PROTEIN-SYNTHESIS IN THE MAJOR SALIVARY-GLANDS OF THE RAT AND THE EFFECTS OF REFEEDING AND ACUTE ETHANOL INJECTION

Rates of protein synthesis in the major salivary glands of the rat wer e accurately determined in vivo using the 'flooding dose' technique an d the effects of reflex stimulation through feeding or acute ethanol t reatment were assessed. Rats were divided into three groups. The contr ol group was fasted overnight, the re-fed group was also fasted then r e-fed the following morning and the third group received an intraperit oneal injection of ethanol after an overnight fast. In control rats th e sublingual gland had a higher rate of protein synthesis than the oth er glands. After a feed the rate of protein synthesis in parotid gland s was approximately double that of controls whilst that of the submand ibular glands had increased by 24% and the sublingual glands remained unchanged. Acute ethanol injection led to a reduced rate of protein sy nthesis in all glands. The higher rate of protein synthesis in subling ual glands under fasting conditions may be related to the spontaneous secretion of fluid and protein from this gland, which would require a constant replenishment of secretory protein by synthesis. Protein synt hesis in the parotid gland, like secretion, appears to be closely link ed with the reflex stimulation caused by mastication. The smaller incr ease in rate of protein synthesis seen in the submandibular gland afte r a re-feed does not appear to have been recorded before. It could be mediated by the increased reflex stimuli caused by mastication or by s ome circulating factor. The mechanism by which ethanol reduces protein synthesis in all glands is uncertain.