Piperine potentiates the protective effects of curcumin against chronic unpredictable stress-induced cognitive impairment and oxidative damage in mice.

Life event stressors are the major vulnerability factors for the development of cognitive disorders. A vital therapeutic for stress related disorders is curcumin, derived from curry spice turmeric. Dietary phytochemicals are currently used as an adjuvant therapy to accelerate their therapeutic efficacy. Therefore, the present study was designed to investigate the effect of curcumin and its co-administration with piperine against chronic unpredictable stress (CUS)-induced cognitive impairment and oxidative stress in mice. Male Laca mice were subjected to undergo a battery of stressors for a period of 28 days. Vehicle/drugs were administered daily 30mins before CUS procedure. Chronic stress significantly impaired memory performance (delayed latency time to reach platform in Morris water maze as well as to reach closed arm in elevated plus maze test) and decreased locomotor activity along with sucrose consumption. Further, there was a significant impairment in oxidative parameters (elevated malondialdehyde, nitrite concentration and decreased reduced glutathione, catalase levels) and mitochondrial enzyme complex activities, along with raised acetylcholinesterase and serum corticosterone levels. Chronic treatment with curcumin (200 and 400mg/kg, p.o.) significantly improved these behavioral and biochemical alterations, restored mitochondrial enzyme complex activities and attenuated increased acetylcholinesterase and serum corticosterone levels. In addition, co-administration of piperine (20mg/kg; p.o.) with curcumin (100 and 200mg/kg, p.o.) significantly elevated the protective effect as compared to their effects alone. The results clearly suggest that piperine enhanced the bioavailability of curcumin and potentiated its protective effects against CUS induced cognitive impairment and associated oxidative damage in mice.