Functional significance of subtypes of 5-HT receptors in the rat spinal reflex pathway.
1. The functional significance of subtypes of 5-hydroxytryptamine (5-HT) receptors was studied in the rat spinal reflex pathway. 2. Ketanserin had no effect on the mono- (MSR) or polysynaptic reflex (PSR) in spinal rats, but decreased the PSR in intact rats. 3. 8-Hydroxy-2-(di-n-propylamino)tetralin (8-OH-DPAT) and 5-methoxy-N,N-dimethyltryptamine (5-MeODMT) decreased the MSR and increased the PSR in spinal rats. 4. Ketanserin antagonized the effects of 5-MeODMT without antagonizing the effects of 8-OH-DPAT. 5. Cinanserin had similar effects to those of ketanserin. 6. These results suggest that both 5-HT1A and 5-HT2 receptors mediate MSR inhibition and PSR augmentation in the spinal reflexes of spinal rats, and that the 5-HT2 receptor has a supraspinal tonic excitatory influence on the PSR in intact rats.
Nagano
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N
Department of Toxicology and Pharmacology, Faculty of Pharmaceutical Sciences, University of Tokyo, Japan.
Ono
H
H
Fukuda
H
H
D015115:5,6-Dihydroxytryptamine / Q000494:pharmacology; D017371:8-Hydroxy-2-(di-n-propylamino)tetralin; D000818:Animals; D002928:Cinanserin / Q000494:pharmacology; D006892:Hydroxydopamines / Q000494:pharmacology; D066298:In Vitro Techniques; D007275:Injections, Intravenous; D008297:Male; D016627:Oxidopamine; D051381:Rats; D011985:Receptors, Serotonin / Q000187:drug effects*; D012018:Reflex / Q000187:drug effects*; D012023:Reflex, Monosynaptic / Q000187:drug effects; D013116:Spinal Cord / Q000502:physiology*; D013764:Tetrahydronaphthalenes / Q000494:pharmacology; D013997:Time Factors
D006892:Hydroxydopamines; D011985:Receptors, Serotonin; D013764:Tetrahydronaphthalenes; D017371:8-Hydroxy-2-(di-n-propylamino)tetralin; D016627:Oxidopamine; D002928:Cinanserin; D015115:5,6-Dihydroxytryptamine