| Objective:To observe the changes of dopamine D1, D2 receptors' expression following multiple cerebral concussion(MCC) of the brain in rats .Our target is to study the path-machanism of sports-related cerebral concussion(SRCC). Methods: Animal modle of MCC was induced by a metallic pendulum striker device. Animals subjected MCC were randomized into six injured groups (the group of 1d, 2d, 4d, 8d, 16d and 24d post-concussive injury). Intacted rats was served one control group. The brain was cut at section of MSN and HI. Dopamine Dl, D2 receptors were marked respectively used anti-D1 polyconal antibody and anti-D2 monoclonal antibody by the immunohistochemistry (streptavidin-peroxi-dase , S-P) method (D1R:n=2; D2R:n=8) . The distribution of D1R and D2R positive neuron was observed by light microscope; Then the changes of D1R positive reaction were described. The positive reaction of D2R neuron was quantitatively analyzed by image analysis system. The data were analyzed by one-way ANOVA. Results:1．The positive reaction of D1R located at the neurons of FPC, MSN, VDB, HI CA1-4, RT and CPU. The expression of D1R decreased significantly at the 1st day after injury in FPC, MSN, VDB, HI CA3 and RT, then recovered increasingly . Till the 24th day , the expression of D1R in the neurons of RT and HI CA3 reached normal, but still subnormal in the neurons of MSN, VDB and FPC. 2．The positive reaction of D2R located at the neurons of VDB, MSN, FPC, CPU, EN, HI CA1-4, AM and RT.The expression of D2R in MSN decreased at first after injury, and reached the lowest at the 4d group, then recovered increasingly , but still subnormal till the 24th day. The expressive changes of D2R in the neurons of VDB and EN was similar to MSN. The expression of D2R in the neurons of FPC after injury went down at the 1d group, and reached the lowest at the 8d group, then recovered increasingly , but still subnormal till the 24th day. The expression of D2R in CPU decreased at first, then recovered normal at 24d group, the expressive valley at the 16d group. There was significant different in neurons of MSN at 1d, 2d and 4d groups (p<0．05) ,in VDB at 1d, 2d, 4d, 16d and 24d groups(p<0．05) , in PFC at 1d, 2d, 4d, 8d, 16d and 24d groups (p<0．05) , in CPU at 8d and 16d groups (p<0．05) , and in neurons of EN at 4d groups(p<0．05) compared with the control. The expression of D2R in the neurons of HI (CA1-CA4) deregulated after injury. Two expressive valleys were formed in each area of HI. The two valleys located at 2d and 24d group in CA1 and CA4, at 2d and 8d in CA2, at 2d and 16d in CA3．There was significant different at 2d and 24d groups in neurons of CA1 (p<0．05) , at 2d group in CA3 (p<0．05) . There was no significant different in neurons of AM and RT compared with the control group. Conclusion:1．The model of multiple cerebral concussion(MCC) in rats can be established successfully by iron pendulum hitting device;2．The dopamine D1 receptor were expressed on cellular membrane of neurons in FPC, MSN, VDB, HI CA1-4, RT and CPU. The expression of D1R in those regions decreased in different degree found under light microscope after injury. 3．The positive expression of D2R existed on the cellular membrane of neurons in VDB, MSN, FPC, CPU, EN, HI,AM and RT. The expression of D2R in those regions deregulated in different degree after injury analyzed by image analysis system, arid there was significant difference in VDB, MSN, FPC, CPU, AM and HI (CA1, CA3) (p<0．05) . 4．The changes of D1R, D2R in related brain regions involved in locomotive and cognitive behavioral deficits in MCC rats at some extent.
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