尼古丁暴露和饮酒行为对大鼠腹侧被盖区烟碱型乙酰胆碱受体表达的影响

目的 探讨尼古丁暴露和饮酒行为对大鼠腹侧被盖区(VTA)烟碱型乙酰胆碱受体(nAChR)部分亚单位mRNA表达的影响.方法 39只出生35 d的雄性Wistar大鼠随机分为实验组(N组,n=20),和对照组(C组,n=19),N组大鼠进行为期10d的尼古丁(1.0mg·kg-1·d-1)皮下注射,C组大鼠以生理盐水对照处理10d.其后,在N组和C组大鼠中各随机抽取6只(分别为NE组,n=6,和CE组,n=6)大鼠断头取脑分离VTA区提取mRNA,实时定量检测nACh受体α4、α5、α7和β2亚单位表达.N组和C组其余大鼠(分别为NA组n=14,CA组n=13)在出生后60d以Samson糖水递减程序诱导建立双瓶自由选择饮酒行为模型,共计69d,之后以相同程序定量检测VTA区标本相同指标.结果 ①因素分析显示:两因素(尼古丁暴露、饮酒行为)对VTA区nAChRα4、α5亚单位表达水平均有调节作用(F值分别为6.13,5.407,5.186,7.132,P＜0.05)；饮酒行为因素对β2亚单位表达水平有调节作用(F=5.896,P＜0.05)；两因素对α7亚单位表达有极强的交互作用(F=13.894,P＜0.001),对α5、β2亚单位表达有交互作用(F值分别为6.149,4.222,P＜0.05).②NA组α4、α5、α7和β2亚单位mRNA表达不同程度的显著高于CA组(F值分别为7.941,13.517,17.438,9.272,分别P＜0.05、P＜0.05、P＜0.01、P＜0.01),NA组的α4、α5、α7、β2亚单位表达水平显著高于NE组(F值分别为5.293,8.500,6.149,4.837,P＜0.05)；CA组α7亚单位表达水平显著低于CE组(F=12.750,P＜0.01).结论 尼古丁和乙醇共同作用于VTA区包含有α4、α5、α7、β2亚单位的nAChR亚型.

Effects of nicotine exposure and ethanol-preferring behavior on mRNA expression of some nAChR subunits in the rat VTA

Objective To investigate the effects of nicotine exposure and ethanol-preferring behavior on mRNA expression of some nAChR subunits in the rat ventral tegmental area(VTA) and to explore possible mechanisms of dependence on tobacco and alcohol.Methods 39 male Wistar rats,35-day-old,were randomly divided into an experimental group (group N,n=20) and a control group (group C,n=19).Rats in group N were treated with nicotine ( 1.0 mg · kg -1 · d -1 ) by subcutaneous injection while in group C with saline both for 10 days,after which 6 rats (respectively group NE,n =6,group CE,n =6 )were drawn randomly from each group and killed by cutting off the head.mRNA was extracted from the VTA tissue,and the expression of nAChR subunits,including α4,α5,α7 and β2,were examined by Real Time-PCR.Other rats both in groups N and C ( respectively group NA,n=14,group CA,n=13) were induced for 69 days to establish two-bottle free choice alcohol-preferring behavior model by Samson sucrose fading program from 60-day-old on.The same indexes mentioned above were detected by the same methods in the VTA tissue.Results ① The factor analysis showed that both the two factors,nicotine and alcohol-preferring behavior,showed regulating effects on the expression of nAChR subunits α4 and α5 ( respectively F was 6.13,5.407,5.186,7.132,P ＜ 0.05 ),and the factor,alcohol-preferring behavior,on subunit β2 (F =5.896,P＜0.05) ; the two factors exhibited strong interaction on the expression of subunit α7 (F=13.894,P＜0.001 ),and some interaction on subunits α5 and β2 (respectively F was 6.149,4.222,P＜0.05 ).② The mRNA expression of nAChR subunits α4,α5,α7,and β2 were significantly up-regulated by different degrees in group NA compared to group CA ( respectively Fwas 7.941,13.517,17.438,9.272,respectively P ＜ 0.05,P ＜ 0.05,P ＜ 0.01,P ＜ 0.01 ),the expression level of subunits α4,α5,α7 and β2 were significantly higher in different degrees in group NA than in group NE( respectively F was 5.293,8.500,6.149,4.837,P ＜0.05) ; while subunit α7 was significantly down-regulated in group CA compared to group CE (F =12.750,P ＜0.01 ).Conclusion Nicotine and ethanol co-affect on the nAChR subtype comprised of subunits α4,α5,α7 and β2.