Prolactin increases open-channel density of epithelial Na+channel in adult frog skin

Abstract

The short-term effect of prolactin on the skin of the adult tree frog Hyla arborea japonica was investigated using current-fluctuation analysis. Basolateral application of ovine prolactin (10·µg·ml -1 ) (1) increased the amilorideblockable short-circuit current (SCC) across the skin 2.6±0.4-fold and (2) increased the open-channel density (M) of the epithelial Na + channel 6.1±1.2-fold but decreased the single-channel current i to 0.4±0.1 times the control value (N=9). The increase in SCC induced by prolactin was thus due to an increase in M, not i. Apparently, in amphibians prolactin has not only a counteracting effect on metamorphosis but also a stimulatory effect on the development of adult-type features, such as this amiloride-blockable SCC.

Localization of prolactin receptor in the dorsal and ventral skin of the frog (Rana ridibunda)

“…It has been reported that Na + transport was stimulated (Takada & Kasai 2003), whereas basolateral K + current was inhibited (Takada 2005) in isolated ventral pelvic skin patch treated with PRL in a tree frog (Hyla arborea japonica Nikolskii, 1918). In adult bullfrog (Rana catesbeiana Shaw, 1802), PRL is involved in the regulation of Na + transport from the apical to the basolateral side across the skin (Takada & Hokari 2007).…”

Triphenyl phosphate-induced pericardial edema in zebrafish embryos is reversible following depuration in clean water

“…Prolactin is a freshwater-adapting hormone in zebrafish ( Breves et al, 2014 ) that regulates ions and water levels in vertebrates ( McCormick & Bradshaw, 2006 ). Interestingly, prolactin has varying functions in different vertebrates, ranging from (1) wound healing, seasonal hair growth, and milk production in mammals ( Foitzik et al, 2009 ); (2) increasing open-channel density of sodium channels in adult frog skin ( Takada & Kasai, 2003 ); and (3) altering skin permeability of osmoregulatory surfaces (gills, skin, kidney, intestine, bladder) in teleost fish ( Manzon, 2002 ). Prolactin regulates the amount of Na + , K + , and Cl − in embryonic zebrafish ( Shu et al, 2016 ).…”