Introduction: Myocardial infarction (MI) results in cardiac nerve sprouting in the myocardium. Whether or not similar neural remodeling occurs in the stellate ganglia (SGs) is unknown. We aimed to test the hypothesis that MI induces bilateral SG nerve sprouting.
Methods: Acute MI was created by coronary artery ligation in rabbits (n=12). Serum nerve growth factor (NGF) level was measured by enzyme-linked immunosorbent assay. The hearts and bilateral SGs were harvested for immunohistochemistry after 1 week in six rabbits and after 1 month in six rabbits. Immunostaining for tyrosine hydroxylase (TH), growth-associated protein 43 (GAP43), choline acetyltransferase (ChAT), and synaptophysin (SYN) was performed to determine the magnitude of nerve sprouting. Tissues from six normal rabbits were used as controls. Nerve density was determined by computerized morphometry.
Results: Myocardial infarction results in increased serum NGF levels at 1 week (1519.8±632.2 ng/ml) that persist up to 1 month (1361.2±176.3 ng/ml) as compared to controls (89.6±34.9 ng/ml) (P=.0002 and P=.0001, respectively). Immunostaining demonstrated nerve sprouting and hyperinnervation in both SGs after MI. The nerve densities (μm(2)/ganglion cell) in SG 1 week after MI and 1 month after MI and those in control groups, respectively, were as follows: GAP43: 278±96, 225±39, and 149±57 (P=.01); SYN: 244±152, 268±115, and 102±60 (P=.02); TH: 233±71, 180±50, and 135±68 (P=.047); ChAT: 244±100, 208±46, and 130±41 μm(2)/cell (P=.01).
Conclusions: Myocardial infarction increases serum NGF levels and induces nerve sprouting and hyperinnervation in bilateral SGs for at least 1 month after MI. The hyperinnervation includes both adrenergic axons and cholinergic axons in the SG.
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