Enhanced expression of cardiac nerve growth factor and nerve sprouting markers in rats following gastric perforation: the association with cardiac sympathovagal balance.

Endotoxemia and/or systemic inflammation may lead to disturbances in the cardiac autonomic nervous system and consequent arrhythmia. The underlying mechanism remains unclear. Therefore, we investigated the expression of nerve growth factor (NGF) and its association with cardiac sympathovagal balance in a rodent model of self-limited peritonitis. Male Wistar rats were randomized into the following groups: normal control, sham, gastric perforation (GP), and GP treated with methylprednisolone. Cardiac expression of NGF, growth-associated protein 43 (GAP43), along with other nerve markers were evaluated at several time points (6 h to 2 weeks) after GP. An autoregressive process was performed on each detrended electrocardiogram to calculate the heart rate power spectrum. Compared with the normal control and sham groups, expression of NGF was significantly elevated for 1 week after GP. We also found the up-regulated GAP43 and tyrosine hydroxylase protein levels in the GP group, which persisted after recovery from peritonitis. Gastric perforation caused a biphasic change in the ratio of low-frequency to high-frequency power (an index of sympathovagal balance), with an initial decrease followed by recovery at 24 h. Increased NGF and cardiac sympathetic marker expression were temporally associated with the restoration of the cardiac sympathovagal balance. Methylprednisolone abrogated the NGF up-regulation induced by GP and delayed the resumption of sympathovagal balance. We conclude that GP resulted in up-regulation of cardiac NGF, GAP43, and tyrosine hydroxylase expression that coincided with recovery of cardiac sympathovagal balance. Moreover, methylprednisolone can effectively block GP-induced NGF up-regulation.