Avidin induction by theophylline in vivo and in vitro

Avidin induction in chick tissues in vivo and in vitro was studied by a phosphodiesterase inhibitor, theophylline, and compared to progesterone-dependent induction. Theophylline (100 mg/kg, ip) caused a significant increase in avidin content only in the oviduct of diethylstilbestrol-treated chicks, but not in the lung, muscle, intestine, plasma, or in the bursa of Fabricius. Diethylstilbestrol priming was necessary for oviductal avidin induction in vivo by theophylline. In the oviduct culture, theophylline at a concentration between 100 and 500 micrograms/ml caused a dose-dependent increase in avidin production. Effects of theophylline and progesterone on avidin synthesis in oviduct culture were synergistic. Avidin production was dependent on protein and RNA synthesis, since induction was inhibited by cycloheximide and actinomycin D. Avidin induction by theophylline resembled progesterone-dependent induction, beginning 9 h after the injection in vivo and 12 h after administration of these drugs in vitro. Avidin induced by theophylline showed heat-induced biotin exchange identical to that of progesterone-induced avidin, indicating close similarity of these proteins. The results suggest that theophylline can mimic the action of progesterone on avidin production, and that cyclic nucleotides may have a role in the regulation of avidin synthesis.