[Adaptative differential maturation of neurohypophyseal provasotocin in amphibians: presence of hydrin 2(vasotocinyl-glycine) in anura but not in urodela].

Occurrence of hydrin 2 (vasotocinyl-glycine), an intermediate in the provasotocin processing, has been shown in the neurointermediate lobe of the pituitary of semi-aquatic or terrestrial amphibian species belonging to the order Anura, namely Rana esculenta, R. temporaria, R. pipiens (Ranidae), and Bufo bufo, B. marinus, B. ictericus (Bufonidae). In contrast hydrin 2 appears absent in species belonging to the order Urodela, namely the axolotl Ambystoma mexicanum (Ambystomidae) and the pleurodele newt, Pleurodela waltlii (Salamandridae). Whereas water transport through the skin and the urinary bladder is stimulated by vasotocin and hydrin 2 in anuran species, this stimulation is known not to occur in urodele species.