The effects of hypophysectomy upon the endogenous levels of cyclic AMP during forelimb regeneration of adult newts (Notophthalmus viridescens).

Cyclic AMP is believed to play a role in limb regeneration. Using high pressure liquid chromatography, endogenous levels of cyclic AMP in regenerating tissues of normal and of hypophysectomized adult newts were estimated. In normally regenerating limbs, cyclic AMP levels were depressed 7 days after amputation and were elevated at 14 and 21 days. In contrast, limb tissues of hypophysectomized newts displayed elevated cyclic AMP levels at 7, 14 and 21 days after amputation. A correlation exists between depressed levels of cyclic AMP and the occurrence of dedifferentiation and elevated levels of cyclic AMP and morphogenesis. Although elevated cyclic AMP levels later in regeneration might influence morphogenesis, depressed levels of cyclic AMP alone appear inadequate to account for dedifferentiation.