The autonomic nervous system regulates the secretion of bioactive proteins and peptides from salivary glands that can be important in systemic physiological responses. The prohormone submandibular rat-1, which is highly expressed in rat submandibular glands, can be cleaved to produce polypeptides with analgesic and anti-inflammatory activities. Human genes related to submandibular rat-1 have conserved biological functions and are potentially important in pain suppression, erectile function, and inflammation. In this study we describe the differential expression and posttranslational modification of submandibular rat-1 protein in salivary glands, the urogenital tract, lung, blood, and saliva in male Sprague-Dawley and Brown Norway rats. Submandibular rat-1 protein is secreted into saliva after the administration of beta-adrenergic or cholinergic agonists. Removal of the sympathetic ganglion that innervates the salivary glands results in increased levels of submandibular rat-1 protein in salivary glands. The secretion of submandibular rat-1 in response to physiological stress may provide a large pool of submandibular rat-1-derived peptide products that can promote analgesia and decrease inflammation locally and systemically. This pathway may be conserved among mammals and may constitute an important anti-inflammatory and analgesic response to stress.

Chronic and acute stress have profound effects on inflammation. In rats, allergic inflammation is regulated by the sympathetic nervous system acting on salivary glands. Human asthma is frequently accompanied by salivary gland inflammation. Salivary gland dysfunction in stressed individuals could enhance asthma severity. Salivary gland prohormone SMR1 (submandibular rat-1) is cleaved into two peptides that are anti-inflammatory in rats, mice, dogs, sheep, cats, and human cells in pulmonary inflammation, food allergy, septic shock, pancreatitis, and spinal cord injury. We hypothesized that modulation of the autonomic nervous system would change the expression, processing, and secretion of SMR1 and its peptides. Rats were injected with saline, isoproterenol, or pilocarpine, or the superior cervical ganglion was excised. Saliva, blood, and tissues were collected and analyzed for SMR1. Adrenergic stimulation caused the majority of SMR1 into be secreted into saliva in 60 min. Removal of the superior cervical ganglion that innervates the salivary glands changed SMR1 protein levels in the salivary glands. SMR1 secretion into saliva in response to acute stress may provide a large pool of SMR1-derived peptide products that mediate anti-inflammatory responses locally and systemically. This research is funded by AllerGen NCE.