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Glutamatergic Input to the Lateral Hypothalamus Stimulates Ethanol Intake: Role of Orexin and Melanin‐Concentrating Hormone
Author(s) -
Chen YuWei,
Barson Jessica R.,
Chen Aimee,
Hoebel Bartley G.,
Leibowitz Sarah F.
Publication year - 2013
Publication title -
alcoholism: clinical and experimental research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.267
H-Index - 153
eISSN - 1530-0277
pISSN - 0145-6008
DOI - 10.1111/j.1530-0277.2012.01854.x
Subject(s) - cnqx , endocrinology , medicine , chemistry , zona incerta , ampa receptor , lateral hypothalamus , nmda receptor , hypothalamus , antagonist , nociceptin receptor , glutamate receptor , melanin concentrating hormone , orexin , neuropeptide , biology , receptor , opioid , opioid peptide
Background Glutamate ( GLUT ) in the lateral hypothalamus ( LH ) has been suggested to mediate reward behaviors and may promote the ingestion of drugs of abuse. This study tested the hypothesis that GLUT in the LH stimulates consumption of ethanol ( EtOH ) and that this effect occurs, in part, via its interaction with local peptides, hypocretin/orexin ( OX ), and melanin‐concentrating hormone ( MCH ). Methods In Experiments 1 and 2, male S prague‐ D awley rats, after being trained to drink 9% EtOH , were microinjected in the LH with N ‐methyl‐ d ‐aspartate ( NMDA ) or its antagonist, D ‐ AP 5, or with alpha‐amino‐5‐methyl‐3‐hydroxy‐4‐isoxazole propionic acid ( AMPA ) or its antagonist, CNQX ‐ds. Consumption of EtOH , chow, and water was then measured. To provide an anatomical control, a separate set of rats was injected 2 mm dorsal to the LH . In Experiment 3, the effect of LH injection of NMDA and AMPA on the expression of OX and MCH was measured using radiolabeled in situ hybridization ( ISH ) and also using digoxigenin‐labeled ISH , to distinguish effects on OX and MCH cells in the LH and the nearby perifornical area ( PF ) and zona incerta ( ZI ). Results When injected into the LH , NMDA and AMPA both significantly increased EtOH intake while having no effect on chow or water intake. The GLUT receptor antagonists had the opposite effect, significantly reducing EtOH consumption. No effects were observed with injections 2 mm dorsal to the LH . In addition to these behavioral effects, LH injection of NMDA significantly stimulated expression of OX in both the LH and PF while reducing MCH in the ZI , whereas AMPA increased OX only in the LH and had no effect on MCH . Conclusions Glutamatergic inputs to the LH , acting through NMDA and AMPA receptors, appear to have a stimulatory effect on EtOH consumption, mediated in part by increased OX in LH and PF and reduced MCH in ZI .