Precocious differentiation of mouse parotid glands and pancreas induced by hormones

Changes of alpha-amylase activity (1,4-alpha-D-glucan glucanohydrolase, EC 3.2.1.1) in mouse parotid gland and pancreas were investigated during embryonic and postnatal development. Amylase activity in the parotid gland increased from around day 12 and reached the adult level on day 30. On the other hand, the activity in the pancreas increased during the last stage of gestation, decreased after birth, and then gradually increased from around day 15, reaching the adult level on day 35. Precocious differentiation of the parotid gland was induced by injections of hydrocortisone or thyroxine after birth, but these hormones did not have additive effects on the parotid gland. Injection of insulin had little effect when given alone, but suppressed the effects of the other two hormones on the gland. Only hydrocortisone increased the amylase activity in mouse pancreas during postnatal development, the other two hormones causing slight decrease in pancreatic amylase. Adrenalectomy and injection of hydrocortisone affected the parotid gland but not the pancreas of adult mice. These results suggest that hydrocortisone is involved in cytodifferentiations of the parotid gland and pancreas, and in maintenance of the parotid gland. Thyroxine may also be important in differentiation of the parotid gland.