Protective effect and mechanism of Lycium barbarum L. polyphenol on cognitive impairment induced by ethanol in mice

Abstract

BackgroundChronic excessive ethanol consumption damages the central nervous system and causes neurobehavioral changes, such as cognitive impairment, which is related to oxidative stress and inhibition of neurogenesis in the hippocampus. It is known that promoting neurogenesis improves learning memory, anxiety and depression. Lycium barbarum L. polyphenol (LBP) is the main active ingredient of Lycium barbarum L., which has excellent neuroprotective effects. However, the effects and mechanisms of LBP on ethanol-induced cognitive impairment are unclear. PurposeTo assess the effects and mechanisms of LBP on ethanol-induced cognitive impairment in mice. MethodsEight-weeks-old adult C57BL/6J mice were allowed to drink ethanol (10%) to establish a model of ethanol-induced cognitive impairment. From the 29th day of LBP (25, 50, 100, 200, 400 mg/kg, intragastric administration), the locomotor activity, novel object recognition (NOR), Y maze and Morris water maze (MWM) were sequentially performed to investigate the effect of LBP on ethanol-induced cognitive impairment in mice. Next, enzyme-linked immunosorbent assay, immunofluorescence, and western blotting were used to study the underlying mechanism of LBP on ethanol-induced cognitive impairment. ResultsLBP significantly decreased the escape latency and increased the number of crossings of the original platform in MWM, increased the spontaneous alteration behavior in the Y maze, and increased the preference index in the NOR in ethanol-induced mice. Notably, LBP significantly promoted the proliferation of neural stem cells, neural progenitor cells and neuroblasts, and increased the proportion of activated NSCs in mice with ethanol-induced cognitive impairment. Similarly, LBP significantly increased the number of newborn immature neurons and mature neurons. Moreover, LBP increased the levels of nuclear factor erythroid2-related factor 2 (Nrf2) and the downstream heme oxygenase-1(HO-1) protein expression, which led to a decrease of oxidative stress levels. ConclusionLBP significantly improves cognitive impairment in ethanol-induced mice, which is attributed to the promotion of hippocampal neurogenesis and reduction of oxidative stress.