Curcumin is the principal active ingredient found in turmeric (Curcuma longa), a plant used in traditional Asian diets and herbal medicines. It is known to have a wide range of biological actions including antidepressant-like effects which have been observed in stress-induced depression models. This study was designed to investigate the antidepressant potential of curcumin in a non-induced model of depression. Moreover, since brain derived neurotrophic factor (BDNF) has been implicated in antidepressant effects of many drugs, we also evaluated the effects of curcumin on BDNF in the hippocampus. Adult male Wistar Kyoto (WKY) rats, a putative model of depression, were injected acutely or chronically (10d) with 50, 100, and 200mg/kg curcumin. Open field locomotor activity (OFLA) and forced swim test (FST), a measure of helplessness, were measured 1h after acute and 18-20h after last chronic injection. Results showed a dose-dependent reduction of immobility in the FST by curcumin in both acute and chronic studies, without any significant effect on OFLA. The effect of higher chronic curcumin dose in FST was still evident a week later. Chronic curcumin also resulted in a dose-dependent increase in hippocampal BDNF. This data provides evidence for an antidepressant-like effect of curcumin, possibly through increased neurotrophic activity, in the WKY model of depression, and support the notion that curcumin may prove an effective and lasting natural antidepressant.
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