ABSTRACT
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.