氟马西尼逆转惊厥易感大鼠氟西泮耐受性的分子机制

Molecular mechanism of the tolerance to flurazepam and reversal of tolerance with flumazenil in genetically epilepsy-prone rats

目的 :探讨苯二氮类的抗耐受性和用氟马西尼逆转耐受性的受体分子机制。方法 :腹腔注射氟西泮2周 ,产生有氟西泮耐受性而无依赖性的听源性惊厥大鼠模型。一组大鼠于用药第 8天 ,腹腔注射一次氟马西尼 (4mg·kg-1) ,观察其对耐受性的影响。用竞争性定量RT PCR测定大鼠脑皮质运动区和海马区的GABAA 受体α1、α3 、α5、γ2L和γ2S亚单位mRNA的含量。结果 :氟西泮耐受组大鼠皮质运动区的α1亚单位下降 2 4%,α3 下降 17%,α5上升 33%,γ2L下降 35 %,γ2S下降 45 %;海马区的α1下降 33%,γ2L下降 35 %,γ2S下降 2 7%,与对照组比较差异均有显著性。合用氟马西尼组大鼠皮质运动区γ2L亚单位下降 33%,γ2S下降 40 %,海马区γ2L下降 31%,γ2S下降 2 9%,与对照组比较差异均有显著性 ;皮质运动区α1、α3 、α5和海马区α1亚单位与氟西泮耐受组不同 ,差异均无显著性。结论 :听源性惊厥大鼠的氟西泮耐受机制与中枢GABAA 受体α1、α3 、α5、γ2L和γ2S亚单位mRNA含量的适应性改变有关。氟马西尼可逆转氟西泮耐受性 ,并影响上述亚单位的含量。

Objective: To investigate the molecular mechanism underlying the tolerance to flurazepam and reversal of the tolerance by flumazenil. Methods: Audiogenic seizure rats were administrated with flurazepam for two weeks, which resulted in tolerance to flurazepam, in the absence of behavioral signs of withdrawal. One rat group was exposed to a single dose of flumazenil (4 mg·kg -1 )on day 8 to observe the effect of flumazenil on the tolerance to flurazepam. GABA A receptor subunits α 1, α 3, α 5, γ 2L and γ 2S were assayed using quantitative competitive RT PCR in rat PrPaM and hippocampus. Results: In flurazepam group the contents of mRNA encoding for α 1, α 3, γ 2L and γ 2S were all significantly decreased (24%, 17%, 35% and 45% respectively). In frontparietal motor(FrPaM), whereas that of α 5 was significantly increased (33%) compared with the control. In hippocampus, α 1, γ 2L , and γ 2S mRNA contents were significantly decreased (33%, 35%and 27% respectively). In flumazenil reversal group, γ 2L and γ 2S mRNA's were significantly decreased (33%, 40% respectively) in rat FrPaM, and γ 2L and γ 2S mRNA's significantly decreased (31%, 29% respectively) in hippocampus. No significant change was found with α 1, α 3 and α 5 in FrPaM, and α 1 in hippocampus, which was different in flurazepam group. Conclusion: The accommodated change in GABA A receptor subunits α 1, α 3, α 5, γ 2L and γ 2S in FrPaM and hippocampus might be associated with the molecular mechanism for flurazepam tolerance in audiogenic seizure rats. Flumazenil could reverse the tolerance to flurazepam and affected 基金项目:国家自然科学基金(39670768)资助 Supported by the National Natural Sciences Foundation of China (39670768) the modification of subunit contents in GABA A receptor mentioned above.