EFFECTS OF ADENOSINE RECEPTOR AGONISTS AND ANTAGONISTS ON PHYSOSTIGMINE-INDUCED YAWNING

The effect of adenosine receptor agonists and antagonists on physostig mine-induced yawning was investigated in intact or cannulated rats. In traperitoneal (i.p.) or intracerebroventricular (i.c.v.) administratio n of physostigmine to rats induced yawning dose dependently. I.p. or i .c.v. treatment of the animals with atropine, theophylline, 5-N-ethylc arboxamidoadenosine (NECA) or N-6-cyclohexyladenosine reduced the yawn ing induced by i.p. injection of physostigmine. I.p. administration of theophylline decreased the yawning induced by i.c.v injection of phys ostigmine. The inhibitory action of N 6-cyclohexyladenosine (i.p.) als o was decreased by s-phenyltheophylline (i.p.) pretreatment. It is con cluded that yawning induced by a central cholinergic mechanism and a c entral adenosine mechanism interacts with the cholinergic-induced beha viour.