THE OCCURRENCE AND DISTRIBUTION OF GNRH IN THE BRAIN OF ATLANTIC HAGFISH, AN AGNATHA, DETERMINED BY CHROMATOGRAPHY AND IMMUNOCYTOCHEMISTRY

In Atlantic hagfish (Myxine glutinosa), chromatographic and immunocyto chemical evidence showed that the brain contains a gonadotropin-releas ing hormone (GnRH)-like molecule that is closely related to lamprey Gn RH-III. The chromatographic studies (HPLC) used specific antisera dire cted against mammalian GnRH and lamprey GnRH-I. In addition to these a ntisera, other specific antisera were tested in immunocytochemical stu dies, including chicken GnRH-I, chicken-GnRH-II, salmon GnRH, and lamp rey GnRH-III. Using a lamprey GnRH-I antiserum, an early eluting GnRH form coeluted on HPLC with lamprey GnRH-III standard and an unknown fo rm coeluted with the chicken GnRH-II standard. Radioimmunoassay of bra in tissue detected GnRH immunoreactivity only when the lamprey GnRH-I antibody was used. A GnRH-like immunoreactivity was also obtained immu nocytochemically in the neurohypophysis with the use of antisera again st chicken GnRH-II, salmon GnRH, lamprey GnRH-I, and lamprey GnRH-III. These studies indicate that, contrary to earlier reports, hagfish do have a GnRH-like molecule that is more closely related, in terms of im munological determinants, to lamprey GnRH-III than to other currently known vertebrate GnRH molecules. (C) 1995 Academic Press, Inc.