小鼠海马齿状回过表达18ku转位蛋白对焦虑和抑郁样行为的调节作用

Overexpression of 18ku translocator protein in mouse hippocampal dentate gyrus mediates anxiety and depressive behavior

目的研究小鼠海马齿状回18 ku转位蛋白(TSPO)过表达对焦虑、抑郁样行为的影响,为TSPO成为药物潜在新靶标提供实验依据。方法成年雄性ICR小鼠海马齿状回每侧微注射携带TSPO基因的慢病毒(LV)(2×108TU·m L-1),以致TSPO过表达(LV-TSPO)。第12,14和16天进行小鼠高架十字迷宫、爬梯实验、明暗箱实验检测焦虑样行为,第18和21天进行小鼠悬尾和强迫游泳行为绝望模型检测抑郁样行为;行为学实验结束,采用Western蛋白印迹法和ELISA方法分别检测海马注射孔周围3 mm组织内TSPO蛋白水平和四氢孕酮含量。结果小鼠海马齿状回微注射慢病毒后12 d,小鼠跨格数和站立次数无明显改变;与LV组相比,LV-TSPO组显著增加小鼠进入中心区时间(14±4 vs 25±12,P<0.05);显著增加小鼠进入开臂次数和开臂时间的百分比〔(13±8)%vs(26±18)%,P<0.05;(6±6)%vs(27±6)%,P<0.05)〕;显著减少小鼠站立次数(21±7 vs 12±5,P<0.05);显著增加小鼠进入明箱的次数和时间〔18±8 vs(26±7)s,P<0.05;72±36 vs(191±90)s,P<0.05〕,提示海马齿状回TSPO过表达小鼠表现出显著的抗焦虑样行为作用;与LV组相比,LV-TSPO组明显减少小鼠在悬尾实验和强迫游泳实验中的不动时间〔(94±33 vs(36±20)s,P<0.01;137±36 vs(90±37)s,P<0.05〕,提示海马齿状回TSPO过表达小鼠表现出显著的抗抑郁样作用。与LV组相比,小鼠海马齿状回TSPO过表达可导致海马注射孔周围3 mm组织四氢孕酮含量显著增加(P<0.05)。结论小鼠海马齿状回过表达TSPO具有显著的抗焦虑、抗抑郁样的行为学效应,且TSPO介导的四氢孕酮水平升高可能是其重要机制。

OBJECTIVE To investigate the effect of overexpession of 18 ku translocator protein（TSPO） on the hippocampal dentate gyrus. METHODS Lentiviral（LV） vectors containing TSPO or the lentiviral sequence were infused into the hippocampus bilateral dentate gyri（2×108TU·m L-1,1 μL per side）of mice. Behavioral tests were carried out. The anxiolytic-like behavior of mice was examined by such means as the elevated plus maze test, the staircase test, light dark box test for 12, 14 and 16 d,two behavioral despair models, tail suspension test and the forced swimming test for 16 and 18 d,respectively. Western blotting and ELISA were used to evaluate the TSPO expression and the concentration of allopregnanolone in hippocampal tissue（3 mm in diameter around the injection site on both sides） at the end of tests. RESULTS The results of behavioral experiments showed that TSPO overexpression group deneloped anxiolytic and antidepression-like behavior. LV-TSPO significantly increased the retention time in the central area〔14 ± 4 vs（25 ± 12）s,P〈0.05〕. LV-TSPO significantly increased the percentage of entry into open arms entries percentage and the percentage of time spent in open arms time without changing total entries and total time in the elevated plus-maze test〔（13±8）% vs（26±18）%,P〈0.05;（6±6）% vs（27±6）%, P〈0.05）〕. LV-TSPO significantly decreased the number of rearings without changing the number of steps in staircase test（21±7 vs 12±5,P〈0.05）. LV-TSPO increased entries into the light area and retention time in light-dark transition test〔（18±8）% vs（26±7）%, P〈0.05;72±36 vs（191±90）s, P〈0.05）〕but significantly decreased immobility time in the tail suspension test and forced swimming test〔94±33 vs（36±20）s, P〈0.01; 137±36 vs（90±37）s, P〈0.05）〕, without excitatory or inhibitory actions on the central nervous system. At the same time, the level of TSPO expression in hippocampal tissues（3 mm in diameter around the injection site on both sides） was significantly increased, so did the concentration of al opregnanolone（P〈0.05）. CONCLUSION Overexpression of TSPO in the hippocamus dentate gyrus of mice can induce anxiolytic and antidepressant-like behavior, and the downstream allopregnanolone biosynthesis at least partially mediates the behavioral effects.