Thyroxine Reverses Deficits of Nerve Growth Factor and Epidermal Growth Factor in Submandibular Glands of Mice with Muscular Dystrophy*

Production of nerve growth factor (NGF) and epidermal growth factor (EGF) by granular tubule cells (GTC) in mouse submandibular glands is regulated by hormones. Mice afflicted with hereditary muscular dystrophy have reduced levels of salivary gland NGF and EGF, deficits which are associated with structural alterations in GTC. In this study, we questioned whether growth factor concentrations and GTC abnormalities in dystrophic mice can be altered by hormone treatment. RIA results indicate that T4 treatment of dystrophic mice, both male and female, elevates growth factor levels in submandibular glands to concentrations comparable to those in untreated normal littermates. Testosterone was ineffective in males, but stimulated significant production of NGF and EGF in females, although levels were 4- to 5-fold lower than in testosterone-treated nondystrophic females. Glands in dystrophic females treated with both T4 and testosterone contained NGF and EGF in amounts which were similar to those in normal females ...