Effects of a Chemical Carcinogen on the Submaxillary Gland of Albino Rats Treated with Isoproterenol1

Ninety 3-month-old male and female albino rats were divided into 6 equal groups. Three groups of animals received daily i.p. injections (20 mg) of isoproterenol for a 2-week period. Pellets of powdered 9,10-dimethyl-l ,2-benzanthracene (DMBA) were implanted into the right submaxillary salivary glands of the ex perimental animals 2 weeks prior to, simultaneous with, and 2 weeks after commencement of isoproterenol injections. The re maining groups of animals served as controls. The isoproterenol control animals revealed submaxillary gland changes consisting of hypertrophy and hyperplasia of acinar cells and a decrease in the number of ducts. The submaxillary glands of the DMBA-implanted control animals underwent a series of alterations with the formation of well-advanced epidermoid carcinomas at the termination of the experiment. Ani mals treated with isoproterenol and implanted with DMBA showed a delay in the sequence of alterations and a decrease in the number and size of malignant neoplasms. It is suggested that the salivary gland neoplasms do not arise from acinar tissue, but rather from the ductal elements or from ductlike tissue.