Adrenergic Signal Transduction in Aging Parotid and Submandibular Salivary Glands

This study assessed agonist- and post-receptor-stimulated adenylate cyclase (AC) activity in parotid and submandib-ular salivary glands from female F-344 rats of 3,12, and 24 months of age. Isoproterenol-stimulated dose-response activation of adenylate cyclase was unchanged between 3 and 12 months but decreased at 24 months (p <.05). Forskolin-stimulated AC activity, representing catalytic unit activity, was decreased at 24 months in the parotid (p <.05) and at 12 months (p <.05) and 24 months (p <.01) in the submandibular gland, ^-adrenergic signal transduction in salivary glands stimulates the secretion of salivary proteins that have important functions in the maintenance of oral health. SALIVARY secretion is mediated by the autonomic ner-vous system, which regulates the water, ionic, and pro-tein composition of the saliva (Marmary et al., 1989). In particular, the fS-adrenergic signal transduction pathway is primarily responsible for the control of the salivary protein secretions (Marmary et al., 1989). (3-adrenergic function has been reported to decrease with age in various organ systems (Scarpace et al., 1991). Both the parotid and submandibular glands of rats (Roth and Adelman, 1973) and humans (An-drew, 1952) undergo morphological changes with age. fi-adrenergic receptors (BAR) have been reported to be un-changed with age in parotid glands from male Wistar rats (Ito et al., 1981) and decreased with age in the submandibular glands from mice (Fattoretti et al., 1982). Despite the abun-dance of literature on the normal biochemical and physiologi-cal aspects of BAR in the major salivary glands, there is little information on post-receptor signal transduction in aging rats. In the present study we investigated adenylate cyclase activity in the parotid and submandibular salivary glands of 3-, 12-