Neuroprotective Mechanism Of NBP Preconditioning In Cerebral Ischemia Reperfusion Injury On Sprague-Dawley Rats

Objective: Applying the method of NBP preconditioning, use focal ischemia reperfusion model of Sprague-Dawley rat, through observing neurologic impairment, measuring cerebral infarction volume, detecting the expression of caspase-3 and Bcl-2 levels, to study neuroprotective mechanism of NBP preconditioning in cerebral ischemia reperfusion injury on SD rats.Methods: Forty-eight healthy adult male SD rats, weight 200-250g, clearly class, provided with room temperature, take the meal and water freely. They were randomly divided into the sham-operative group, focal cerebral ischemia reperfusion group and NBP preconditioning group, 16 for each group. The NBP preconditioning group was given gastric lavage(200mg/kg/d)for 5 days with NBP solvent(NBP soft capsule dissolved with 0.9% Nacl, shaked before use), once a day.the sham-operative group and focal cerebral ischemia reperfusion group was also given gastric lavage with the same volume 0.9% Nacl for 5 days, once a day.Using the Zea-Longa method to established the middle cerebral artery occlusion(MCAO)model, sutures pluged in 18mm, then ischemia for 2 hours, reperfusion for 24 hours(except the sham-operative group).The neurological scores were made on Zea Longa 5-point scale, when reach the reperfusion point, all removed brains were stained respectively with:(1)2% Triphenyl tetrazalium chloride(TTC), the volume of infarctiion was measured by the photoshop image analysis system;(2)Hematoxylin-eosin(HE)staining to observe the cerebral pathomorphology; (3)Use immunohisto-chemistry technology to detected the caspase-3, bcl-2 levels. Results:1.The neurologic impairment score: The sham-operative group had no neurologic impairment, the score is zero; compared with the sham-operative group, the neurologic impairment of focal cerebral ischemia reperfusion group and NBP preconditioning group is obviously (P<0.01); compared with focal cerebral ischemia reperfusion group, the neurological scores of NBP preconditioning group are alleviated (P<0.05).2.The infarction volume: The sham-operative group had no infarction area, showed red color; compared with the sham-operative group, focal cerebral ischemia reperfusion group and NBP preconditioning group had obviously infarction area, showed white colo(rP<0.01); compared with focal cerebral ischemia reperfusion group, the infarction volume of NBP preconditioning group are reduced(P<0.05).3.Hematoxylin-eosin(HE)staining: The sham-operative group had no infarction area and evident pathological change, showed normal cerebral orgnazations. The nerve cells in focal cerebral ischemia reperfusion group shrank and degenerated, apparent edema between tissues and vacuolization. In NBP preconditioning group, the number of nerve cells which appeared degeneration and necrosis reduced compared with focal cerebral ischemia reperfusion group, inter-tissue edema and vacuolization relieved also in NBP preconditioning group.4.Immunohistochemistry technology result:(1)The expression of caspase-3: In sham-operative group, a few of caspase-3 positive cells can be seen; compared with the sham-operative group, the expression of caspase-3 in focal cerebral ischemia reperfusion group and NBP preconditioning group are obviously(P<0.01); compared with focal cerebral ischemia reperfusion group, the number of caspase-3 positive cells in NBP preconditioning group are reduced(P<0.05).(2)The expression of bcl-2: In sham-operative group, a few of bcl-2 positive cells can be seen; compared with the sham-operative group, the expression of bcl-2 in focal cerebral ischemia reperfusion group and NBP preconditioning group are obviously(P<0.01); compared with focal cerebral ischemia reperfusion group, the number of bcl-2 positive cells in NBP preconditioning group are reduced(P<0.05).Conclusions:1.Caspase-3 and bcl-2 may be take part in the process of cerebral ischemia reperfusion injury, which caspase-3 promote nerve cell apoptosis, and bcl-2 restrain nerve cell apoptosis.2.Use the method of NBP preconditioning may reduce the injury caused by cerebral ischemia reperfusion of SD rats, lighten the neurologic impairment, lessen the infarction volume, decreased the number of nerve cells which appeared degeneration and necrosis, and reduced the number of caspase-3 which can promote nerve cell apoptosis, increased the number of bal-2 which can restrain nerve cell apoptosis.3.NBP can reduce transient ischemic attack, has neuroprotective mechanism in cerebral ischemia reperfusion injury.