Expression of nerve growth factor receptors after myocardial infarction in rats

AIM:Nerve growth factor (NGF) regulates myocardial sympathetic innervation and induces sympathetic nerve hyperinnervation after myocardial infarction. Its neutrophic effects by binding to specific cell surface receptors, including the high-affinity receptor tyrosine kinase A (TrkA) and the NGF low-affinity receptor P75NTR. However, it is unclear whether TrkA and P75NTR are altered after acute myocardial infarction. The aim of this study was to determine the dynamic change of NGF receptor expression from 1 day to 30 days after myocardial infarction in the rat. METHODS: Rats were subjected to MI and killed 1, 7, 30 days after MI, sham-operated rats were considered as control. TrkA and P75NTR mRNA expression and protein levels in the infarcted border myocardium were measured by real-time PCR and Western blot. RESULTS: We found that after MI, both P75NTR mRNA expression and protein levels showed no significant changes when compared with control group at all time points, whereas TrkA expression decreased at day 7 after MI and continued to decrease at day 30 (P<0.05). CONCLUSION: A specific temporal pattern of TrkA/p75NTR occurred in post-MI rats, and the p75NTR may not be crucial, mediating sympathetic innervation after MI.