The effects of the chemical sympathectomy with reserpine on salivary flow rates and protein secretion by rat submandibular glands in response to various agonists.

Abstract

This study was designed to determine whether the submandibular glands of rats subjected to chemical sympathectomy with reserpine administration showed abnormalities in five types of receptor functions, and to determine whether tyramine acted as a false neurotransmitter.The wet tissue weights of the submandibular glands of rats significantly increased one and two days after chemical sympathectomy with reserpine. Supersensitivities of fluid and protein secretion in response to isoproterenol, noradrenaline, clonidine and physalaemin were clearly seen in the reserpine-treated animals when compared with those of controls. In particular, supersensitivity to noradrenaline occurred in fluid and protein secretion in the reserpine-treated animals. The β-type proteins secreted in controls in response to noradrenaline at a low dose (1 mg/kg) were completely replaced by the α-type proteins in reserpine-treated animals. Tyramine was a completely false neurotransmitter. This study suggests that almost complete release of noradrenaline from the sympathetic nerve terminals could occur in the submandibular glands of rats treated with reserpine according to this protocol, and that released noradrenaline could potentiate the α-type protein secretion by the granular duct cells of the submandibular glands of rats.