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目的观察局部应用胰岛素对老龄糖尿病(diabetes mellitus,DM)大鼠烫伤创面愈合的影响,探讨其可能的作用机制。方法SPF级Wistar老龄(12～24月龄)大鼠75只,雌雄不限,体重300～350g,随机分为3组,每组25只。A组为烫伤对照组,B组为DM烫伤对照组,C组为DM胰岛素治疗组。除A组外,B、C组大鼠经高脂、高蛋白、高糖饲养1个月后腹腔注射链脲佐菌素,建立老龄DM动物模型,同法饲养。DM模型制备8周后制备各组大鼠深Ⅱ度烫伤模型。A、B组创面局部注射灭菌生理盐水2mL,C组创面局部注射胰岛素0.1U,于伤后7、14、21d计算各组大鼠创面愈合率;伤后1、3、7、14、21d行HE染色观察,并检测创面组织糖含量、羟脯氨酸(hydroxyproline,HOP)含量,行CD34免疫组织化学染色观察并计算微血管密度(microvessel density,MVD)。结果伤后7、14、21d,A、C组创面愈合率明显高于B组,差异有统计学意义(P<0.05);A、C组间比较差异无统计学意义(P>0.05)。组织学观察见A组伤后21d,创面上皮基本上皮化;B组仍有大量坏死组织,创面未愈;C组创面上皮完全上皮化,上皮细胞分化较好,新生胶原较多。伤后1、3、7、14、21d A组创面组织糖含量明显低于B、C组,C组在伤后7、14、21d明显低于B组,比较差异均有统计学意义(P<0.05)。各时间点A、C组创面组织中HOP含量、MVD计数均明显高于B组,差异有统计学意义(P<0.05);A、C组间比较差异无统计学意义(P>0.05)。CD34表达:A组伤后7d呈+,14d呈++,21d呈+++;B组伤后14、21d呈+;C组伤后7d呈++,14、21d呈+++。结论局部应用胰岛素可促进创面胶原合成,增加创面的血管形成,加速老龄DM大鼠烫伤创面愈合。
Objective To investigate the effect of topical application of insulin on burn wound healing in aged diabetic mellitus (DM) rats and to explore its possible mechanism. Methods Seventy-five Wistar aged (12-24 months old) rats were randomly divided into 3 groups (n = 25). Group A was scalded control group, Group B was DM scald control group, Group C was DM insulin treatment group. Except group A, rats in groups B and C were fed with streptozotocin intraperitoneally 1 month after being fed with high fat, high protein and high glucose to establish an animal model of aging DM. After 8 weeks of DM model preparation, deep second degree scald model was made in each group. A, B group wound local injection of sterile saline 2mL, C group wound local injection of insulin 0.1U, 7,14,21d after injury in each group calculated wound healing rate of each group; 1,3,7,14,21 days after injury The contents of glucose and hydroxyproline (HOP) in the wound tissue were detected by HE staining. The microvessel density (MVD) was observed by CD34 immunohistochemical staining. Results The healing rates of wounds in groups A and C were significantly higher than those in group B at 7, 14 and 21 days after injury (P <0.05). There was no significant difference between groups A and C (P> 0.05). Histological observation showed that on the 21th day after injury in group A, the epithelial epithelial cells were basically epithelialized. There were still a large number of necrotic tissues in group B, and the wounds did not heal. In group C, epithelial cells were completely epithelialized and epithelial cells differentiated well. At 1, 3, 7, 14 and 21 days after injury, the content of glucose in wounds in group A was significantly lower than those in groups B and C, and the levels of glucose in group C were significantly lower than those in group B at 7, 14 and 21 days after injury (P <0.05). The contents of HOP and MVD in wounds of groups A and C at each time point were significantly higher than those in group B (P <0.05). There was no significant difference between groups A and C (P> 0.05). The expression of CD34 in group A was + 7 days after injury, +++ on day 14 and +++ on day 21; + 14 and 21 days after injury in group B was +; on day 7, group C was +++ on day 7 and +++ on day 14 and 21. Conclusion Topical application of insulin can promote wound collagen synthesis, increase blood vessel formation and accelerate the healing of scalded wounds in aged DM rats.