The behavior effect of IGF-1 on dementia rats and the likelihood mechanism

Objective To study the effects of insulin-like growth factor-1(IGF-1) on the learning and memory abi1ities of dementia rats and to revea1 the 1ikelihood mechanism.Methods We established the dementia rat models by transecting bilateral fornix-fimbria and divided them into five groups: normal control group,sham group,dementia group,low dose IGF-1 group and large dose IGF-1group.Dementia model rats received IGF-1(low dose IGF-1 group,large dose IGF-1group)or saline(sham group,dementia group)by infusion into the cerebroventricular space for 21 days after the operation.The normal control group accept no treatment.The learning and memory abilities were measured by Morris water maze.We used hybridization in situ technique and image analysis system to observe the changes of ChAT in hippocampus and frontal lobe of dementia model rats and immunohistochemistry to observe the changes of synaptophysin.Results Compared to normal control group,learning and memory abilities of dementia group were declined and the density of ChAT and synaptophysin was decreased significantly(P0.001).In comparison with dementia control group,learning and memory abilities of low dose IGF-1 group and large dose IGF-1group were improved and the density of ChAT and synaptophysin was increased significantly and the low dose IGF-1 group is better than the large dose IGF-1 group(P0.01).Conclusion IGF-1 can improve the learning and memory abilities of the dementia rats.The increasing of ChAT and synaptophysin density is the possible mechanism of the behavior effect of IGF-1 on dementia rats.