Glutamatergic Input to the Lateral Hypothalamus Stimulates Ethanol Intake: Role of Orexin and Melanin-Concentrating Hormone
Article first published online: 23 JUL 2012
Copyright © 2012 by the Research Society on Alcoholism
Alcoholism: Clinical and Experimental Research
Volume 37, Issue 1, pages 123–131, January 2013
How to Cite
Chen, Y.-W., Barson, J. R., Chen, A., Hoebel, B. G. and Leibowitz, S. F. (2013), Glutamatergic Input to the Lateral Hypothalamus Stimulates Ethanol Intake: Role of Orexin and Melanin-Concentrating Hormone. Alcoholism: Clinical and Experimental Research, 37: 123–131. doi: 10.1111/j.1530-0277.2012.01854.x
- Issue published online: 4 JAN 2013
- Article first published online: 23 JUL 2012
- Manuscript Accepted: 5 APR 2012
- Manuscript Received: 14 DEC 2011
- USPHS Grant. Grant Number: AA12882
- E. H. Lane Foundation
- Lateral Hypothalamus;
- Melanin-Concentrating Hormone
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).
In Experiments 1 and 2, male Sprague-Dawley rats, after being trained to drink 9% EtOH , were microinjected in the LH with N-methyl-d-aspartate (NMDA) or its antagonist, D-AP5, 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).
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.
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.