大鼠慢性吗啡处理后不同时间部分脑区腺苷酸环化酶Ⅷ基因表达的变化

Changes of adenylate cyclase Ⅷ expression in rat brain regions at different time points after chronic morphine exposure

目的 研究慢性吗啡处理的大鼠停药后不同时间部分脑区腺苷酸环化酶Ⅷ (ACⅧ )基因表达水平的变化。方法 将 2 4只雄性Sprague Dawley大鼠随机等分为吗啡依赖组 (吗啡组 ;在大鼠腹腔内注射盐酸吗啡 ,2次 /d ;起始剂量为 5mg/kg ,逐日递增 5mg ,至第 10天为 5 0mg/kg)及生理盐水对照组 (对照组 ;用相同方式注射同体积的生理盐水 ) ,于末次注射后 3h及 72h处死 (每组每时间点各 6只 ) ,取中脑腹侧被盖区 (VTA)、伏隔核 (NAc)、中脑导水管灰质 (PAG)、杏仁核 (AMG)、海马CA1区 (HIPCA1)等脑组织。利用组织原位杂交技术检测各脑区ACⅧmRNA的吸光度 (A)值 ,并作同期平行比较。结果 (1)末次注射 3h ,吗啡组NAc、PAG、AMG、HIPCA1的A值 (依次为 0 2 4 8±0 0 0 7、0 2 5 6± 0 0 11、0 2 6 8± 0 0 2 0、0 2 79± 0 0 16 )高于对照组 (依次为 0 2 34± 0 0 11、0 2 4 0±0 0 11、0 2 4 0± 0 0 11、0 2 5 1± 0 0 13;P <0 0 5～ 0 0 1) ,两组VTA的A值的差异无显著性 (P >0 0 5 )。 (2 )末次注射 72h ,吗啡组NAc、AMG的A值 (0 2 4 3± 0 0 0 7、0 2 5 2± 0 0 0 7)高于对照组(0 2 2 5± 0 0 12、0 2 2 5± 0 0 11;P <0 0 1) ,VTA、PAG的A值 (0 2 30± 0 0 10、0 2 2 8± 0

Objective To explore the changes of adenylate cyclase Ⅷ (ACⅧ) gene expression in defined brain areas of rats at the selected time points after chronic morphine exposure. Methods Twenty-four male Sprague-Dawley rats were randomly assigned into morphine or control group. Rats in morphine group were intraperitoneally injected with morphine twice a day for 10 days in ascending dosage schedule, accordingly rats in control group injected with saline of the same volume. After 3 or 72 hours of the final injection, rats were perfused and the brains were removed and cut coronally. The sections including ventral tegmental area (VTA), nucleus accumben (NAc), periaqueductal gray (PAG), amygdala (AMG), hippocampus CA1 (HIPCA1) were selected and mounted on slides. The mRNA levels of ACⅧ in selected regions were investigated with in situ hybridization and compared between groups according to identical time points. Results At the time point of 3 hours after the injection termination, the ACⅧ mRNA levels in the NAc, PAG, AMG, HIPCA1 (0.248±0.007, 0.256±0.011, 0.268±0.020, 0.279±0.016), but not in VTA, were significantly higher respectively in the morphine exposed rats compared with controls (0.234± 0.011, 0.240±0.011, 0.240±0.011, 0.251±0.013; P <0.05-0.01). The ACⅧ mRNA levels in morphine rats were still higher in the NAc, AMG (0.243±0.007, 0.252±0.007; P <0.01) at the time point of 72 hours, but lower in VTA, PAG (0.230±0.010, 0.228±0.008; P <0.01-0.05), than those of control, and no difference in HIPCA1 between the groups. Conclusion Chronic morphine administration may up-regulate the expression of ACⅧ, as the time elapsed, the increased ACⅧ gene expression may recover or down-regulate. It is indicated that the alteration of AC gene expression may be part of the molecular mechanism underlying opiate dependence and withdrawal.