Sensitivity and specificity of salamandrid integumental transepithelial potential to prolactin

Abstract

The effects of ovine prolactin (oPRL), bovine growth hormone (bGH) and human placental lactogen (hPL) on in vivo integumental transepithelial potential (TEP) were examined in two salamandrid urodeles, adult terrestrial-phase Taricha granulosa and the juvenile red-eft stage of Notophthalmus viridescens. TEP in efts treated with 1.0 microgram oPRL/2 days fell from 73.3 +/- 6.1 to 15.2 +/- 5.5 mV by Day 7 (P less than 0.001), whereas the TEP of efts treated with either 1.0 or 10 micrograms bGH/2 days remained at control levels for as long as 24 days. TEP in efts treated with a single dose of 10 micrograms oPRL dropped from 65.74 +/- 4.1 to 23.0 +/- 3.4 mV (P less than 0.01) in 3 days. Efts treated with various doses of oPRL showed a linear log total dose response over the range of 0.05 to 10.0 micrograms oPRL/animal, with a minimum detectable total dose of 0.4 micrograms/g (0.01 IU/g). In the same experiments, tail height increased by Day 7 in efts treated every other day with 10.0 micrograms oPRL, but not 1.0 microgram oPRL or either 1.0 or 10.0 micrograms bGH/2 days. In Oregon newts injected every other day with 10 micrograms oPRL, TEP decreased by 33% in 8 days (P less than 0.05), whereas in animals treated with 10 micrograms bGH/2 days, TEP did not change from control values even after 23 days. TEP in Oregon newts receiving a single dose of 100 micrograms oPRL dropped to 68% of initial values within 2 days (P less than 0.05), but subsequently recovered to control values 3 weeks after the last injection.(ABSTRACT TRUNCATED AT 250 WORDS)