The Effect of Adrenergic Agonists and Antagonists on the Expression of Proteins in Rat Submandibular and Parotid Glands

Abstract

The present investigation was undertaken to study the effect of adrenoreceptor modulators on the expression of salivary proteins. Sprague-Dawley rats were treated for 10 consecutive days with adrenergic agonists isoproterenol, dobutamine, terbutaline, salbutamol, methoxyphenamine, or methoxamine. Antiserum to selected salivary proteins was used to compare the concentration of these proteins in the submandibular and parotid glands of treated animals. Chronic treatments of rats (50 μmol/ kg body weight for 10 d) with either isoproterenol or dobutamine induced synthesis of a cysteine-proteinase inhibitor (cystatin) in the submandibular glands. When isoproterenol was injected concomitantly with the mixed β-antagonist propranolol or the β1-adrenergic antagonists metaprolol, proctocol, or atenolol, the induction of cystatin was totally suppressed. However, the β2-antagonist, ICI-118551, produced only partial reduction in cystatin induction elicited by isoproterenol. On the contrary, rats treated with either isoproterenol or P,-agonists demonstrated a significantly reduced concentration of serine-proteinase kallikrein in submandibular glands. The decrease observed in submandibular kallikrein of rats treated with isoproterenol was prevented by concomitant treatment with β 1,-antagonists but not with β2-antagonists. Because kallikreins are produced by ductal cells and cystatins are produced by acinar cells of submandibular glands, these observations suggest that there may be differential control of expression of proteins synthesized by ductal and acinar cells. Chronic treatment of rats with nonselective P-agonist isoproterenol or β 1,-selective agonists increased markedly the proline-rich proteins (PRP) in parotid glands, but the parotid amylase concentration was not significantly affected by β-adrenergic agonists. Coinjection of β1-antagonists along with isoproterenol blocked the induction of PRP in the parotid glands. These findings suggest that there may be a differential control of expression of proteins by different cell populations of salivary glands.