Theophylline stimulation of binding of radioiodinated rat prolactin to murine mammary gland.

Characteristics of prolactin receptors of murine mammary glands were studied. Mammary gland exhibited low but specific binding to 125I-rPRL (rat prolactin). Receptors were heat susceptible and partly protein in nature. Theophylline--both in vitro and in vivo treatment--enhanced the binding of 125I-rPRL to receptors. It remains to be established whether this action of theophylline is mediated through cyclic AMP "Sparing" effect or through its direct effect on cell membrane stabilization.