title: Possible involvement of differing classes of dopamine D-2 receptors in yawning and stereotypy in rats.
abstract: The present experiments were performed to investigate differences in the properties of the dopamine D-2 receptors related to yawning and stereotypy. Subcutaneous injection of talipexole (B-HT 920) (10-250 micrograms/kg) or SND 919 ((S)-2-amino-4,5,6,7-tetrahydro-6-propylamino-benzothiazole) (25-500 micrograms/kg) evoked yawning behavior with bell-shaped responses. However, SK&F 38393 (1-phenyl-2,3,4,5-tetrahydro-(1H)-3-benzazepine-7,8-diol) (0.5-10 mg/kg SC) did not elicit yawning and decreased yawning responses to low doses of talipexole (25 micrograms/kg SC) or SND 919 (100 micrograms/kg SC). These low but effective doses for inducing yawning of talipexole or SND 919 in combination with SK&F 38393 (0.5-10 mg/kg SC) did not elicit stereotypy. In contrast, yawning behavior was not produced after very high doses of talipexole (500 micrograms/kg SC) or SND 919 (1000 micrograms/kg SC) given alone or in combination with SK&F 38393 (0.5-10 mg/kg SC). These extremely high doses of talipexole or SND 919 evoked slight stereotypy, which was enhanced by the combined treatment with SK&F 38393. The present results suggest that the dopamine D-2 receptors related to yawning are more sensitive to dopamine receptor agonists than those related to stereotypy, and that concurrent stimulation of postsynaptic dopamine D-1 receptors with D-2 receptors reduces the incidence of yawning but enhances that of stereotypy.
authors.affiliation: Department of Pharmacology, School of Medicine, Fukuoka University, Japan.
authors.forename: K
authors.initials: K
authors.lastname: Yamada
authors.forename: M
authors.initials: M
authors.lastname: Nagashima
authors.forename: H
authors.initials: H
authors.lastname: Kimura
authors.forename: S
authors.initials: S
authors.lastname: Matsumoto
authors.forename: T
authors.initials: T
authors.lastname: Furukawa
mesh_terms: D015647:2,3,4,5-Tetrahydro-7,8-dihydroxy-1-phenyl-1H-3-benzazepine / Q000494:pharmacology; D000818:Animals; D001381:Azepines / Q000494:pharmacology; D052160:Benzothiazoles; D015259:Dopamine Agents / Q000494:pharmacology*; D008297:Male; D000077487:Pramipexole; D051381:Rats; D011919:Rats, Inbred Strains; D011954:Receptors, Dopamine / Q000187:drug effects / Q000502:physiology*; D017448:Receptors, Dopamine D2; D013239:Stereotyped Behavior / Q000187:drug effects*; D013844:Thiazoles / Q000494:pharmacology; D015000:Yawning / Q000187:drug effects*
chemical_list: D001381:Azepines; D052160:Benzothiazoles; D015259:Dopamine Agents; D011954:Receptors, Dopamine; D017448:Receptors, Dopamine D2; D013844:Thiazoles; D015647:2,3,4,5-Tetrahydro-7,8-dihydroxy-1-phenyl-1H-3-benzazepine; C024763:talipexole; D000077487:Pramipexole