Effects Of Dexmedetomidine On Nerve Functions In Subarachnoid Hemorrhage Model Rats

Objective: To evaluate the changs of the neurologic behavior and neuroprotection by different dose of DEX in subarachnoid hemorrhage model rats.Methods: Forty SD rats,both male and famle,aged 3 months,weighing250-300 g,were randomly divided into 5 groups(n=10 each): sham operation group(group C);SAH group(group C);low dose of dexmedetomidine group(group D1),medium dose of dexmedetomidine group(group D2)and high dose of dexmedetomidine group(group D3).SAH was induced by injecting 1ml/kg artery blood into the cisterna magna.After SAH immediately,in group D1-3,dexmedetomidine was intravenously infused for 2 h at a rate of2.5 ?g·kg-1·h-1,5 ?g·kg-1·h-1 and 10?g·kg-1·h-1.while normal saline 1.5ml/h were given instead of dexmedetomidine in group C and group S.After all,all the rats fed 48 h in original zones.The neurologic behavior scores were measured in five rats of each group after 48 h.Then rats were sacrificed for determination of wet to dry weight ratio.Additional five rats of each group were sacrificed after 48 h.The brain was removed for pathologic examination the expression of TNF,Bax and Bcl-2 in hippocamus were detected with light microscope..Results:Compared with group C,the neurologic behavior scores and wet to dry weight ratio were significantly increased,S and D1-3 groups(P < 0.05).Compared with group S,the neurologic behavior scores were decreased,D2-3groups(P < 0.05),and no significant change was found in parameters mentioned above in group D1(P > 0.05).wet to dry weight ratio were increased in group D3(P < 0.05),and no significant change was found in parameters mentioned above in group D1-2.Compared with group C,serious pathological changes were significantly attenuated,in S and D1-3 groups(P < 0.05).Hippocampal pyramidal cells arranged scattered and pyramidal nucleus concentrated,deeply stained,edema in group S.Compared with group S,The changes were gradually reduced in D1-3 groups.Compared with group C,S and D1-3 groups were thicker and had a significiant cerebral vasospasm.Compared with group S,D1-3 groups were gradually thinner.Compared with group C,the expression of TNF,Bcl-2 and Bax was up-regulated in S and D1-3 groups(P<0.05).Compared with group S,the expression of TNF and Bax were down-regulated in D2 and D3 groups(P<0.05),and no significant change was found in parameters mentioned above in group D1(P>0.05).The expression of Bcl-2 were up-regulated gradually in D1-3 groups(P<0.05).Conclusions: The mechanism by which dexmedetomidine have neuroprotective effects in rats subjects to SAH is related to inhibition of apoptosis and reduction of inflammatory responses.