Increased 5-HT Levels Following Repeated Administration of Nigella sativa L. (Black Seed) Oil Produce Antidepressant Effects in Rats

The seeds of Nigella sativa L., commonly known as black seed or black cumin, and its extracts are used in folk medicine in the Middle East and in Asian countries for the promotion of good health and as a remedy for many ailments. These seeds have many acclaimed medicinal properties such as broncho-dilatory, immunopotentiating, analgesic, anti-inflammatory, and hypotensive. In the present study, the antidepressant activity following the repeated administration of Nigella sativa L. oil has been monitored using the forced swim test. Rats treated with Nigella sativa L. oil exhibited a significant increase in struggling time after oral administration of Nigella sativa L. oil (0.1 ml/kg/day) for four weeks. Nigella sativa L. oil increased brain 5-HT levels and decreased 5-HT turnover (5-HT/5-HIAA ratio). Levels of tryptophan increased significantly in the brain and plasma following the repeated administration of Nigella sativa L. oil. Nigella sativa L. oil showed a potential antidepressant-like effect.