母鼠孕期摄入乙醇对子鼠背侧中缝核内5-羟色胺合成的影响

Effects of prenatal alcohol exposure on serotonin in the rat dorsal raphe nuclei

[目的]探讨母鼠孕期摄入乙醇对子鼠背侧中缝核内5-羟色胺(5-HT)合成的影响.[方法]选择SD母鼠24只,于怀孕第6日随机分为乙醇组、正常对照组和代理母组.乙醇组母鼠每日摄取热量为35 cal的乙醇,正常对照组母鼠为35 cal糊精,代理母组母鼠为普通饲料.乙醇组、正常对照组母鼠分娩6 h后与其子鼠分开,麻醉后心脏采血,检测血液中乙醇和甲状腺素水平.乙醇组及正常对照组新生子鼠由代理母组代理母鼠养育,并分别于出生后0,7,14,21,28 d时麻醉处死子鼠,采用免疫组织化学ABC染色法观察子鼠背侧中缝核内含有5-HT的神经元的分布及形态.[结果]乙醇组母鼠血中乙醇浓度明显高于正常对照组,而乙醇组母鼠血中甲状腺素水平明显低于正常对照组.正常对照组子鼠生后7 d开始出现成熟的含有5-HT的神经元,即可观察到长而突起明显的、双极或多极的含有5-HT的神经元,出生后14 d开始出现含有5-HT神经元突起所形成的分支及其相互间的连接.乙醇组子鼠始终未出现具有上述表现的成熟的含有5-HT的神经元.在所有时间段中,乙醇组子鼠含有5-HT的神经元数均较正常对照组明显减少,并于生后第7日开始显著减少.[结论]母鼠孕期摄取乙醇不仅可引起血中甲状腺素水平降低,而且可抑制后代背侧中缝核内5-HT的合成及神经元的发育.

OBJECTIVE To investigate the changes of serotonin 5-hydroxytryptamine （5-HT） in the rat dorsal raphe nuclei with prenatal alcohol exposure. METHODS Twenty-four time-pregnant SD rats were divided into three groups on the 6th day of gestation. Alcohol group received 35 calories of liquid alcohol diet every day; control group was fed a liquid diet in which dextrin replaced alcohol isocalorieally; surrogate group intook food normally. Blood samples were obtained by cardiac puncture, under anesthesia, from alcohol and control groups within 6 h after its last pup was born. The plasma concentrations of alcohol and thyroxine were determined. Pups of alcohol and control groups were fostered by surrogate mothers, and executed at anesthesia at postnatal 0, 7, 14, 21 and 28 days for measuring the distribution and form of nerve cells containing serotonin via immunohistochemistry in the dorsal raphe nuclei. RESULTS The blood alcohol concentration was higher in alcohol group dams than in control group, with significant difference. Thyroxine concentration was significantly decrease in alcohol group dams than in control group. In control group was observed mature serotonin containing nettrons on and after the postnatal 7 days, many of these cells were.bipolar or multipolar in shape and their processes had increased in length and thickness, since postnatal 14 day, their fibers and terminals formed a rich network. In contrast, the maturation of serotonin-containing neurons was not found in alcohol group at all ages. The obvious decrease of serotonin-containing neurons was observed in alcohol group compared to control group at all ages, and significant reduction of serotonin-containing neurons was found after 14 days of birth. CONCLUSION When dams exposured alcohol within gestation, not only the blood thyroxine concentrationwas significantly decreased in dams, but also serotonin synthesis of dorsal raphe nuclei and growth of serotonin-containing neurons were impaired in offsprings.