海马齿状回的5-HT_(1A)受体在大鼠主动回避学习中的作用

Effect of 5-HT_(1A) receptors in the hippocampal DG on active avoidance learning in rats

目的:探讨海马齿状回(DG)的5-HT1A受体在大鼠主动回避学习中的作用。方法:SD雄性大鼠36只,随机分为训练组、阻断剂组和激动剂组及相应的对照组(n=6)。在清醒自由状态下,用脑部微量透析法和高效液相色谱法观察海马DG的5-羟色胺(5-HT)含量在主动回避学习过程中的变化;向海马DG微量注射5-HT1A受体阻断剂WAY-100635或激动剂8-OH-DPAT,观察其对大鼠主动回避学习的影响。结果:1大鼠主动回避学习过程中,DG区细胞外液中的5-HT含量在条件反射建立过程中无显著变化,但实验性消退开始时出现明显升高,达到训练前的(164.90±26.07)%(P<0.05);2每轮训练前,向DG微量注射WAY-100635对大鼠主动回避学习未产生显著影响;3每轮训练前向DG微量注射5-HT1A受体激动剂8-OH-DPAT,能促进条件反射的建立,并抑制条件反射的消退(均P<0.05)。结论:激活海马DG区的5-HT1A受体可易化主动回避学习并巩固相关记忆。

Objective： To investigate the effects of serotonin（ 5-HT1A） receptors in the hippocampal dentate gyrus（ DG） on active avoidance learning in rats. Methods： Totally 36 SD rats were randomly divided into control group,antagonist group and agonist group（ n = 12）. Active avoidance learning ability of rats was assessed by the shuttle box. The extracellular concentrations of 5-HT in the DG during active avoidance conditioned reflex were measured by microdialysis and high performance liquid chromatography（ HPLC） techniques. Then the antagonist（ WAY-100635） or agonist（ 8-OH-DPAT） of the 5-HT1 Areceptors were microinjected into the DG region,and the active avoidance learning was measured. Results： ①During the active avoidance learning,the concentration of 5-HT in the hippocampal DG was significantly increased in the extinction but not establishment in the conditioned reflex,which reached 164. 90% ± 26. 07%（ P〈0. 05） of basal level. ② The microinjection of WAY-100635（ an antagonist of 5-HT1Areceptor）into the DG did not significantly affect the active avoidance learning. ③ The microinjection of 8-OH-DPAT（ an agonist of 5-HT1Areceptor） into the DG significantly facilitated the establishment process and inhibited the extinction process during active avoidance conditioned reflex. Conclusion： The data suggest that activation of 5-HT1 Areceptors in hipocampal DG may facilitate active avoidance learning and memory in rats.