Role of dorsal and median raphe nuclei in lower lip retraction in rats.
Induction of lower lip retraction after local infusion of the selective 5-HT1A receptor agonist (+/-)-8-hydroxy-2-(di-n-propylamino)tetralin (8-OH-DPAT) in the dorsal and median raphe nuclei was measured. Infusion of 8-OH-DPAT (2.5, 5 and 10 micrograms/rat) into the median raphe nucleus caused an immediate and dose-dependent lower lip retraction. After infusion into the dorsal raphe nucleus a higher dose was needed. The lowest dose of 8-OH-DPAT that induced lower lip retraction was 10 micrograms/rat. Infusion of 8-OH-DPAT (10 micrograms/rat) into the pontine reticular nucleus induced the same degree of lower lip retraction as seen after infusion of the compound into the dorsal raphe nucleus. 8-OH-DPAT-induced lower lip retraction was attenuated by s.c. injection of the preferential 5-HT2C receptor agonist m-chlorophenyl-piperazine. The results suggest that lower lip retraction is mediated by 5-HT1A receptors in the median rather than in the dorsal raphe nucleus.
Department of Neuropharmacology, N.V. Organon, Oss, Netherlands.
H H
HH
Berendsen
F G
FG
Bourgondien
C L
CL
Broekkamp
D017371:8-Hydroxy-2-(di-n-propylamino)tetralin / Q000008:administration & dosage / Q000633:toxicity*; D000818:Animals; D001522:Behavior, Animal / Q000187:drug effects; D004305:Dose-Response Relationship, Drug; D007279:Injections, Subcutaneous; D008046:Lip / Q000187:drug effects* / Q000502:physiology; D008297:Male; D009043:Motor Activity / Q000187:drug effects; D010879:Piperazines / Q000494:pharmacology; D011903:Raphe Nuclei / Q000187:drug effects / Q000378:metabolism / Q000502:physiology*; D051381:Rats; D017208:Rats, Wistar; D011985:Receptors, Serotonin / Q000187:drug effects / Q000502:physiology*; D044263:Receptors, Serotonin, 5-HT1; D017366:Serotonin Receptor Agonists / Q000494:pharmacology
D010879:Piperazines; D011985:Receptors, Serotonin; D044263:Receptors, Serotonin, 5-HT1; D017366:Serotonin Receptor Agonists; D017371:8-Hydroxy-2-(di-n-propylamino)tetralin; C015068:1-(3-chlorophenyl)piperazine