Myocardial infarction induces sympathetic hyperinnervation via a nuclear factor-κB-dependent pathway in rabbit hearts.

Cardiac sympathetic hyperinnervation after myocardial infarction (MI) is associated with a high incidence of lethal arrhythmia. However, the mechanisms of nerve sprouting induced by MI are unclear. In this study, we showed a nuclear factor-κB (NF-κB) signaling pathway involved in cardiac sympathetic hyperinnervation after MI in rabbit hearts. An MI model was induced by ligation of the coronary artery in rabbits, which were then euthanized after 7 days. Rabbits with MI showed sympathetic hyperinnervation, as revealed by immunohistochemical analysis of the density of nerve fibers positive for growth-associated protein 43 (GAP43) and tyrosine hydroxylase (TH). Using western blot and real-time RT-PCR techniques, we found that MI was associated with activation of NF-κB signaling and consequent upregulation of nerve growth factor. Intravenous administration with the NF-κB inhibitor pyrrolidine dithiocarbamate (100mg/kg/day) inhibited NF-κB activation and ameliorated sympathetic hyperinnervation after MI. These results suggest that cardiac nerve sprouting after MI is associated in part with NF-κB activation and may be one of the mechanisms responsible for sympathetic hyperinnervation induced by MI.