Potentiation of yawning responses to the dopamine receptor agonists B-HT 920 and SND 919 by pindolol in the rat.
Subcutaneous injection of B-HT 920, a dopamine D2-receptor agonist, in doses ranging from 5 to 100 micrograms/kg, induced yawning behavior in rats. Yawning was also elicited by low doses (25-500 micrograms/kg sc) of SND 919, a newly synthesized dopamine receptor agonist. The yawning evoked by B-HT 920 or SND 919 was increased by the beta-adrenoceptor antagonist pindolol (20 mg/kg ip) which alone did not induce yawning. Stereotyped behavior did not appear after B-HT 920 or SND 919 given alone or in combination with pindolol. The results suggest that SND 919 as well as B-HT 920 has stimulatory activity at dopamine D2-receptors, and that pindolol may exert its enhancement of the yawning response to dopamine receptor agonists via blockade of beta-adrenoceptors.
Yamada
K
K
Department of Pharmacology, School of Medicine, Fukuoka University, Japan.
Matsumoto
S
S
Nagashima
M
M
Shirakawa
K
K
Furukawa
T
T
D000319:Adrenergic beta-Antagonists / Q000494:pharmacology*; D000818:Animals; D001381:Azepines / Q000494:pharmacology*; D052160:Benzothiazoles; D004305:Dose-Response Relationship, Drug; D008297:Male; D010869:Pindolol / Q000494:pharmacology*; D000077487:Pramipexole; D051381:Rats; D011919:Rats, Inbred Strains; D011954:Receptors, Dopamine / Q000187:drug effects / Q000502:physiology*; D017448:Receptors, Dopamine D2; D013844:Thiazoles / Q000494:pharmacology*; D015000:Yawning / Q000187:drug effects*
D000319:Adrenergic beta-Antagonists; D001381:Azepines; D052160:Benzothiazoles; D011954:Receptors, Dopamine; D017448:Receptors, Dopamine D2; D013844:Thiazoles; C024763:talipexole; D000077487:Pramipexole; D010869:Pindolol