The cyanobacterium Oscillatoria brevis β-carotene extract modulates alterations of biochemical and hematological circadian patterns in stress-induced rat

Managing stress can prevent serious health problems. The present study aimed to evaluate the possible protective effect of β-carotene (βC), as a natural cyanobacterial product, against stress-induced alterations in biochemical and hematological circadian patterns. Male albino rats were subjected to chronic unpredictable stress (CUS) for 21 days. Rats were randomly divided into four groups (20 rats/group), viz. control, CUS exposed, βC-treated, and βC-treated + CUS-exposed groups. Before CUS exposure, Oscillatoria brevis βC extract was administered (10 mg/kg), intraperitoneally. Blood samples were collected at four Zeitgeber times (ZT: 3, 9, 15 and 21), 5 rats/time point, to monitor circadian profiles of aspartate transferase (AST), alanine transferase (ALT), total protein (TP), glucose (Glu), urea, creatinine, lactate dehydrogenase (LDH), creatinine kinase-MB (CK-MB), hemoglobin (Hb), hematocrite (HCV), red blood cell (RBCs), and white blood cell counts (WBCs). Results revealed that these parameters expressed circadian patterns. CUS exposure significantly (p < 0.05) increased AST, ALT, Glu, urea, creatinine, LDH, CK-MB, and HCV. On the other hand, it significantly decreased Hb, RBCs, and WBCs (p < 0.05). Furthermore, under CUS-exposure the peak time (acrophase) of circadian rhythms of all parameters was variably shifted. On the other hand, βC administration modulated these alternations, where data analysis confirmed a significant decrease in AST, ALT, Glu, urea, creatinine, LDH, CK-MB, and HCV, however, a significant increase in TP, Hb, RBCs, and WBCs (p < 0.05) was observed. Taken together, it can be concluded that βC administration caused restoration of acrophase and level of these parameters thus regulating their circadian rhythms in CUS-induced rats.