Mitosis Induced in Adult Rat Parotid Following Normal Activity of the Gland 1

Abstract

Summary

When normal function is restored by introduction of a solid food regimen to animals previously maintained on liquid diet (Metrecal) mitotic activity is induced, reaches a maximum after 2 days, (22 ± 2 per 1000 acinar cells), and remains evident until 7 days. The mitotic burst is partially inhibited in the presence of either atropine or Inderal. A decrease in DNA at 2 days followed by restoration to normal levels at 7 days suggests that, during the course of transition from low to normal functional status of the gland, cell loss must occur but is compensated for by the concurrently occurring cell proliferation. Normal physiological activity thus can act as the stimulus for inducing mitosis in the adult parotid where growth potential is low as well as in the immature parotid where growth potential is high. Glands of fasted rats exhibit similar mitotic bursts following refeeding with solid food, but not when they are refed using liquid food. A role of masticatory activity in this response is thus implied.