| OBJECTIVE:To investigate the brain-protective effect of Melatonin in cerebral vasospasm after subarachnoid hemorrhage.MATERIALS AND METHODS:Model of subarachnoid hemorrhage that is established by injecting autologous arterial blood to cisterna magna of Sprague-Dawley(SD) rats in this study.120 healthy adult Sprague-Dawley(SD) rats were divided randomly into 4 groups, and each group was divided into 5 subgroups according to different time points designed in advance with 6 adult Sprague-Dawley(SD) rats in each subgroup.Group A:sham-operated control group includes the subgroup A1,A6,A12,A24 and A72,which were raised respectively 1hour,6hours,12hours,24 hours and 72hours after sham operation; Group B:SAH+NS control group,includes subgroup B1,B6,B12,B24 and B72,which were raised respectively 1hour,6hours,12hours,24hours and 72hours after establishment of SAH+NS model;Group C:SAH group,included:subgroup C1,C6,C12,C24 and C72,which were keeped respectively 1hour,6hours,12hours,24hours and 72hours after establishment of SAH+NS model;Group D:SAH+MT group,subgroup D1,D6,D12,D24 and D72 were raised respectively 1hour,6hours, 12hours,24hours and 72hours after establishment of SAH+MT model. Rats of Group A,Group B,Group C and group D were decapitated and the brains were harvested according to different time points designed in advance.Coronal sections of brain tissue were taken post to the optic chiasm for respectively 1 and 4 mm.The histopathological changes and ultrastructure of cerebral hippocampus CA1 subarea were exmined by HE staining and the expressions of Bcl-2 and Bax were studied by immunohistochemistry.All the experimental datas were analyzed by SPSS 13.0 software.RESULTS:HE-stained slides were observed under Optical microscope.: vessel wall of basilar arteries in Group A are smoothing,not thickened, and structure of vessel walls was integral.Blood vessel diameters of Group B and Group C are diminished,and endothelial cells of basilar arteries in Group B and Group C are manifested in degeneration and engorgement.Blood vessel wall of Group D are little shrinked,and endothelial cells of vessels in Group D are less engorgemented than Group B and Group C.Then observation of hippocampus CA1 subarea and counting of survival neuron dense under microscope showed:Apoptosis of neurones in Group A are observed rarely;Apoptosis of neurones of great number are observed in Group B and C.Group D showed obviously reduce of apoptosis of neurones compared to Group B and C of the same time points.Immunohistochemical staining of Bcl-2 and Bax,positive cells manifested:homogeneous diffuse brown color in cellplasm.(1)Positive stained cells of Bcl-2 are very rare in hippocampus in subgroups of Group A with shallow stain;Positive stained cells are abundant in subgroups of Group B,C and D.Positive stained cells in group D are great in number and deeply stained compared to the subgroups in Group B and C.(2)The same result can be found with respect to the expression of Bax.Positive stained cells of Bax are very rare in hippocampus in subgroups of Group A with shallow stain; Positive stained cells are abundant in subgroups of Group B,C and D. Positive stained cells in group D are great in number and deeply stained compared to the subgroups in Group B and C.After statistical analysis and through comparison among the groups and subgroups,we found the survival neuron dense and expression of Bcl-2 and bax Significantly different.1,Simple injury of incision and isotonic Na chloride will not manifestly influence vascular endothelial cell and the express of Bcl-2and Bax in brain tissue.2,The expression of Bcl-2 and Bax in brain tissue is enhanced by subarachnoid hemorrhage.3,Melatonin possibly play a role in brain-protective by enhancing the expression of Bcl-2 in brain tissue,Inhibition the express of Bax in brain tissue and inhibiting apoptosis of neurones.4,Melatonin may have a Vasodilative effect in CVS blood vessels after SAH,but the mechanism of this effect is unknown.Further investigation is still needed. |
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