Secretion of epidermal growth factor in parotid saliva in diabetic patients: role of autonomic innervation.

Parotid saliva was collected over a 12-min period from 24 insulin dependent diabetic patients with varying degrees of autonomic neuropathy and 12 age and sex matched non-diabetic controls. Epidermal growth factor (EGF) concentrations in saliva were measured by radio-immunoassay. The EGF concentrations in diabetics with no autonomic neuropathy or with combined autonomic neuropathy were equivalent but secretion of EGF was significantly elevated at the 6- and 12-min periods of collection in diabetic patients with early or established autonomic neuropathy. It is postulated that when parasympathetic autonomic neuropathy is present a relative "over-activity" of the sympathetic innervation promotes release of salivary EGF. This sympathetic predominance may maintain salivary EGF concentration despite the elevated salivary flow and volume which is associated with parasympathetic autonomic neuropathy.