The alpha-naphthoxyacetic acid-elicited retching involves dopaminergic inhibition in mice

Alpha-naphthoxyacetic acid (alpha-NOAA), one of the jumping-inducers, elicited a dose-dependent retching behavior at doses ranging from 250 to 550 mg/kg in mice and vomiting at a dose of 550 mg/kg in pigeons. Protoveratrine-A (PV-A, 0.1 mg/kg), a veratrum alkaloid, also induced retching in mice and vomiting in pigeons, while apomorphine (2 mg/kg) produced neither retching in mice nor vomiting in pigeons though it induced feeding in pigeons. The retching elicited by alpha-NOAA or PV-A was not significantly affected by scopolamine, aminooxyacetic acid and gamma-butyrolactone, but was markedly inhibited by apomorphine (2 mg/kg), this inhibitory effect being antagonized without significance by haloperidol which did not itself augment the retching. These results imply that the retching elicited by alpha-NOAA or PV-A seems to involve at least in part an inhibition of dopaminergic neuron activity.