EFFECTS OF PIPERINE ON COGNITIVE FUNCTION AND KEY ENZYMES RELEVANT TO NEURODEGENERATION IN RATS

Abstract

Piperine (PIP) is a major alkaloid present in fruits and roots of pepper species, which are used as food and of great medicinal importance in folklore medicine. The present study assessed the effects of piperine (PIP) on spatial memory and key enzymes [acetylcholinesterase (AChE), butyrylcholinesterase (BChE), monoamine oxidase (MAO), ectonucleoside triphosphate diphosphohydrolase (NTPDases), 5’-nucleotidase (5’NT) and adenosine deaminase, ADA)] linked to neurodegeneration. Scopolamine was used to induce an Alzheimer’s disease (AD)-like model in rats. Forty male Wistar rats were randomly divided into eight groups: normal control rats (NC), scopolamine induced AD (SCO), scopolamine induced AD plus piperine 5 mg/kg (SCO + PIP 5mg), scopolamine induced AD plus piperine 10 mg/kg (SCO + PIP 10mg), scopolamine induced AD plus prostigmine 1mg/kg (SCO + PS), piperine 5 mg/kg (PIP 5mg), Piperine 10mg/kg kg (PIP 10mg), prostigmine 1 mg/kg (PS). A single dose of intraperitoneal injection of scopolamine (2mg/kg) was administered on the 14th day prior to the termination of the experiment. Oral administration of piperine once daily for 14 days was done throughout the experiment. Prior to sacrifice of the animals, memory test using the Y maze was carried out. The results revealed that piperine inhibited AChE, BChE and MAO activities in concentration dependent manner in vitro. Furthermore, oral administration of piperine prevented scopolamine-induced memory impairment, and modulated the activities of AChE, BChE, MAO, NTPDases, 5’NT and ADA in hippocampus, cerebral cortex, cerebellum of the brain and in the plasma. The inhibitory effect of piperine on key enzymes relevant to neurodegeneration may explain, in part, the protective effect of piperine on ameliorating the progression of neurodegenerative diseases including Alzheimer’s disease. Therefore, piperine may act as a potential neuroprotective agent.