Effects of pretreatment with androgen or thyroid hormone on androgen-induced proliferation of granular convoluted tubular cells in mouse submandibular glands.

The effects of pretreatment with androgen or thyroid hormone on androgen-induced proliferation of granular convoluted tubular cells (GCT cells) in the submandibular glands of ovariectomized female BALB/c or C57BL/6 mice were investigated. The proliferation of GCT cells was estimated by their labeling index. Daily injections of 5 alpha-dihydrotestosterone (DHT) (100 micrograms/mouse/day) caused a transient increase in the labeling index of GCT cells of ovariectomized 60-day-old BALB/c mice during the first four injections, but injections of thyroxine (T4) (15 micrograms/mouse/day) did not. On the other hand, both DHT and T4 increased the esteroprotease activity, a marker of the differentiation of GCT cells, time dependently. Injections of DHT into ovariectomized 102-day-old BALB/c mice also caused a transient increase in the labeling index of GCT cells. However, pretreatment of ovariectomized 60-day-old BALB/c mice with DHT for 4 or 14 days completely abolished the DHT-induced increase in the labeling index of 102-day-old mice, and pretreatment with T4 for 14 days reduced this increase. Pretreatment with DHT or T4 for 14 days did not affect the DHT-induced increase in esteroprotease activity. Pretreatment of ovariectomized 60-day-old C57BL/6 mice with DHT for 14 days also completely abolished the DHT-induced increase in the labeling index of GCT cells at the age of 102 days, but pretreatment with T4 for 14 days did not affect the increase.(ABSTRACT TRUNCATED AT 250 WORDS)