@article {Hexum61, author = {T D Hexum and J Zheng and J Zhu}, title = {Neuropeptide Y inhibition of nicotinic receptor-mediated chromaffin cell secretion.}, volume = {271}, number = {1}, pages = {61--66}, year = {1994}, publisher = {American Society for Pharmacology and Experimental Therapeutics}, abstract = {Neuropeptide Y (NPY), a widely distributed peptide with varied activities, inhibits nicotinic receptor-induced [3H]norepinephrine ([3H]NE) secretion from bovine chromaffin cells. The secretion produced by membrane depolarization with high KCl concentrations or veratridine is not inhibited. Fragments of NPY, such as NPY18-36, are potent inhibitors of [3H]NE secretion, whereas [Leu31,Pro34]-NPY and peptide YY have no effect. The response to NPY18-36 is not sensitive to pertussis toxin pretreatment of chromaffin cells. NPY fragments also inhibit nicotinic receptor-induced 45Ca++ influx but not that induced by KCl or veratridine. The rank orders of potency for inhibition of [3H]NE secretion and 45Ca++ influx are the same: NPY18-36 \> or = NPY26-36 \> NPY13-36. NPY and NPYfree acid are weak inhibitors of secretion but not 45Ca++ influx. Moreover, the IC50s for NPY18-36 inhibition of [3H]NE secretion and 45Ca++ influx are comparable, 1.4 x 10(-6) M and 0.9 x 10(-6) M, respectively. Regression analysis produced a correlation coefficient of 0.9842 (P \< .0001). It was concluded that NPY inhibits [3H]NE secretion by a modification of the nicotinic receptor-mediated increase in Ca++ influx. The characterization of the response suggests that the NPY effect is mediated by a previously undefined NPY receptor subtype that was designated Y4.}, issn = {0022-3565}, URL = {https://jpet.aspetjournals.org/content/271/1/61}, eprint = {https://jpet.aspetjournals.org/content/271/1/61.full.pdf}, journal = {Journal of Pharmacology and Experimental Therapeutics} }