030121.500 030818.166 031518.852 091313.875 091420.495 130504.333 140518.836 190121.500 202518.250 211815.666 030120*750 180114*100 180120*006 080916*750 Presence of sauvagine-like epitopes in the interrenal gland of the bullfrog Rana catesbeiana G.C. Gonzalez 1 , S. Bountzioukas 2, * , K. Lederis 2 , K. Lukowiak 1 1 Neuroscience Research Group, Faculty of Medicine, The University of Calgary, 3330 Hospital Drive N.W., Calgary, Alberta, Canada T2N 4N1 2 Department of Pharmacology, Faculty of Medicine, The University of Calgary, 3330 Hospital Drive N.W., Calgary, Alberta, Canada T2N 4N1 &misc:Received: 30 March 1995 / Accepted: 17 July 1995 &p.1:Abstract. Immunocytochemistry was used to investigate the presence of corticotropin-releasing factor-like pep- tides in the interrenal (adrenal) glands of the bullfrog Rana catesbeiana by using specific antisera raised against synthetic nonconjugated rat/human corticotro- pin-releasing factor, urotensin I, and sauvagine. From these three antisera, covering a broad range of cortico- tropin-releasing factor-like immunoreactivities, only the sauvagine antiserum gave positive immunoreactivity. Sauvagine immunoreactivity 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 immunoreac- tivity was abolished, in all cases, by previous immuno- absorption of the sauvagine antiserum with synthetic sauvagine (0.1 μM), but it was not eliminated by sucker (Catostomus commersoni) urotensin I, sole (Hippoglos- soides elassodon) urotensin I, sucker corticotropin-re- leasing factor, rat/human corticotropin-releasing factor, or ovine corticotropin-releasing factor (0.1–10 μM). In a sauvagine radioimmunoassay, interrenal extracts dis- placed 125 I-sauvagine from antiserum only partially, and not in parallel with the sauvagine standard curve. The re- sults suggest that the sauvagine immunoreactivity in the R. catesbeiana interrenal gland may represent a novel sauvagine-like peptide. &kwd:Key words: Sauvagine – Corticotropin-releasing factor – Immunocytochemistry – Interrenal gland – Rana ca- tesbeiana (Anura) Introduction Peptides of the so-called corticotropin-releasing factor (CRF) superfamily of neuropeptides appear to be well represented in the central nervous systems of all verte- brates. CRF-like substances have been reported in a num- ber of species, including a primitive vertebrate, the stur- geon Acipenser ruthenus (Gonzalez et al. 1992a), modern fishes (Fellman et al. 1984; Olivereau et al. 1984, 1988; Yulis et al. 1986), amphibians (Gonzalez and Lederis 1988; Gonzalez et al. 1995b), birds (Józsa et al. 1984; Ball et al. 1989), and mammals (Kawata et al. 1982; Sko- fitsch and Jacobowitz 1985; Sakanaka et al. 1987). Se- quence comparisons of the CRFs found in the vertebrate central nervous system indicate that two fish CRFs from the white sucker Catostomus commersoni (Morley et al. 1991), two amphibian CRFs from Xenopus laevis (Sten- zel-Poore et al. 1992), and the mammalian CRFs are al- most identical. Other homologous neuropeptides with up to 50% identity to known CRFs are urotensin I (UI), first isolated from C. commersoni (Lederis et al. 1982), and sauvagine (SVG), first isolated from the skin of the frog Phyllomedusa sauvagei (Montecucchi et al. 1979). Both UI and SVG have corticotropin-releasing activity when applied in vitro to dispersed pituitary cells and in vivo to conscious or CRF-suppressed rats (Brown et al. 1982; Negri et al. 1983; Rivier et al. 1983). Recent evidence indicates that UI-like immunoreac- tivity is present in the Aplysia californica central ner- vous system, where it colocalizes with urotensin II- and angiotensinogen-like immunoreactivities (Gonzalez et al. 1991, 1992b, 1995a). This suggests that a UI-like molecule could be an invertebrate evolutionary precursor of the CRFs found in the vertebrate central nervous system. Alignments of vertebrate CRF-like peptides and insect diuretic peptides from Periplaneta americana, Lo- custa migratoria, Acheta domesticus, and Manduca sexta (Kay et al. 1992) indicate that the latter peptides may also be considered homologous to the CRF family. Besides the localization and activity of CRF in the central nervous system, a CRF was also known to occur Funding provided by a grant from the Medical Research Council of Canada (MRC) to K. L.S. B was an MRC visiting scientist. * Present address: Department of Physiology, University of Thes- saloniki, Thessaloniki, Greece Correspondence to: G.C. Gonzalez&/fn-block: Cell Tissue Res (1996) 283:117–123 © Springer-Verlag 1996