Immunohistochemical localization of the peptide sauvagine in the skins of phyllomedusine frogs

Abstract We have immunohistochemically localized immunoreactive sauvagine (ir-SV) in the skins of two species of frogs of the genus Phyllomedusa . Using rabbit antiserum against synthetic sauvagine conjugated to keyhole limpet hemocyanin, sauvagine-like immunoreactivity (SVLI) was detected in the lumina of all serous glands observed and in a few mucous glands in skin sections of adult P. sauvagei and P. trinitatus . SVLI was not detected in the skin of a third species, P. azurea . In P. trinitatus tadpoles, the presence of cutaneous SVLI was first observed at the onset of metamorphosis. Larval SVLI was evident in forming serous glands, but was not seen in mucous or lipid glands. Patchy SVLI was also observed in the dermis around the chromatophores in one tadpole. Preincubation of the antiserum with synthetic SV blocked SVLI; preincubation of the antiserum with urotensin I or rat or ovine corticotropin-releasing factor reduced but did not obliterate SVLI. The presence of SV in serous and mucous glands suggests that the release and function of SV may be different for each gland type, and the presence of SVLI in some mucous glands but not others suggests that biochemically discrete populations of mucous glands exist in the frog skin.