Modulation of oral movements by intranigral 5-hydroxytryptamine receptor agonists in the rat.
Bilateral infusion of 5-hydroxytryptamine (5-HT) agonists into the substantia nigra pars reticulata (SNr) of awake rats was shown to influence oral behavior. The 5-HT1A agonist (R)-8-hydroxy-2-(di-propylamino)- tetralin (8-OH-DPAT) (1.3-13 nmol on each side) produced a dose-dependent depression of vacuous chewing movements (VCMs) that lasted about 20 min. The (R)-8-OH-DPAT-induced depression of VCMs was blocked by the simultaneous intranigral infusion of a specific 5-HT1A antagonist [(-)-(S)-5-fluoro-8-hydroxy-2-(dipropylamino)tetralin HCl (UH-301)], which had no effect when given alone. Another 5-HT1A agonist [(5-methoxy-N,N-dimethyltryptamine hydrogen oxalate (5-MeO-DMT)] also reduced VCM frequencies. Intranigral infusion of the nonspecific 5-HT-agonists 1-(3-triflouro-methylphenyl) piperazine (TFMPP) and 1(m-chlorophenyl)-piperazine (mCPP) and a 5-HT3 agonist [2-methyl-5-hydroxytryptamine (2-Me-5-HT)] increased VCM after 5- to 10-nmol doses. Another 5-HT3 agonist (1-phenylbiguanide) and a 5-HT2 agonist [1-(4-bromophenyl-2,5-dimethoxy)-2-aminopropane (DOB)] had no significant effect. As most 5-HT receptors in the SNr are of the 5-HT1B subtype, these results suggest that the increased VCM frequency was mediated via nigral 5-HT1B receptors. The importance of 5-HTergic mechanisms in the development of drug-induced dyskinesias is discussed.
Liminga
U
U
Department of Psychiatry at Ulleråker, Uppsala University, Sweden.
Johnson
A E
AE
Andrén
P E
PE
Gunne
L M
LM
D017371:8-Hydroxy-2-(di-n-propylamino)tetralin / Q000037:antagonists & inhibitors / Q000494:pharmacology; D000818:Animals; D004305:Dose-Response Relationship, Drug; D005260:Female; D007267:Injections; D009055:Mouth / Q000187:drug effects; D051381:Rats; D017207:Rats, Sprague-Dawley; D012044:Regression Analysis; D012702:Serotonin Antagonists; D017366:Serotonin Receptor Agonists / Q000008:administration & dosage / Q000494:pharmacology*; D013239:Stereotyped Behavior / Q000187:drug effects*; D013378:Substantia Nigra / Q000033:anatomy & histology / Q000502:physiology*
D012702:Serotonin Antagonists; D017366:Serotonin Receptor Agonists; D017371:8-Hydroxy-2-(di-n-propylamino)tetralin