Development of neuropeptide Y-mediated heart innervation in rats

© 2015 Elsevier Ltd. Neuropeptide Y (NPY) playsa trophic role in the nervous and vascular systems and incardiac hypertrophy. However, there i s no report concerning the expression of NPY and its receptors in the heart during postnatal development. In the current study, immunohistochemistry and Western blot analysis was used to label NPY, and Y1R, Y2R, and Y5R receptors in the heart tissue and intramural cardiac ganglia from rats of different ages (newborn, 10 days old, 20 days old, 30 days old, 60 days old, 1 year old, and 2 years old). The obtained data suggest age-dependent changes of NPY-mediated heart innervation. The density of NPYimmunoreactive (IR) fibers was the least in newborn animals and increased in t h e first 20 days of life. In t he atria of newborn and 10-day-old rats, NPY-IR fibers were more abundant compared with t h e ventricles. The vast majority of NPY-IR fibers also contained tyrosine hydroxylase, a key enzyme in catecholamine synthesis. The expression of Y1R increased between 10 and 20 days oflife. Faint Y2R immunoreactivity was observed in the atria and ventricles of 20-day-old and older rats. In contrast, the highest level of the expression of Y5R was found in newborn pups comparing with more adult rats. All intramural ganglionic neurons were also Y1R-IR and Y5R-IR and Y2R-negative in all studied animals. Thus, the increasing of density of NPY-containing nerve fibers accompanies changes in relation of different subtypes of NPY receptors in the heart during development