Environmental lighting and human salivary gland function.
Three experiments were conducted to (a) determine the effect of light deprivation on submandibular flow, (b) test for accommodation in darkness-induced parotid flow-rate depression, and (c) evaluate the effects of lights of widely varying intensities on parotid flow. Light deprivation decreased submandibular flow rate from 0.146 ml/min to 0.045 ml/min, a decrease of 69%. It is suggested that photic input through the retina provides stimulation to the salivary glands in the human through the superior cervical ganglion in a system similar to that present for the pineal. This implies that the sympathetic nervous system functions in the regulation of a component of the resting flow from both the parotid and submandibular glands. Series of parotid saliva samples collected in darkness did not reveal a pattern suggestive of accommodation to darkness. The effect of darkness on flow is as strong in the first sample as in those collected later under darkness. Reinstitution of light brings immediate restoration of the routine level of unstimulated salivary flow. A light intensity as low as 0.1 fc is sufficient to maintain the usual level of resting parotid flow. Increasing intensity up to 150 fc did not significantly increase this rate of flow.
D000065:Accommodation, Ocular; D003623:Dark Adaptation; D003624:Darkness; D004780:Environment, Controlled; D005725:Ganglia, Autonomic / Q000502:physiology; D006801:Humans; D008027:Light; D008029:Lighting; D008297:Male; D010306:Parotid Gland / Q000502:physiology; D012160:Retina; D012463:Saliva / Q000502:physiology; D012469:Salivary Glands / Q000502:physiology*; D013363:Submandibular Gland / Q000502:physiology; D013564:Sympathetic Nervous System / Q000502:physiology