Effect of Prolonged Food Reduction on the Rat Parotid Gland and Exocrine Pancreas

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Abstract
The purpose of this study is to determine the effect of a prolonged period of food reduction on the parotid gland and exocrine pancreas of the rat. Adult male rats were divided into experimental groups in which the daily food intake was reduced by 4 g (16%) and into control groups which were fed ad libitum. Animals were killed on days 4, 8, 12, 16, 24, 34, and 49. The parotid gland responds by a temporary hypertrophy which is characterized by an increase in gland weight, acinar cell hypertrophy (without changes in total DNA), and an elevated amylase content. These hypertrophic changes are progressive until day 12, when they start to decline. By day 24 they reach a stable plateau which remains somewhat higher, in all parameters, than the controls. Under the same conditions, the exocrine pancreas does not demonstrate any changes. The findings suggest that during the first period (days 1 to 12), the hypertrophy of the parotid gland is mainly due to reduced expulsion — hence, storage of secretory components in the acinar cells. The decline observed between days 12 and 24 may be due to reduced synthesis. The elevated values observed in the plateau period (days 24 to 49) can be accounted for by diurnal variation.