title: Dopamine is differentially involved in the locomotor hyperactivity produced by manipulations of opioid, GABA and glutamate receptors in the median raphe nucleus.
abstract: The median raphe nucleus (MR) has been shown to exert a powerful influence on behavioral arousal and marked locomotor hyperactivity can be produced by intra-MR injections of a variety of drugs including GABAA and GABAB agonists, excitatory amino acid antagonists, and μ- and δ-opioid agonists. Other studies have indicated that the MR exerts an inhibitory influence on ascending dopamine systems, suggesting that MR induced alterations in activity may be mediated through changes in dopaminergic transmission. In the present study, we explored this possibility by examining whether systemic administration of the preferential D2 dopamine antagonist haloperidol is able to antagonize the hyperactivity produced by intra-MR injections of various drugs. We found that haloperidol completely blocked the locomotor response to intra-MR injections of the μ-opioid receptor agonist DAMGO and the δ-opioid receptor agonist DPDPE. In marked contrast, at doses which abolished the locomotor response to systemic amphetamine, haloperidol had no effect on the hyperactivity induced by intra-MR injections of GABAA agonist muscimol, the GABAB agonist baclofen, or the kainate/quisqualate antagonist pBB-PZDA, even though it suppressed baseline activity in these same animals. These results indicate that there must be at least two mechanisms capable of influencing behavioral arousal within the MR region, one of which is dependent on D2 dopamine receptors and the other is not.
authors: Department of Psychology, University of Illinois at Chicago M/C 285 1007 W. Harrison St., Chicago 60607-7137, IL, U.S.A; AMSRC, Department of Basic Science College of Oriental Medicine, Kyung Hee University, Seoul 130-701, Korea.
authors: Insop
authors: I
authors: Shim
authors: Department of Psychology, University of Illinois at Chicago M/C 285 1007 W. Harrison St., Chicago 60607-7137, IL, U.S.A.
authors: Thomas R
authors: TR
authors: Stratford
authors: Department of Psychology, University of Illinois at Chicago M/C 285 1007 W. Harrison St., Chicago 60607-7137, IL, U.S.A. Electronic address: davew@uic.edu.
authors: David
authors: D
authors: Wirtshafter
mesh_terms: D015102:3,4-Dihydroxyphenylacetic Acid / Q000378:metabolism; D000661:Amphetamine / Q000494:pharmacology; D000701:Analgesics, Opioid / Q000494:pharmacology; D000704:Analysis of Variance; D000818:Animals; D004298:Dopamine / Q000378:metabolism*; D004305:Dose-Response Relationship, Drug; D018683:Excitatory Amino Acid Agents / Q000494:pharmacology; D018682:GABA Agents / Q000494:pharmacology; D006719:Homovanillic Acid / Q000378:metabolism; D008297:Male; D009043:Motor Activity / Q000187:drug effects*; D011903:Raphe Nuclei / Q000187:drug effects / Q000502:physiology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D018079:Receptors, GABA / Q000378:metabolism*; D017470:Receptors, Glutamate / Q000378:metabolism*; D011957:Receptors, Opioid / Q000378:metabolism*
chemical_list: D000701:Analgesics, Opioid; D018683:Excitatory Amino Acid Agents; D018682:GABA Agents; D018079:Receptors, GABA; D017470:Receptors, Glutamate; D011957:Receptors, Opioid; D015102:3,4-Dihydroxyphenylacetic Acid; D000661:Amphetamine; D004298:Dopamine; D006719:Homovanillic Acid
keywords: Dopaminergic; Hyperlocomotion; Locomotion; Nucleus centralis superior; RMTg; Tegmentum