Morphological Plasticity Study In The Hippocampal Formation During The Spatial Discriminative Learning And Memory In Rats.

PurposeThe aim of this study was to explore the relationship between the morphological plasticity of hippocampus structure and the expression changes of nervous factor correlated with the plasticity , when rats obtained the function of spatial discriminative learning and memory.MethodsRats were trained to become the animal models of spatial discriminative learning and memory with water maze. Then, Timm method, immunohistochemical method and western-bloting metheod were used to test the relationship between the nervous sprouting phenomenon about morphological plasticity and expression changes of nervous factor ephrin-A3 correlated with the plasticity in hippocampus structures among model rats, swimming rats and controled rats. Results1. The result of building animal models of spatial discriminative learning and memory : on the 7^th training day, the average latent, the average running time and the correct ratio of all three quotas reached the standard on references ;2. The result of nervous plasticity in rats hippocampus structures among groups: (1) rats in the model group showed sprouting moss fibers at the polymorphic layer in their hippocampal CA3 subfield with Timm method. Furthermore, the extent of nervous fibers sprouting reached to a peak on the 14^th training day; In the model group, 8rats out of 9(88.8%)showed sprouting moss fibers ;(2) In the swimming group, 7rats did not show nervous fibers sprouting. Two rats out of 9(22.2%)showed sprouting moss fiber at the polymorphic layer of CA3subfield..(3)In the control group, All of 9rats did not show sprouting moss fibers at the polymorphic layer of CA3subfield3. The result of distribution and quantity about ephrin-A3 in hippocampus formation: On the respect of distribution about expression of ephrin-A3, immunoreactivity positive products of ephrin-A3 existed in every subfield and layers of rat hippocampusformation among model group, swimming group and control group, but those in the stratum radiatum of CA3 were especially obvious in model group. A significant increase ( P<0.0l ) in the content of ephrin-A3 can be found in the rat hippocampus structure, comparing with that of the swimming group and control group. Moreover, the quantity of ephrin-A3 in rats hippocampus structures of swimming group was higher than that of rats of control group (P<0.0\) .In model group, the quantity of ephrin-A3 in rats hippocampus at thel4th day and 21th day were higher than that of rats at the 7th day (P<0.01) . Conclusions1. The animal models of spatial discriminative learning and memory can be established by training rats with water maze.2. when rats obtained the function of spatial discriminative learning and memory, the plasticity changes of nervous fibers would take place in their hippocampus structures3. There is a correlated relationship between the ephrin-A3-immunoreactivity positive products and sprouting nervous fibers in hippocampus structure..