Prolactin induces increase in the specific gravity of salamander, Hynobius retardatus, that raises adaptability to water.
The migration of the salamander, Hynobius retardatus, from land to water, which normally occurs in the breeding season, was induced by the injection of prolactin. The migration was accompanied by certain morphological changes (wider tail or swollen body); the observed morphological changes resembled those of salamanders collected from ponds during the breeding season. The prolactin-treated salamanders sank to the bottom of the water. In contrast, the control salamanders that did not receive prolactin floated near the water surface. The specific gravity of the whole body of the prolactin-treated animals was greater than unity. Prolactin injection induced a remarkable enlargement of the tissue between the skin and muscle, in which a considerable amount of mucopolysaccharide-rich substance accumulated. Because of the hydrophilic nature of the mucopolysaccharides, and increased mucopolysaccharide may absorb more water, which, in turn, may result in an increase of the osmotic pressure of the serum. This may eventually cause the animals to migrate from land to water to quench the "thirst." The absorption of water may make the specific gravity greater, and this allows the animals to sink in water.
D000064:Acclimatization / Q000187:drug effects*; D000818:Animals; D001835:Body Weight / Q000187:drug effects; D011388:Prolactin / Q000494:pharmacology*; D013550:Swimming; D014562:Caudata / Q000502:physiology*; D014867:Water
D014867:Water; D011388:Prolactin