Effect Of Zn-metallothionein On Wound Healing Of Rats Following Deep Grade Ⅱ Skin Burns

Background:The burn of Secondary and Small area andⅡdegree are the most in clinic.The pristine minicirculation of wound surface region and the anaphase capillary vessel form of wound surface have momentous contribution with the wound surface ofⅡdegree diversify. The pristine wound surface is in a course of dynamic change, generally,the wound surface will to deepen gradually because of ischemia and hypoxia and excessive inflammatory reaction. Burn induce oxidative stress,and excess oxygen-derived free radicals provoke the degression of capability of the the recovery cells migration and proliferation and dyssynthesis of extracellular matrix, and through demolish the keratosic epithelial cell and the osmolarity of lumina and the metabolism of collagen lead to the disturbance of wound healing.so,there is necessity to develop a kind of burn drugs for external with inhibit the oxidative stress reaction of deep gradeⅡskin burns and improve the microcirculation of the wound surface and lessen the rather too thick inflammatory reaction and promote the burn wound healing,provide a original therapeutic tool and nursing strategy.Zn-metallothionein(Zn-MT) is low molecular number in-zymoprotein with multi- hydrosulfide and bivalence metal and 7 zn-ion. It is proved by a series of researchs that MT have activity to discard oxygen-derived free radicals and counteract lipid peroxidation. In the process of wound healing,MT is discocerd to effect and accommodate the intention with some cell factors. At present,the research is only about the effection of consumed oxygen and the avtivity of succinodehydrogenase,there is no research about whether Zn-MT can inhibit the oxidative stress reaction of raw surface and improve minicirculation and prevent thrombus form and forbid the pristine burn raw surface to deepen.Object:The study establish the model of deep gradeⅡskin burn rat,observe Zn-MT on the depressant effect of the oxidative stress reaction and the influence of the microcirculation of the wound surface.Study the action of Zn-MT in the deep gradeⅡskin burn wouund healing,and from the angle of the inhibition of the oxidative stress reaction to approach the possible mechanism of action and provide a original therapeutic tool and nursing strategy of burn raw suface.Method:1.A total of 78 healthy male Wistar rats were randomly divided into Zn-MT group(experimental group,EG) and saline group(control group,CG), with 36 rats per group,and normal control group with 6 rats in it. Back of rats were stored in water at 98℃for 8 s to establish 15% deep grade II burning models in EG and CG, and were administered after burn instantly. Zn-MT at the concentration of 1×10-5mol/L was immediately administrated in theEG,while saline was used in the saline group. The bandage was changed every 4 hours on the first day, every 8 hours on the second and third days, and then every day till the wound surface was healed.2.At the observation was performed at six different time points,including 12h,24,48 h,7d,14d and 21d, with 6 rats at each time point.3.The condition of wound healing were observed by hematoxylin and eosin stain,the activity of SOD of wound tissue were measured by the method of xanthine oxidoreductase, the content of MDA of wound tissue were measured by the method of thio- barbituric acid,the microvessel density and the content of VEGF were measured by the method of immunohistochemistry staining,the content of HYP were measured by the method of chloramine T,the the content ofⅠandⅢcollagen were were measured by the method of immunohistochemistry staining.Results:1.The wound healing rate increased significantly in both EG and CG as the time passed(P<0.01).Compared with CG,the wound healing rate of EG increased much more sharply and were markedly higher than those of CG on postinjury 7d,14d,18d,21d(P <0.01).2.Both wound tissue MVD value showed a tendency of increase on postinjury 7d,14d,18d,21d(P<0.01),Compared with CG, the wound tissue MVD value of EG increased much more sharply and were markedly higher than those of CG(P<0.01).3.The VEGF contents in wound tissue of both groups were not showed significant deviation compared with normal control group on postinjury 12h(P>0.05).Since then, both contents showed a tendency of increase. Compared with CG, the VEGF contents in wound tissue of EG increased much more sharply and were markedly higher than those of CG on postinjury 24h,48h,7d,14d(P<0.01). Both contents showed a tendency of decrease,and there were showed significant deviation compared with normal control group and between two groups on postinjury 21d(P<0.01).4.The SOD activity in wound tissue of both groups droppedd with normal control group on postinjury 12h,24h,48h,7d,14d(P<0.01). The SOD activity in wound tissue of CG rose slowly,correspondingly,that of EG near to the normal level slightly on postinjury 21d.it could be seen obviously that SOD activity in wound tissue of EG went much higher than that of CG on postinjury 12h,24h,48h,7d,14d(P<0.01).5.The MDA contents in wound tissue of both groups were not showed significant deviation compared with normal control group on postinjury 12h(P>0.05).The MDA contents in wound tissue of both groups droppedd with normal control group on postinjury 24h,48h(P<0.01),but that of EG presented a less increasing tendency(P>0.05).On postinjury 7d, the MDA contents in wound tissue of both groups decreased,but that of EG presented a more decreasing tendency(P>0.05). On postinjury 14d,21d, the MDA contents in wound tissue of both groups decreased,and there were not showed significant deviation compared with normal control group(P>0.05).6.The HYP value in in wound tissue of both groups were showed significantly advanced compared with normal control group on postinjury 48h,7d(P>0.05),and compared with CG,the HYP value in wound tissue of EG increased much more sharply and were markedly higher than those of CG(P<0.01). The HYP value in wound tissue of EG were higher significantly than that of CG,but there were not showed significantly advanced compared with normal control group on postinjury 14d(P<0.01). The HYP value in wound tissue of EG were higher significantly than that of normal control(P<0.01),but there not showed significantly advanced between CG and normal control group on postinjury 21d(P <0.05).7.The gray scale percentage ofⅠcollagen andⅢcollagen were higher significantly than that of CG on postinjury 48h,7d,14d,21d(P<0.01).And the gray scale percentage ofⅠcollagen were showed a increaseing tendency as the time passed; the gray scale percentage ofⅢcollagen were showed a decreasing tendencyas the wound healing.Conclusions:1.Zn-MT can marked shorten the time of wound surface epithelization, promote formation of wound surface micrangium, amendment the minicirculation of burn wound surface,encourage the capillary vessel form.2.Zn-MT can marked increase synthesis and releasing of VEGF of deepⅡdegree wound surface tissue to accommodate proliferation and migration of vascular endothelial cell and increase the permeability of capillary vessel to encourage the wound healing.3.Zn-MT can marked decrease the analosis of the wound tissue SOD activity and decrease the MDA contents in wound tissue to inhibit lipid peroxidation and protect the wound surface and lipid and albumen of cytolemma.The contribution of clearance oxygen free radical and lipid peroxidation materiae is one of mechanisms of inhibit lipid peroxidation.4.Zn-MT can release zinc to wound surface, through regulate metabolism of zinc to get the destination of supplementing zinc to the wound tissue is one of mechanisms of deepⅡdegree wound healing.5.Zn-MT can promote formation and metabolism of collagen,increase form of epacme,provide the frame of the anaphase massive proliferation of keratinocyte and migrate to the wound surface, shorten the time of wound surface epithelization, encourage the paturity of wound surface.