Antidepressant-like Activity of Andrographis paniculata in Type-2 Diabetic Rats

Abstract

Pharmacological observations suggesting antidepressants-like efficacy of a medicinally used Andrographis paniculata extract (AP) in type-2 diabetic are presented in this communication. Efficacies of 10 daily oral doses of 50, 100 and 200 mg/kg/day AP and 15 mg/kg/day imipramine were compared in behavioral despair and learned helplessness tests using type-2 diabetic rats, and bio- and neuro-chemical alterations in the brain tissue of treated animals subjected to learned helplessness test were quantified. Significant imipramine like antidepressant activity of AP was observed even after its lowest daily tested (50 mg/kg/day) in both behavioral tests used, and such efficacy of the extract dose dependently increased with its increasing dose. Imipramine like effects of AP in elevating lower hippocampal levels of norepinephrine, dopamine, and serotonin observed in diabetic rats towards normal values were also observed after its 50 mg/kg/day doses and such efficacy of the extract increased also with its increasing daily doses. Levels of all the three monoamines quantified in 100 mg/kg/day AP treated diabetic rats were significantly higher than those of the non-diabetic animals. Imipramine had no significant effects on body weight losses, hyperglycemia, insulin deficiency, lower catalase and superoxide dismutase activities and higher lipid peroxides in the frontal cortex, and mitochondrial monoamine oxidase activities observed in diabetic animals. All such quantified biochemical and other pathologies observed in diabetic were significantly antagonized even by 50 mg/kg daily oral doses of AP, and its efficacies always increased with its increasing daily doses. These observations strongly suggest that AP could be an herbal alternative for treatments of diabesity-associated depression resistant to imipramine like antidepressants, and that antidepressants like efficacy of the extract is most probably due to its inhibitory effects on brain mitochondrial monoamine oxidase activities. The observed beneficial of AP on brain oxidative status could be indicative of its neuro-protective potentials as well. In any case its minimal effective doses for all such efficacies should be below or around 50 mg/kg/day.