Antidepressant-like Effects of Intra-cerebroventricular Microinjection of Kaempferol in Male Rats: Involvement of 5-HT2 Receptors

Background and Objective: Kaempferol (KM) is a flavonoid found in plant-derived foods and medicinal plants. Recently, it has been well established that KM plays a protective role against the development of Alzheimer's disease. This study evaluated the effect of intracerebroventricular microinjection of KM on depression and identified the potentially related serotonergic mechanisms in rats. Materials and Methods: Male rats were assigned to control, vehicle (dimethyl sulfoxide), KM, fluoxetine, cyproheptadine, KM (20 mg/rat) + cyproheptadine (1 mg/rat), and KM (20 mg/rat) + cyproheptadine (4 mg/rat) groups. All the groups received their respective treatments for 30 days. Depression was evaluated by both forced swimming and tail suspension tests. Monoamine oxidase-A (MAO-A), as a neurochemical parameter, was also evaluated in the liver and brain of animals. Results: Treatment with KM significantly decreased immobility time in both forced swimming and tail suspension tests, compared to the vehicle. In the forced swimming test, remarkable effects in immobility time were induced by KM + cyproheptadine after a single dose during weeks 2, 3, and 4 of treatment, compared to the cyproheptadine group. In the tail suspension test, both fluoxetine and KM indicated remarkable effects in the immobility time during weeks 3 and 4. In addition, in both the brain and liver, MAO-A activity was decreased after treatment with KM. Conclusions: These results indicated the antidepressant-like effects of KM through the involvement of 5HT2 receptors in male rats.