Effects of Piperine Pretreatment on Antioxidant Capacity and Spatial Memory Impairment Induced by Local Injection of Lysolecethin in Rat Hippocampus

Background and purpose: Piperine as the main alkaloid of black pepper has antioxidant and neuroprotective properties, so, it is an appropriate candidate to be studied in animal models of multiple sclerosis. This research aimed at investigating the effect of pretreatment with piperine on spatial memory, oxidative stress, and myelin repair gene markers in local demyelination model. Materials and methods: Adult male Wistar rats (200–220 g) were studied in four experimental groups (n=8 per group). Demyelination was induced by bilateral injection of lysolecithin (LPC) into the CA1 region of the hippocampus. Piperine was injected intraperitoneally at 5 mg/kg for two weeks before induction of demyelination until the end of the experiment. The effect of piperine on spatial memory was assessed by Morris water maze. The gene expression analysis on iNOS, Nrf2, HO1, and MBP was done using qPCR. Total antioxidant capacity in the hippocampal tissue was measured by FRAP biochemical assay. Results: Pretreatment with piperine significantly reduced escape latency and swimming distance and increased time spent in target quadrant in Morris water maze test (P<0.0001) . In the Piperine pretreatment group, the expression level of iNOS was significantly lower than that in the LPC group. But the expression levels of Nrf2, Hmox-1 and MBP significantly increased in piperine pretreated group compared to LPC and control groups (P<0.001). Total antioxidant capacity of tissue in piperine pretreated group was more than that in the LPC group and controls (P<0.0001). Conclusion: Piperine improved spatial memory impairment induced by hippocampal demyelination through enhancing antioxidant defense and myelin repair.