PRESENCE OF SAUVAGINE-LIKE EPITOPES IN THE INTERRENAL GLAND OF THE BULLFROG RANA-CATESBEIANA

Immunocytochemistry was used to investigate the presence of corticotro pin-releasing factor-like peptides in the interrenal (adrenal) glands of the bullfrog Rana catesbeiana by using specific antisera raised aga inst synthetic nonconjugated rat/human corticotropin-releasing factor, urotensin I, and sauvagine. From these three antisera, covering a bro ad range of corticotropin-releasing factor-like immunoreactivities, on ly the sauvagine antiserum gave positive immunoreactivity. Sauvagine i mmunoreactivity was found in cortical cells grouped into cords in the renal zone of the interrenal gland. The central and subcapsular cords were less stained. Tyrosine hydroxylase-positive chromaffin cells were not sauvagine-immunoreactive. The immunoreactivity was abolished, in all cases, by previous immuno-absorption of the sauvagine antiserum wi th synthetic sauvagine (0.1 mu M), but it was not eliminated by sucker (Catostomus commersoni) urotensin I, sole (Hippoglos-soides elassodon ) urotensin I, sucker corticotropin-releasing factor, rat/human cortic otropin-releasing factor, or ovine corticotropin-releasing factor (0.1 -10 mu M). In a sauvagine radioimmunoassay, interrenal extracts displa ced I-125-sauvagine from antiserum only partially, and not in parallel with the sauvagine standard curve. The results suggest that the sauva gine immunoreactivity in the R. catesbeiana interrenal gland may repre sent a novel sauvagine-like peptide.