Neuropeptide Y and autonomic nervous system

Neuropeptide Y (NPY) containing 6 amino acid residues belongs to peptides widely spread in the central and peripheral nervous system. NPY and its receptors play an extremely diverse role in the nervous system, including regulation of satiety, of emotional state, of vascular tone, and of gastrointestinal secretion. In mammals, NPY has been revealed in the majority of sympathetic ganglion neurons, in a high number of neurons of parasympathetic cranial ganglia as well as of intramural ganglia of the metasympathetic nervous system. At present, six types of receptors to NPY (Y₁–Y₆) have been identified. All receptors to NPY belong to the family of G-bound proteins. Actions of NPY on peripheral organs-targets are predominantly realized through postsynaptic receptors Y₁, Y₃–Y₅, and presynaptic receptors of the Y₂ type. NPY is present in large electrondense vesicles and is released at high-frequency stimulation. NPY affects not only vascular tone, frequency and strength of heart contractions, motorics and secretion of the gastrointestinal tract, but also has trophic effect and produces proliferation of cells of organs-targets, specifically of vessels, myocardium, and adipose tissue. In early postnatal ontogenesis the percent of the NPY-containing neurons in ganglia of the autonomic nervous system increases. In senescent organisms, this parameter decreases. This seems to be connected with the trophic NPY effect on cell-targets as well as with regulation of their functional state.