The effects of sodium butyrate on ethanol-seeking behavior and H3K9 acetylation in NMDA receptor 2B subunit promotor region in the hippocampus of rats / 中华行为医学与脑科学杂志

ABSTRACT

Objective To investigate the effects of sodium butyrate on ethanol-seeking behavior and H3K9 acetylation levels in NMDA receptor 2B subunit(NR2B) promoter region in the hippocampus of Wistar rats.To explore the epigenetic mechanism underlying ethanol-seeking behavior.Methods According to random number table,48 male Wistar rats were divided into saline group,sodium butyrate group,ethanol group and sodium butyrate + ethanol group,with 12 rats in each group and administered by intraperitioneal injection respectively.Conditioned place preference (CPP)was used to evaluate the ethanol-seeking behavior.Using Western-blot,real-time PCR and chromatin immunoprecipitation assays,the expression of NR2B protein,NR2BmRNA and the relative level acetylated H3K9 in NR2B promoter region in the hippocampus were determined respectively.Results The CPP test and the CPP score in each group were different (P＜ 0.05).Compared with the CPP test(261.1 ± 102.2) and the CPP score(48.5±94.6) of saline group,the CPP test ((406.8±109.2),(502.7±72.89)) and the CPP score((198.2± 119.4),(277.5±76.2)) of ethanol group and sodium butyrate + ethanol group were significantly higher(P＜0.05),the CPP test(193.4±93.8) and the CPP score (9.7±94.0)of sodium butyrate group were not significantly different(P＞0.05).Compared with the ethanol group,CPP test of sodium butyrate + ethanol group was significantly higher(P＜0.05).The expression of NR2B protein,NR2BmRNA and acetylated level H3K9 in NR2B promoter region in the hippocampus in each group were different (P＜ 0.05).Compared with the expression of NR2B protein (1.00 ± 0.28),NR2BmRNA(1.00±0.14) and H3K9 acetylation in NR2B promoter region(1.00±0.25)in the hippocampus of saline group the expression of NR2B protein((1.40±0.34),(1.79±0.30)),NR2BmRNA((1.26±0.16),(1.50±0.08)) and aeetylated level H3K9 in NR2B promoter region ((1.68±0.16),(2.35±0.45)) of ethanol group and sodium butyrate ± ethanol group were significantly higher(P＜0.05).The expression of NR2B protein(0.85±0.24),NR2BmRNA(1.05±0.13) and acetylated level H3K9 in NR2B promoter region(0.96±0.41) of sodium butyrate group were not significantly different(P＞0.05).Compared with the ethanol group,the expression of NR2B protein,NR2BmRNA and acetylated level H3K9 in NR2B promoter region in the hippocampus of ethanol group,these of sodium butyrate + ethanol group were significantly higher (P＜0.05).The CPP score were positively correlated with the expression of NR2B protein (r=0.474,P＜0.05).The expression of NR2B protein were positively correlated with the expression of NR2BmRNA (r=0.468,P＜0.05).The expression of NR2BmRNA were positively correlated with the expression of H3K9 acetylation in NR2B promoter region(r=0.596,P＜0.05),and the CPP score were positively correlated with the expression of H3K9 acetylation in NR2B promoter region (r=0.542,P＜0.05).Conclusion The increasing acetylation level of H3K9 in NR2B promoter region in the hippocampus may be one of the epigenetic mechanisms of promoting ethanolseeking behavior,and H3K9 deacetylation in NR2B promoter region in the hippocampus is likely to be a new target for controlling ethanol dependence.