Inhibition of the antimetamorphic action of prolactin in larval Ambystoma tigrinum by lysine vasopressin, arginine vasotocin, and aldosterone.

Abstract

Abstract In an earlier study it was reported that oxytocin was able to block the antimetamorphic action of prolactin (PRL) in larval tiger salamanders, Ambystoma tigrinum ( Platt and LiCause, 1980 ). In this study, we have examined the effects of lysine vasopressin (LVP), arginine vasotocin (AVT), and aldosterone on induced metamorphosis in larval A. tigrinum and on the inhibition of this process by PRL. Both LVP and AVT were found to interfere with the inhibition of gill resorption, tail fin regression, and body weight loss by PRL. An anti-PRL effect of aldosterone was observed but appeared to be limited to the gill. AVT alone had a significant acceleratory effect on body weight loss during metamorphosis. A “water balance” response was observed in only one case. Twenty-four hours after treatment with LVP and PRL, this group of animals did show a significant increase in body weight. These results are discussed with regard to the problem posed by neurohypophysial hormone contamination of PRL preparations and in context with our hypothesis that the antimetamorphic action of PRL is at least partially osmoregulatory in nature.