Effects of dopamine receptor antagonists on gastrin and vomiting responses to apomorphine.
Apomorphine (0.05 mg/kg intravenously) was given to conscious dogs, and gastrin levels were measured in peripheral venous blood with a radioimmunoassay. Apomorphine induced an increase of gastrin levels which peaked at 5 min. The peripheral dopamine D-2/DA2 receptor antagonist domperidone (0.2 mg/kg), but not halopemide (0.1-1 mg/kg) nor the D-1/DA1 receptor antagonist SCH 23,390 (0.1 mg/kg), blocked the gastrin response to apomorphine. Both domperidone and halopemide, but not SCH 23,390, blocked the apomorphine-induced vomiting. These results suggest that apomorphine increases gastrin levels by an action at D-2/DA2 receptors, which are situated outside the blood brain barrier and differ from the receptor inducing the vomiting.
D000818:Animals; D014150:Antipsychotic Agents / Q000494:pharmacology; D001058:Apomorphine / Q000494:pharmacology*; D001552:Benzazepines / Q000494:pharmacology; D004285:Dogs; D004294:Domperidone / Q000031:analogs & derivatives / Q000494:pharmacology; D005260:Female; D005755:Gastrins / Q000378:metabolism*; D008297:Male; D011954:Receptors, Dopamine / Q000187:drug effects*; D014149:Tranquilizing Agents; D014839:Vomiting / Q000139:chemically induced*
D014150:Antipsychotic Agents; D001552:Benzazepines; D005755:Gastrins; D011954:Receptors, Dopamine; D014149:Tranquilizing Agents; D004294:Domperidone; C017357:halopemide; D001058:Apomorphine