Possible involvement of β1 receptors in various emetogen-induced increases in salivary amylase activity in rats

We investigated the inhibitory effects of β1- or β2-adrenoceptor (ar) antagonists on salivary amylase secretion produced by various emetic agents,such as cisplatin,apomorphine,and lithium chloride (licl),or the non-emetic agent β1/2-ar agonist isoprenaline in rats. we also determined the inhibitory effect of metoclopramide,a dopamine d2-receptor antagonist,on increases in the salivary amylase activity induced by apomorphine or granisetron,a 5-ht 3-receptor antagonist,on licl-induced increased salivary amylase activity. isoprenaline (0.01 mg/kg,s.c.) produced an increase in salivary amylase and the increase was inhibited by the β1/2-ar antagonist propranolol (5 mg/kg,s.c.) and β1-ar antagonist atenolol (2 mg/kg,s.c.) but not by the β2-ar antagonist butoxamine (8 mg/kg,s.c.). the increased amylase activity induced by cisplatin (15 mg/kg,i.v.),apomorphine (3 mg/kg,s.c.),or licl (120 mg/kg,i.p.) was inhibited significantly by atenolol (2 mg/kg,s.c.) but not by butoxamine (8 mg/kg,s.c.). in addition,increases in amylase activities induced by apomorphine and licl were inhibited significantly by metoclopramide (10 mg/kg,i.v.) and granisetron (3 mg/kg,i.v.),respectively. these results suggest that salivary amylase secretion induced by various emetogens is involved in β1- adrenoceptor activity and that salivary amylase activity is useful to detect emetogens with no direct β1-ar activation in rats,a species that does not exhibit vomiting. © the japanese pharmacological society.