*3.1. Chronic Administration of Curcumin Inhibits Ethanol-Induced Oxidative Stress in Mice Brains and In-Vitro HT22 Cells*

Oxidative stress has been a significant player in ethanol [35] and other neurotoxins-induced neurodegenerative disorders [36,37]. To find the potential effects of curcumin against ethanol-induced oxidative stress, we performed ROS and LPO assays. According to our findings, curcumin inhibits the elevated level of LPO and ROS (Figure 1A,B). Similarly, the other main antioxidant genes, Nrf2/HO-1, were also analyzed in the experimental groups. According to our Western blot and confocal findings, the chronic co-administration of curcumin with ethanol inhibited the suppression of Nrf2/HO-1 in the mice brains, thereby preserving the endogenous antioxidant mechanism of the brains (Figure 2C,D). Furthermore, we observed a reduced expression of Nrf2 and its target genes HO-1, in the ethanol (100 μM) exposed HT22 cells, which was markedly reversed by curcumin (2 μM), thereby upregulating the expression of Nrf2 and HO-1 in the cells. Interestingly, curcumin could not upregulate the expression of Nrf2/HO-1 in the ethanol-treated cell lines, where the Nrf2 genes were knocked down by Nrf2 siRNA (Figure 1E), indicating that curcumin abrogated the elevated ROS, by upregulating the Nrf2 genes, and the downstream targets of Nrf2.
