Circadian rhythm of secretory and non-secretory proteins in parotid gland of rat
Vermouth, N.T.; Sanz, E.G.; Bellavia, S.L.
Acta Odontologica Latinoamericana Aol 2(1): 25-30
1985
ISSN/ISBN: 0326-4815 PMID: 3879825 Document Number: 253898
Content of alpha-amylase (.alpha.-1,4-glucan-4-glucanohydrolase, EC 3.2.1.1) and total soluble proteins of parotid glands from rats exposed to a photoperiod of 14 hr light (from 06.00 to 20.00 hours): 10 hr dark, were determined every two hours over 24 hr periods. The content of either secretory and non-secretory proteins in the gland was calculated from values of amylase and total soluble protein. Secretory proteins began to accumulate in the gland at 14.00 hr, rise steadily and reached a maximum at 22.00 hr and then fall. Soluble non-secretory proteins also exhibit a circadian rhythm whose profile is almost the "mirror image" of that observed for secretory proteins. Effect of fasting and constant light or darkness was studied. After 24 hr of fasting or after a 50 day-exposure to constant light or darkness, there was a significant increase in total soluble protein content and the diurnal variation in secretory and non-secretory proteins disappeared. Results indicate that secretory and non-secretory proteins are related and that the latter fraction may contain precursors of proteins secreted in saliva.