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Interactions of drugs acting on central dopamine receptors and cholinoceptors on yawning responses in the rat induced by apomorphine, bromocriptine or physostigmine
Author(s) -
Zarrindast M.R.,
Poursoltan M.
Publication year - 1989
Publication title -
british journal of pharmacology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.432
H-Index - 211
eISSN - 1476-5381
pISSN - 0007-1188
DOI - 10.1111/j.1476-5381.1989.tb11893.x
Subject(s) - apomorphine , bromocriptine , physostigmine , sch 23390 , sulpiride , agonist , endocrinology , atropine , medicine , dopamine receptor , chemistry , dopamine agonist , stimulation , pharmacology , cholinergic , dopamine , prolactin , receptor , hormone , dopaminergic
1 Yawning was induced by subcutaneous (s.c.) injection of low doses of apomorphine to rats. This effect decreased with increasing doses of the drug. 2 Intraperitoneal (i.p.) pretreatment of animals with sulpiride (D 2 ‐receptor blocker) reduced the frequency of the yawns induced by apomorphine, while SCH 23390 (D 1 ‐receptor blocker, s.c.) pretreatment increased the small number of yawns which was induced by higher doses of apomorphine. Administration of SCH 23390 alone to rats also produced a low degree of yawning. 3 Apomorphine‐induced yawning was decreased in animals treated with SK&F 38393 (D 1 ‐agonist, i.p.), atropine (i.p.) or theophylline (i.p.). 4 Intraperitoneal injection of bromocriptine (D 2 ‐agonist) in rats also induced dose‐dependent yawning. The effect was decreased in animals pretreated with sulpiride, while SCH 23390 pretreatment did not change bromocriptine‐induced yawning significantly. Pretreatment of animals with SK&F 38393, atropine or theophylline reduced the number of yawns induced by bromocriptine. 5 Physostigmine (i.p.) but not neostigmine (i.p.) also induced yawning. The effect was antagonized by atropine or theophylline but not by sulpiride. Administration of SK&F 38393 decreased yawning induced by physostigmine. This inhibitory influence of SK&F 38393 was reduced by SCH 23390 in pretreated animals. Treatment of animals with SCH 23390 or bromocriptine increased the frequency of yawns induced by physostigmine. 6 It is concluded that D 2 ‐receptor activation elicits yawning through influence on cholinergic mechanisms, whereas D 1 ‐receptor stimulation decreases yawning behaviour by a negative influence on the cholinergic system.