Effect of X-radiation on Salivary Gland Growth in the Rat

Summary

Quantitative and histometric characteristics of sialadenotrophism induced in rats with isopropylnoradrenaline (ISOP) are described, with particular reference to rates of gland growth, rates of cell enlargement and cell proliferation in the submandibular (SM) salivary gland, and effects of ISOP on body-growth and heart weight. Glandular enlargement is principally due to hypertrophy (auxetic growth) and hyperplasia (replicative growth) of serous acinar salivary cells. Local irradiation of salivary tissues of rats before administration of ISOP caused a dose-dependent reduction of sialadenotrophism, 800 rads reducing gland growth by ∼ = 50 per cent. Histometric and autoradiographic studies showed that irradiation reduced growth by inhibiting cell replication, auxetic cell growth being radio-resistant. Cardiomegaly produced by ISOP in rats was also radioresistant. X-radiation inhibits adaptive growth of SM and parotid glands to a similar degree, but dose–effect curves differ, and the reasons for this are discussed. Radiation effects measured during the first 6 days' treatment of rats with ISOP are essentially independent of dosage and duration of treatment with ISOP. Induction of growth with ISOP is specific for salivary acinar cells and is a simple, convenient technique which may be used for radiobiological studies concerned with quantitative effects of radiation on the proliferative capacity of a highly differentiated, slowly-dividing tissue in vivo.