Distribution of the neuropeptide galanin in the cat heart and coexistence with vasoactive intestinal peptide, substance P and neuropeptide Y.

The neuropeptide galanin (GAL) has been detected in the peripheral and central nervous systems. However, little is known about its distribution and localization in heart, and the possible coexistence of GAL with other neuropeptides in the heart is not established. The present immunocytochemical study describes the distribution of GAL in nerves of the feline heart and its colocalization with vasoactive intestinal peptide (VIP), substance P (SP), and neuropeptide Y (NPY). GAL-like immunoreactivity was widely distributed in the atrial and ventricular myocardium and around coronary arteries. Colocalization of GAL with VIP, SP and NPY was observed in many nerve fibers. Further, GAL and NPY were colocalized in nerve cell bodies of intracardiac ganglia. Since these neuropeptides have been found to be associated with sensory and autonomic innervation in the heart, the present findings provide evidence that GAL is shared by functionally different neuronal populations in the heart and that GAL may participate in controlling cardiac function by combined action with other neuropeptides.