hydrin-2 and Dehydration

1. The neurohypophysial osmoregulatory hormones of the African toad Bufo regularis, a species adapted to estivate under dry and hot conditions, have been investigated. Vasotocin and hydrin 2 (vasotocinyl-Gly) have been identified by their retention times in high-pressure reverse-phase liquid chromatography and coelution with synthetic peptides, their pharmacological properties (vasotocin) and microsequencing. 2. Vasotocin-associated neurophysin (MSEL-neurophysin type) has been characterized by its N-terminal amino acid sequence. 3. In toads subjected to dehydration by evaporation (20% weight loss) or to osmotic stress by immersion in 2% NaCl for 3 hr (6% weight loss), the molar ratio hydrin 2/vasotocin (about 2:1) remained similar to the one observed in control animals. 4. In toads exposed to saline solution, there was a large decrease (roughly 30%) in the amounts of both hormones in the neuro-hypophysis. Environmental conditions for distinct secretions of vasotocin and hydrin 2 remain to be found.

Topics: Amino Acid Sequence; Animals; Arginine Vasopressin; Biological Assay; Bufonidae; Chromatography, High Pressure Liquid; Dehydration; Environment; Female; In Vitro Techniques; Molecular Sequence Data; Neurophysins; Osmolar Concentration; Oxytocin; Pituitary Gland, Posterior; Pregnancy; Protein Precursors; Rats; Spectrophotometry, Ultraviolet; Vasotocin