大鼠海马-隔核投射及隔核毁损对海马Ghrelin调控学习记忆的影响

目的 观察大鼠海马神经元向隔核投射,探讨大鼠隔核对海马Ghrelin调控学习记忆能力的影响.方法 采用荧光金(FG)逆行追踪方法,观察大鼠海马神经元向隔区投射；采用立体定向电极毁损大鼠隔核,海马CA1区微量注射Ghrelin,利用跳台实验及Morris水迷宫进行定位航行实验和空间搜索实验,探讨大鼠隔核毁损后海马Ghrelin对大鼠学习记忆的影响.结果 隔核注射FG,7d后可见海马CA1,CA2,CA3区均有大量标记FG的神经元；海马CA1区注射Ghrelin可明显增加大鼠学习记忆能力,表现为跳台实验中大鼠从安全台跳下的潜伏期明显延长(3.2±0.9)s,(6.9±1.1)s,P＜0.05],5min内大鼠遭受电击次数明显减少(1.8±0.4)次,(0.8±0.1)次,P＜0.05],Morris水迷宫实验中大鼠找到平台的潜伏期明显缩短(19.5±3.2)s,(10.5 ±2.1)s,P＜0.05],但隔核毁损后,可明显减弱大鼠认知作用,表现为跳台实验中大鼠从安全台跳下的潜伏期明显缩短(3.9±0.8)s,(1.8±0.5)s,P＜0.05],5min内大鼠遭受电击次数明显增加(1.6±0.3)次,(4.0±0.7)次,P＜0.05],Morris水迷宫实验中大鼠找到平台的潜伏期明显延长(18.0±2.5)s,(32.8±5.5)s,P＜0.05].结论 海马CA1区Ghrelin可提高大鼠学习记忆能力,而该作用可能与隔核-海马间神经通路有关.

The projection of neurofibra from hippocampus to septal nucleus and the effect of hippocampus injection of ghrelin on learning and memory in septal nucleus lesion rats

Objective To investigate the tracking neurofibra pathway from the hippocamlpal neurons to septal nucleus,and to explore the effects and mechanisms of ghrelin on the learning and memory in septal nucleus lesion rats.Methods Retrogradely tracing method was used to observe Fluorogold (FG) reaching sites in hippocampus.The septal nucleus was destructed by direct current using stereotactic technique.Step-down test and morris water maze were used to test the effects of learning and memory ability by means of microinjecting ghrelin into hippocampal CA1 area in rats.Results After injection of FG into septal nucleus,retrogradely labeled neurons and neurofibra were found in the hippocampal neurons with FG.Ghrelin injection of hippocampal CAI area could promoter learning and memory ability in rats.It showed that the escaped latent period was significantly lengthened ( (3.2 ± 0.9) s vs (6.9 ± 1.1 ) s,P ＜ 0.05) and the wrong numbers in 5 min were obviously decreased in escape response test; and the latency of looking for the plat was significantly shorter in morris water maze test ( 1.8 ±0.4vs 0.8 ± 0.1,P ＜ 0.05 ).However the effects above-mentioned on learning and memory was significantly weak after septal nucleus lesioning.It showed that the escaped latent period was markedly shortened ( ( 19.5 ±3.2)s vs ( 10.5 ± 2.1 ) s,P ＜ 0.05 ) and the wrong numbers in 5 min were obviously increased ( ( 3.9 ± 0.8 ) s vs ( 1.8 ±0.5 ) s,P＜0.05 ) in escape response test.The latency of looking for the plat was significantly lengthened in morris water maze (P＜0.05).Conclusion Ghrelin could elevate the learning and memory ability in hippocampus,and the effects may be related to the septal-hippecampus pathway.