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pubmed:abstractText |
We investigated the inhibitory effects of ??- or ??-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 ?(½)-AR agonist isoprenaline in rats. We also determined the inhibitory effect of metoclopramide, a dopamine D?-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 ?(½)-AR antagonist propranolol (5 mg/kg, s.c.) and ??-AR antagonist atenolol (2 mg/kg, s.c.) but not by the ??-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 ??-adrenoceptor activity and that salivary amylase activity is useful to detect emetogens with no direct ??-AR activation in rats, a species that does not exhibit vomiting.
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