Concentration of gonadotropin-releasing hormone in the brain during metamorphosis in the lamprey,Petromyzon marinus

✍ Scribed by Youson, John H. ;Sower, Stacia A.

• Publisher: John Wiley and Sons
• Year: 1991
• Tongue: English
• Weight: 574 KB
• Volume: 259
• Category: Article
• ISSN: 0022-104X
• DOI: 10.1002/jez.1402590316

✦ Synopsis

Abstract

The concentration of lamprey gonadotropin‐releasing hormone (lamprey GnRH) and relative amounts of a second GnRH‐like form from brains of larvae (ammocoetes) and individuals during the seven stages of lamprey metamorphosis were measured using a lamprey GnRH radioimmunoassay following elution on a reverse‐phase high performance liquid chromatography (HPLC) system. Lamprey GnRH was not detectable in ammocoetes and was present in small quantities in only a few samples of metamorphosing individuals in stages 1–5 (0.475–0.667 ng/brain) but was more conspicuous at stage 6 (0.873 ± 0.308) and had increased significantly (7.8 ± 0.371) by the final stage (7). The second, GnRH‐like hormone eluted at a different time on HPLC compared to lamprey GnRH and was detected by the lamprey GnRH antiserum. This second GnRH‐like hormone appeared at stage 4 and was present, at a progressively increased relative concentration, in almost all samples to the end of metamorphosis where the level of 5.15 ± 0.625 ng/brain was significantly lower than that of lamprey GnRH. The brain weight increased by the final two stages but concentration of the two hormones/brain sample weight revealed, for both hormones, a trend of increased levels as metamorphosis progressed and significant differences in concentration between stages 6 and 7. The timing of increased concentration of GnRH in the brain of metamorphosing lampreys is discussed with reference to the acceleration of gonad maturation during and immediately after metamorphosis.