC), as a natural cyanobacterial product, against stress-induced alterations in circadian rhythms of behavioral activities and oxidative markers. Male albino rats were subjected to chronic unpredictable stress (CUS) for 21 days. Rats were randomly divided into 4 groups (20 rats/group) viz.; control, CUS-exposed, βC-treated and βC-treated + CUS-exposed groups. One hour before testing, βC extracted from Oscillatoria brevis was administered (10 mg/kg) intraperitoneally (I.P.). Elevated plus maze (EPM) and forced swimming test (FST) were applied for behavioral assessment. Blood samples were collected at four circadian times (CT 3, 9, 15 and 21); 5 rats/time point, to monitor circadian profiles of nitric oxide (NO), lipid peroxidation (LPO) and glutathione (GSH). Circadian patterns were observed in all tested behavioral and antioxidant parameters. CUS induced anxietyand depression-like behavior in rats where the immobility time in FST was significantly increased (P<0.05), whereas the time spent in open arms of EPM was decreased. Data showed that under CUS exposure the peak times (acrophase) of circadian rhythms of NO, LPO and GSH levels as well as immobility time and time spent in open arms were changed. βC improved these changes. CUS significantly increased NO, LPO, while it significantly decreased GSH levels (P<0.05). On the other hand, βC significantly decreased NO, LPO and immobilization time, meanwhile a significant increase of GSH and time spent in open arm was noticed (P<0.05). In conclusion, it can be suggested that βC has an antioxidant and neuroprotective influence in ameliorating both the anti-anxietyand anti-depression-like behavior as well as NO, LPO and GSH levels, in addition to modulating the altered circadian rhythms.