Effect of Lycopene on Antioxidant Status and Serum Corticosterone in Wistar Rats Subjected to Chronic Mild Stress
Professor, Department of Pharmacology, Sri Ramachandra Institute of Higher Education and Research, Chennai, Tamil Nadu, India.
Introduction: Stress is one of the major causative factors in developing depression. Depression is described as a stress-related disorder which often gets precipitated with chronic stress. Lycopene unlike other carotenoids has the highest antioxidant property and is readily soluble in lipids and crosses the blood-brain barrier, is widely found in fruits and vegetables. Epidemiological data shows that lycopene can prevent and treat various diseases like cardiovascular and neurological disorders. Chronic Mild Stress Method (CMS) is the most valid animal model in inducing depression in rodents. Imbalance in the activities of both oxidant and antioxidants are the important etiological factors in depression. This therapeutic effect can be potential too for various disorders.
Aim: To investigate the possible beneficial effects of lycopene on the antioxidant enzyme activity, serum corticosterone levels and adrenal gland weights in Wistar albino rats subjected to chronic mild stress.
Materials and Methods: The study group consisted of 42-male Wistar rats divided into 7 groups with each group consisting of 6 animals. Control group, CMS group, Vehicle group and Imipramine (10 mg/kg) as a standard drug and lycopene with varying doses of (5, 10, 20 mg/kg) as the test drug. Blood samples were used in estimating serum corticosterone and brain tissues were used in estimating brain antioxidant enzyme activity. Differences in the groups were analysed statistically by one way-ANOVA, followed by post-hoc test was used to find out significant differences between the control and CMS group.
Results: The data analysis showed that CMS could show a significant increase in serum corticosterone levels in the CMS group (only stress) in comparison with the control group (p<0.05). Significant decrease in the levels of SOD, CAT and GSH levels and an increase in the MDA levels were observed in CMS and vehicle-treated group rats. Lycopene supplementary doses of 10 mg/kg and 20 mg/kg administration for 6-weeks significantly improved antioxidant enzyme activity.
Conclusion: The study results, support that chronic mild stress induces oxidative stress in the rodents. There was a decrease in SOD activity and an increase in the serum corticosterone levels and adrenal gland weight in CMS and vehicle groups in comparison to the control groups. Lycopene supplementation reverses this state and shows antidepressant-like activity.