The Nucleus Accumbens Shell and Central Nucleus of the Amygdala of Alcohol-Preferring Rats Following Binge-Drinking

The objective of this study was to determine changes in gene expression within the extended amygdala following binge-like drinking by alcohol-preferring (P) rats. Adult male P rats were given 1-hr access to 15 and 30% ethanol (EtOH) three times daily for 8 weeks. Rats (n = 10/time point for EtOH and n = 6/time point for water) were killed by decapitation 1, 6 and 24 hr after the last drinking episode. Brains were extracted and rapidly frozen in isopentane in dry ice. RNA was prepared from individual micropunch samples of the nucleus accumbens shell (ACB-sh) and central nucleus of the amygada (CeA); microarray analyses were conducted with Affymetrix Rat 230.2 chips. EtOH intakes were 1.5-2 g/kg/session. Because too few genes changed at the individual time points, an overall effect, comparing the water and EtOH groups, was determined. In the ACB-sh and CeA, there were 276 and 402 probe sets for named genes, respectively, that were different between the two groups. There were 1.5- to 3.5- fold more genes up-regulated than down-regulated in both regions, with most differences between 1.1- to 1.2-fold. Although there were several significant Biological Processes categories in common between the 2 regions (e.g., synaptic transmission, neurite development), there were few genes in common between the two regions that differed between the EtOH and water groups. Overall, the results suggest that chronic binge-like alcohol drinking by P rats produces changes in the expression of genes that could alter neuronal function by different mechanisms in the ACB-sh and CeA.本研究旨在明确酒精偏好型（P）大鼠经类暴饮式饮酒后，其扩展杏仁核内的基因表达变化情况。实验选用成年雄性P大鼠，每日给予三次、每次1小时的15%与30%乙醇（EtOH）溶液接触机会，持续8周。在末次饮酒后的1、6及24小时，分别处死大鼠（乙醇组每个时间点n=10，饮水组每个时间点n=6），采用断头法处死。取出脑组织后，将其置于干冰冷却的异戊烷中快速冷冻。从伏隔核壳部（nucleus accumbens shell, ACB-sh）与杏仁核中央核（central nucleus of the amygdala, CeA）的微穿刺取样样本中提取RNA，采用Affymetrix大鼠230.2基因芯片开展微阵列分析。单次饮酒的乙醇摄入量为1.5~2 g/kg。由于单个时间点的差异表达基因数量过少，本研究通过比较饮水组与乙醇组的整体差异来确定整体效应。在伏隔核壳部与杏仁核中央核中，分别有276个和402个对应已知基因的探针组在两组间存在显著差异。两个脑区中上调基因的数量均为下调基因的1.5~3.5倍，且多数差异倍数介于1.1~1.2倍之间。尽管两个脑区共有多个显著富集的生物学过程类别（如突触传递、神经突发育），但两组间存在差异表达的共有基因数量极少。综上，本研究结果表明，酒精偏好型大鼠长期类暴饮式饮酒可通过不同的分子机制，在伏隔核壳部与杏仁核中央核中改变基因表达，进而影响神经元功能。