ラット顎下腺の分泌機能に及ぼす3種類のフェノールアミンの作用

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Only two in vitro studies have been reported on the effects of phenolamines, namely tyramine, octopamine and norphenylephrine (Npp), on the secretory function of the rat submandibular glands (SMG). The present study was designed, thus, to determine the effects of three phenolamines, injected i.v. and i.p. at various doses, on the secretory function of the SMG with and without various types of autonomic blockers and also to determine their effects on the levels of both cyclic nucleotides and three catecholamines, namely dopamine, noradrenaline and adrenaline, in the SMG. The findings obtained mainly by the Lowry's method, amino acid analysis, isoelectric focusing electrophoresis (IEF), spectrophotometry and radioimmunoassay were as follows : 1. The three phenolamines injected i.v. and i.p. were potent sialogogues at relatively high doses. 2. Salivation in response to the phenolamines injected i.v. and i.p. by the SMG was significantly reduced with all of the autonomic antagonists and also completely abolished in combination with prazosin (1mg/kg) and propranolol (10mg/kg). 3. The volumes of saliva secreted, salivary flow rates, the amounts of protein secreted and protease activities were dose-dependently increased, whereas no dose-dependent change was observed for the concentration of protein of submandibular saliva in response to the phenolamines injected i.v. and i.p. 4. Most of the above parameters in both i.v. and i.p. experiments were significantly reduced by the phenolamines in combination with most of the autonomic blockers. The α-adrenoceptor antagonists had stronger reducing activity than β-adrenoceptor antagonists. The protein concentration was significantly increased by the phenolamines in combination with α-adrenoceptor blockers, whereas with β-adrenoceptor blockers it was significantly reduced. 5. Pargyline affected the secretory function of the SMG more strongly than disulfiram in response to both tyramine and octopamine. 6. The α-type proteins were secreted by the SMG after i.v. and i.p. injections in all doses of the phenolamines except the minimum doses of the phenolamines injected i.p. which caused the secretion of the β-type proteins by tyramine and octopamine. The secretion of the α-type proteins was not affected by the phenolamines with any types of β-adrenoceptor antagonists, atropine or two enzyme inhibitors for monoamine-oxidase and dopamine-β-hydroxylase. However, all the α-adrenoceptor antagonists except yohimbine at various doses completely converted the α-type proteins into the β-type. 7. Amino acid composition was, in general, characteristic of the α-type of proteins secreted by the SMG. 8. The levels of cAMP were significantly reduced by the phenolamines, whereas with Npp, but not with tyramine and octopamine, the level of cGMP was significantly increased in the SMG. 9. The level of noradrenaline, but not of adrenaline and dopamine, was significantly increased with Npp, but not with tyramine and octopamine.
福岡歯科大学学会の論文
1992-06-30

ラット顎下腺の分泌機能に及ぼす3種類のフェノールアミンの作用

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