Omega-3 fatty acids have antidepressant activity in forced swimming test in Wistar rats

Forced swimming test is used to induce a characteristic behavior of immobility in rats, which resembles depression in humans to some extent. We evaluated the effect of omega-3 fatty acids alone as well as compared it with the standard antidepressant therapy with fluoxetine in both acute and chronic studies. In both the studies, rats were divided into 4 groups and subjected to the following drug interventions - Group 1- control: Group 2- fluoxetine in dose of 10 mg/kg subcutaneously 23.5, 5 and 1 h before the test: Group 3- omega-3 fatty acids in dose of 500 mg/kg orally; Group 4- fluoxetine plus omega-3 fatty acids both. In acute study, omega-3 fatty acids were given in single dose 2 h prior to the test while in chronic study omega-3 fatty acids were given daily for a period of 28 days. All animals were subjected to a 15-min pretest followed 24 h later by a 5-min test. A time sampling method was used to score the behavioral activity in each group. The results revealed that in acute study, omega-3 fatty acids do not have any significant effect in forced swimming test. However, in chronic study, omega-3 fatty acids affect the immobility and swimming behavior significantly when compared with control (p < 0.01) without any significant effect on climbing behavior and the efficacy of combination of omega-3 fatty acids and fluoxetine is significantly more than that of fluoxetine alone in changing the behavioral activity of rats in forced swimming test. It leads to the conclusion that omega-3 fatty acids have antidepressant activity per se, and the combination of fluoxetine and omega-3 fatty acids has more antidepressant efficacy than fluoxetine alone in forced swimming test in Wistar rats.