EXOCYTOSIS FROM A SINGLE-RAT CHROMAFFIN CELL BY CHOLINERGIC AND PEPTIDERGIC NEUROTRANSMITTERS

Citation
Ps. Chowdhury et al., EXOCYTOSIS FROM A SINGLE-RAT CHROMAFFIN CELL BY CHOLINERGIC AND PEPTIDERGIC NEUROTRANSMITTERS, Neuroscience, 59(1), 1994, pp. 1-5
Citations number
23
Categorie Soggetti
Neurosciences
Journal title
ISSN journal
03064522
Volume
59
Issue
1
Year of publication
1994
Pages
1 - 5
Database
ISI
SICI code
0306-4522(1994)59:1<1:EFASCC>2.0.ZU;2-X
Abstract
Secretion of catecholamines from chromaffin cells is mediated by choli nergic and peptidergic neurotransmitters.(3,11,14) The cholinergic tra nsmitter acetylcholine activates both nicotinic and muscarinic recepto rs to trigger catecholamine secretion in rat adrenal medulla.(17) Vaso active intestinal polypeptide (VIP) has been identified as the peptide rgic transmitter in rat adrenal medulla and may also be the non-cholin ergic transmitter in bovine adrenal.(18,23) Pituitary adenylate cyclas e activating polypeptide (PACAP), a VIP-like secretin peptide, is also found in the adrenal,(5) and is a potent secretagogue.(7,21) Thus, PA CAP may be another peptidergic transmitter at the adrenal synapse.(19) A most intriguing property of rat chromaffin cells is that stimulatio n of nicotinic, muscarinic, VIP or PACAP receptors are each able to pr oduce robust catecholamine secretion on their own.(11-13,21) This rais es the question of whether a single chromaffin cell can respond to eac h of the above agonists or whether the secretion is due to subpopulati ons of chromaffin cells. This issue was addressed by using electrochem ical techniques to monitor exocytosis from individual chromaffin cells in culture.(2,9,22) We demonstrate that acetylcholine, nicotine, musc arine, VIP and PACAP are each able to evoke catecholamine secretion fr om a single chromaffin cell. Some cells only responded to acetylcholin e. Furthermore, each agonist produced a distinct pattern of exocytosis . Muscarine-evoked secretion exhibited a latency of 0.5-2 s, but exocy tosis persisted up to 30 s following 500 ms stimulation. Nicotine prod uced an immediate response which usually ended within 10 s. The secret ory pattern following acetylcholine appeared to be the sum of the nico tinic and muscarinic patterns, showing both rapid onset and longer dur ation. The unique property of peptidergic stimulation was that a brief exposure caused exocytosis to persist for up to 2 min. Like muscarine , peptides exhibited latency in producing exocytosis. These findings s upport the idea that the interactive control of catecholamine secretio n by nicotinic, muscarinic and peptidergic receptors occurs at the lev el of single cells.