Treatment with dexamethasone alters yawning behavior induced by cholinergic but not dopaminergic agonist

Because stressful manipulations have been reported to modify drug-induced y awning, the present study investigated the effects of single and repeated t reatment with a synthetic glucocorticoid, dexamethasone (DEXA) on apomorphi ne- and pilocarpine-induced yawning in male rats. Neither single nor repeat ed treatment with DEXA altered apomorphine-induced yawning. Single administ ration of DEXA, however, resulted in an increased number of yawns induced b y pilocarpine. Conversely, repeated administration of DEXA led to a decreas ed number of yawns induced by pilocarpine. In conclusion, the present findi ngs show that dopaminergic and cholinergic are distinctly altered by DEXA, in terms of yawning behavior when animals received DEXA. (C) 1999 Elsevier Science, Inc.