Nature and distribution of gonadotropin-releasing hormone (GnRH) in the brain, and GnRH and GnRH binding activity in serum of the spotted dogfish Scyliorhinus canicula.
The distribution of different molecular forms of gonadotropin-releasing hormone (GnRH) in the brain and serum of the spotted dogfish, Scyliorhinus canicula, was investigated by an indirect immunofluorescence method, using antisera against salmon (s-), chicken-II (cII-) and mammalian (m-) GnRHs, and by reverse-phase high-performance liquid chromatography (RP-HPLC) coupled with radioimmunoassays. Five GnRH molecular forms were demonstrated on the basis of the retention time in the RP-HPLC system. The characteristics of four of these GnRH peptides are consistent with those of m-, cII-, dogfish (df-), and sGnRH. The fifth form appears to be novel. Immunoreactive sGnRH structures were confined to the diencephalon; whereas cIIGnRH and mGnRH were found in the telencephalon and diencephalon. cIIGnRH- and dfGnRH-like molecules were detected in the serum. Moreover, a specific, low-affinity GnRH binding protein (GnRH-BP) was found in the serum of the spotted dogfish. The binding of [125I]sGnRHA to the serum GnRH-BP was dependent on incubation time, equilibrium being reached within 1 hr at 4 degrees; binding was rapid and completely reversible. Scatchard analysis yielded a linear plot with a Kd of 7.9 x 10(-7) M. The presence of a GnRH-BP in spotted dogfish serum suggests a probable action of GnRH via the general circulation.
D'Antonio
M
M
Department of Zoology, University of Alberta, Edmonton, Canada.
Vallarino
M
M
Lovejoy
D A
DA
Vandesande
F
F
King
J A
JA
Pierantoni
R
R
Peter
R E
RE
D000818:Animals; D001921:Brain / Q000378:metabolism*; D001923:Brain Chemistry; D002851:Chromatography, High Pressure Liquid; D004027:Diencephalon / Q000378:metabolism; D004284:Dogfish / Q000097:blood / Q000378:metabolism*; D005260:Female; D005455:Fluorescent Antibody Technique; D007987:Gonadotropin-Releasing Hormone / Q000032:analysis / Q000097:blood / Q000378:metabolism*; D008297:Male; D013687:Telencephalon / Q000378:metabolism; D014018:Tissue Distribution
D007987:Gonadotropin-Releasing Hormone