Dopaminergic-cholinergic interaction involved in yawning behavior in rat

A behaviorl study was performed in an attmpt to understand the dopaminergic-cholinergic neuronal mechanisms involved in yawning responses induced by bromocriptine (BRC), a selective dopamine D-2 receptor agonist. BRC (1-10mg/kg, i.p.) evoked yawning responses, which were pronounced at 2.5mg/kg and characterized by the head moving downward. BRC-induced yawning responses were potentiated by a low dose of apomorphine (0.1mg/kg, i.p.) and reserpine (2mg/kg, i.p.) but were inhibited by high dose of apomorphine, low and high doses of haloperidol (0.02 and 1mg/kg, i.p.), sulpiride (20mg/kg, i.p.), α -methyl-p-tyrosine (α -MPT