Expression of nerve growth factor and sympathetic neural remodeling after myocardial infarction in type II diabetic rats

AIM: To explore the alteration of the expression of nerve growth factor (NGF) and sympathetic neural remodeling after myocardial infarction in type II diabetic rats. METHODS: Samples were obtained from the peri-infarcted area, ventricular septum and right ventricle (RV) in infarcted diabetic rats. Using immunohistochemistry and computerized image-processing technique, expressions of NGF protein and sympathetic innervation were examined in different groups (blank, diabetic, infarcted, and infarcted diabetic, respectively). RESULTS: In the diabetic group, expressions of NGF protein were lower than those in the blank group (P<0.05) and those in the infarcted diabetic group (P<0.01). The density of sympathetic nerves was also lower than in the infarcted diabetic group (P<0.01). In the infarcted group, expressions of NGF protein and density of sympathetic nerves were both higher than in the blank group (P<0.05, P<0.01) and those in the infarcted diabetic group (P<0.05, P<0.01). NGF protein expression was correlated with sympathetic innervation in the peri-infarcted area, RV and septum in infarcted group (P<0.05). CONCLUSION: Diabetes mellitus decreases the expression of NGF protein in cardiomyocytes but increases sympathetic reinnervation and hyperinnervation, indicating that it may not be NGF but some other factor that plays a crucial role in post-infarct neural remodeling.