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Cellular electrophysiological actions of alpha‐melanocyte‐stimulating‐hormone (MSH) on neurons in the raphe pallidus (RPa) and adjacent area
Author(s) -
Gu Yan,
Fan Wei
Publication year - 2007
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.21.5.a460-b
Subject(s) - electrophysiology , neuroscience , brainstem , melanocortin , medicine , chemistry , reversal potential , endocrinology , biology , patch clamp , hormone
The central melanocortin system plays a critical role in energy homeostasis. The RPa contains important sympathetic premotor neurons that regulate thermogenesis. While α‐MSH fibers and melanocortin 4 receptor (MC4R) are expressed in the RPa and adjacent area, the effect of α‐MSH on the RPa neurons is unknown. We assessed the functional actions of α‐MSH on the RPa neurons using neonatal rat brainstem slice preparations. Under a loose‐patch extracellular recording, bath applied α‐MSH (400 nM) caused a rapid and reversible increase in firing rate by 2.17 fold in 46.4 % of the RPa neurons tested (13 out of 28 neurons), and a decrease in firing rate in 21.4% of the neurons (6 out of 28) while 32.1% of the neurons (9 out of 28) were not affected. α‐MSH (400 nM) increased the firing rate in 53.3% of the neurons (8 out of 15) by 2.2 fold in the presence of kynurenic acid (2mM), picrotoxin (100μM) and strychnine (10μM) while 7 neurons did not respond to α‐MSH. Under whole cell current clamp recordings, 400nM α‐MSH depolarized the cells in 6 out of 14 neurons (p<0.05). The depolarizing effect of α‐MSH remained in the presence of 1μM TTX (n=4). These data indicate a complexity of electrophysiological responses of the RPa neurons to α‐MSH and provide a cellular electrophysiological basis to understand the potential complex functional implication of the RPa MC4R signaling in the regulation of energy balance. Supported by NIH grant DK62179 (WF).