The Journal of Neuroscience, September 24, 2008, 28(39):9840-9849; doi:10.1523/JNEUROSCI.1713-08.2008
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Behavioral/Systems/Cognitive
Involvement of the Limbic Basal Ganglia in Ethanol Withdrawal Convulsivity in Mice Is Influenced by a Chromosome 4 Locus
Gang Chen,1,3
Laura B. Kozell,1,2,3
Robert Hitzemann,1,3,4 and
Kari J. Buck1,3,4
Departments of 1Behavioral Neuroscience and 2Psychiatry, Oregon Health & Science University, 3Portland Alcohol Research Center, and 4Portland Veterans Affairs Medical Center, Portland, Oregon 97239
Correspondence should be addressed to Dr. Gang Chen, Veterans Affairs Medical Center, Research Service (R&D40), 3710 SW US Veterans Hospital Road, Portland, OR 97239. Email: chenga{at}ohsu.edu
Physiological dependence and associated withdrawal episodes are thought to constitute a motivational force that sustains ethanol (alcohol) use/abuse and may contribute to relapse in alcoholics. Although no animal model duplicates alcoholism, models for specific factors, like the withdrawal syndrome, are useful for identifying potential genetic and neural determinants of liability in humans. We generated congenic mice that confirm a quantitative trait locus (QTL) on chromosome 4 with a large effect on predisposition to alcohol withdrawal. Using c-Fos expression as a high-resolution marker of neuronal activation, congenic mice demonstrated significantly less neuronal activity associated with ethanol withdrawal than background strain mice in the substantia nigra pars reticulata (SNr), subthalamic nucleus (STN), rostromedial lateral globus pallidus, and ventral pallidum. Notably, neuronal activation in subregions of the basal ganglia associated with limbic function was more intense than in subregions associated with sensorimotor function. Bilateral lesions of caudolateral SNr attenuated withdrawal severity after acute and repeated ethanol exposures, whereas rostrolateral SNr and STN lesions did not reduce ethanol withdrawal severity. Caudolateral SNr lesions did not affect pentylenetetrazol-enhanced convulsions. Our results suggest that this QTL impacts ethanol withdrawal via basal ganglia circuitry associated with limbic function and that the caudolateral SNr plays a critical role. These are the first analyses to elucidate circuitry by which a confirmed addiction-relevant QTL influences behavior. This mouse QTL is syntenic with human chromosome 9p. Given the growing body of evidence that a gene(s) on chromosome 9p influences alcoholism, our results can facilitate human research on alcohol dependence and withdrawal.
Key words: seizure; c-Fos; substantia nigra; lesion; Mpdz; MUPP1
Received Dec. 31, 2007;
revised July 22, 2008;
accepted Aug. 24, 2008.
Correspondence should be addressed to Dr. Gang Chen, Veterans Affairs Medical Center, Research Service (R&D40), 3710 SW US Veterans Hospital Road, Portland, OR 97239. Email: chenga{at}ohsu.edu