The Expression Of P38MAPK, P53 And The Effect Of Melatonin In Early Brain Injury Following SAH In Rats

Objective: The study is to observe the neurobehavioral changes and the morphological changes of basal artery and to test the expression of p38Mitogen-activated protein kinase(p38MAPK) and P53 in the temporal lobe cortex and basal artery walls of the rats in the early stage after subarachnoid hemorrhage(SAH). The study further aim is to discuss the association between the expression of p38 MAPK, P53 and early brain injury(EBI)following SAH and effect of melatonin(MT) on neurobehavioral and morphological of basal artery in SAH rats. Meanwhile we explore how would MT impact on the expression of p38 MAPK and P53, in order to provide clues and experimental basis for further research about the application of melatonin in SAH.Methods: SAH model was induced by puncturing the internal carotid artery endovascular. The rats were randomly divided into four groups,including sham group(n=15), SAH group(n=15), Vehicle group(n=15), and MT group(n=15). The modeling process of sham group was same as SAH group, but do not puncture vessel. After successful modeling, rats of SAH group were given conventional feeding without any intervention, and rats of MT group were intraperitoneally injected with melatonin solution(60mg/kg)immediately while rats of Vehicle group were received the same volume of Vehicle(1% alcohol) as MT group. Each group of rats were raised in the same methods, environment and postoperative care. Evaluating neurobehavioral scores at 48 hours post-SAH, then we killed all rats to getspecimens of temporal lobe cortex and basal artery. Using hematoxylin-eosin(HE) staining to observe morphology of basal artery and immunohistochemical staining to test the expression of p38 MAPK, P53 in temporal cortex and basal artery wall, all the data obtained were performed statistical analysis with SPSS13.0 software. P<0.05 was considered statistically significant.Result: 1. Mortality: All rats of Sham group survived At 48 hours after operation. The overall mortality of SAH model rats was 48%. The rats of death primarily occur within 24 h after surgery in SAH group, Vehicle group or SAH+MT group. The mortality rates of three groups were 51.61%, 48.28%,and 42.31%, respectively. Compared with Sham group, the mortality rates of them were significantly increased(P<0.05). No statistical significance was seen between SAH group and Vehicle group(P>0.05), while Vehicle group and MT group had no significant difference in mortality rates(P>0.05).2. Neurobehavioral score: The higher the score, the more severe neurologic deficits was. The score in SAH group rats was significantly higher than Sham group at 48 hours post-SAH(P<0.01). There was no significant difference between SAH group and Vehicle group(P>0.05), but the score in MT group was lower than Vehicle group(P<0.05).3. Morphological of basal artery: In the Sham group, the basal arterial lumen was large, round or oval, smooth the blood vessel walls without thickening, its intima without folding, no crack, and the structure of endothelial cells remained intact. In SAH group and Vehicle group, the basal arterial walls thicken and its intima showed folding, even crack occasionally.The endothelial cells appeared swollen and the outer membrane appeared inflammatory cells infiltration. The inside diameter of basal arterial wereobviously shorter than Sham group(P<0.01), but there was no significant difference between the former two group(P>0.05). MT group showed the basal artery wall slightly thickened, intima slightly wrinkles without crack,slight swollen endothelial cells, and a small amount of inflammatory cells infiltration in the outer membrane. The inside diameter of basal arterial was markedly enlarged as compared with Vehicle group(P <0.01).4. The expression of p38MAPK: p38 MAPK main expression in the nucleus or cytoplasm. In the temporal lobe cortex, Sham group is a small amount of positive expression. Compared with the Sham group, p38 MAPK expression levels in the SAH group was significantly increased(P<0.01).There was no significant difference between SAH group and Vehicle group in p38 MAPK expression levels(P>0.05). However, MT group showed lower level expression than Vehicle group(P < 0.01). In the basal artery blood wall,Sham group show expression rarely. SAH group and Vehicle group appeared a large number of expression both in endometrium and the smooth muscle layer. There was no significant difference between them, but the two grope had obvious difference to compared with the Sham group(P<0.01). MT group showed lower level expression than Vehicle group(P <0.05).5. The expression of P53: P53 positive expression mainly in the nucleus,with occasional expressed in the cytoplasm. In the temporal lobe cortex,Sham group is a small amount of positive expression. Compared with the Sham group, p38 MAPK expression levels in the SAH group was significantly increased(P< 0.01). There was no significant difference between SAH group and Vehicle group in p38 MAPK expression levels(P>0.05). However, MT group showed lower level expression than Vehicle group(P < 0.01). In the basal artery blood wall, Sham group show expression rarely. SAH group andVehicle group appeared a large number of expression both in endometrium and the smooth muscle layer and significant higher than Sham group(P <0.01), but there was no significant difference between the former group(P>0.05). MT group showed lower level than Vehicle group(P < 0.01).Conclusions: 1. The rats suffering from SAH manifest neurologic deficits after the surgery, and this is the result of EBI following SAH. But melatonin treatment can significantly attenuate neurologic deficits of SAH model rats. It suggests that melatonin can attenuate EBI.2. What may be one of the pathogenesis about EBI following SAH is that SAH markedly increases the expression of p38 MAPK and P53 in the temporal lobe cortex.3. Basilar artery contraction within early period following SAH means that acute cerebral vasospasm has happened at post-SAH. We think it is the component of EBI and may be related to increased level of p38 MAPK and P53 in the basilar artery wall.4. Melatonin can attenuate EBI by inhibiting expression of p38 MAPK and P53 in cortex directly and inhibiting expression of p38 MAPK and P53 in blood vessel walls to alleviate the acute cerebral vasospasm indirectly.