| Wound healing is a complicated and ordered biological course,which includes hemostasis of wound,inflammatory reaction,proliferation,differentiation, epithelization and migration of cell,and synthesis,maturation and remodeling of matrix.The nutrition of skin is mainly provided by microcirculation. During the course of wound healing,the tissue needs sufficient nutrition and the energy metabolism is strengthened.So the favorable microcirculation function is vital for the normal wound healing.Circulating insulin(from Latin insula,"island") is produced by beta cells in the Islets of Langerhans in the pancreas and has systemic effects.Previous studies have shown that insulin has a wide range of biological effects.Insulin can promote protein synthesis and correct the negative nitrogen balance.In clinical practice,insulin is mainly used to treat for the diabetes and ischemic cerebrovascular disease.Some studies have shown that insulin may participate in the regulation of inflammatory response during wound healing,insulin released locally in tissues can promote endothelial cell division.In recent years,the effects of insulin and blood glucose control on thermal burn wounds have been reported in some studies.It is noteworthy that some authors have reported that local application of insulin may promote wound healing.In addition,there are also individual reports abroad about insulin gel for the treatment of skin ulcers in rats. However,the molecular mechanisms of local application of insulin insulin are largely unknown.The lack of this knowledge hampers the development of rational and efficient strategies to promote wound healing.After the local application of insulin in experiment rat model of chronic skin wounds,wound healing,blood glucose in rats,wound angiogenesis and changes in VEGF levels are observed.Our experiment is divided into 3 sections.Fourty five animals were randomly divided into control group(vaseline gauze A),4 units group(group B) and 8 units group(group C).1.On the 8th day after surgery,five rats of each group were selected.Wounds were covered with aseptic transparent glass slide,drawing along the edge of the wound with a marker pen.Copy with a uniform thickness of the transparent plastic film and cut the wound pattern.The quality of transparent plastic film blueprint was measured in one ten thousandth of electronic analytical balance. Convert the quality into the corresponding wound area and calculate the rate of wound healing in each group.The rate of wound healing =(original wound area -the remainder of the wound area)/original wound area.Results:The original wound area was 3.14±0.10 cm~2.The wound area of group A was 2.5±0.13 cm~2. The wound area of group B was 2.05±0.09 cm~2.The wound area of group C was 1.98±0.13 cm~2.The wound area of group C was statistically significant different from that of group A and group B(P＜0.05);while there was not difference between group B and group C(P＞0.05).The rate of wound healing of group A was 20.38±4.06%,The rate of wound healing of group B was 34.71±2.89%,The rate of wound healing of group C was 36.94±5.41%,The rate of wound healing of group C was statistically significant different from that of group A and group B(P＜0.05);while there was not difference between group B and group C(P＞0.05).2.On the 8th day after surgery,five rats of each group were selected.Blood sugar was measured.Wound tissue in the center and the periphery(diameter 1 cm, thickness 3 mm) was obtained for HE staining.The total protein and wound capillaries was observed.Results:The blood sugar of the animals was 10.63±0.24 mmol/L.he blood sugar of group A was 10.86±0.38 mmol/L.The blood sugar of group B was 9.84±0.58 mmol/L.The blood sugar of group C was 9.69±0.43 mmol/L.The blood sugar of group C was statistically significant different from that of group A and group B(P＜0.05);while there was not difference between group B and group C(P＞0.05).The increase of wound capillary was more significant in group B and group C compared with group A,there was not difference between group B and group C(P＞0.05).3.On the 8th day after surgery,five rats of each group were selected.Blood sugar was measured.Wound tissue in the center and the periphery(diameter 1 cm, thickness 3 mm) was obtained for RT-PCR.Results:Compared with the group B and group C,the mRNA expression of VEGF in group A was significant upregulated.Although the VEGF mRNA expression of Group C was slightly higher than that of Group B,Conclusion:(1) In wound healing experiment rat model of chronic skin wounds,the external application of insulin can increase the rate of increase.(2) After the external application of insulin,the blood sugar have a slightly decline.(3) Insulin can promote wound healing by increasing the number of capillaries and upregulating the VEGF mRNA expression.
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