Gonadotropin-releasing hormone (GnRH) binding characteristics in the testis of goldfish (Carassius auratus)

✍ Scribed by Pati, Debananda ;Habibi, Hamid R.

• Publisher: John Wiley and Sons
• Year: 1993
• Tongue: English
• Weight: 965 KB
• Volume: 267
• Category: Article
• ISSN: 0022-104X
• DOI: 10.1002/jez.1402670208

✦ Synopsis

Abstract

Gonadotropin‐releasing hormone (GnRH) binding sites were characterized in the goldfish testis using an analog of salmon GnRH ([D‐Arg^6^, Trp^7^, Leu^8^, Pro^9^‐NEt]‐GnRH; sGnRH‐A) as a labeled ligand. Binding of sGnRH‐A to goldfish testicular membrane homogenate was found to be saturable, reversible, and dependent on time, temperature, and tissue concentration. Addition of unlabeled sGnRH‐A displaced the bound ^125^ I‐sGnRH‐A in a dose‐related manner. Hill plot as well as Scatchard analysis indicated the presence of two classes of binding sites, a high affinity/low capacity site and a low affinity/high capacity site in the goldfish testis. Bound ^125^I‐sGnRH‐A was also found to be displaceable by sGnRH ([Trp^7^, Leu^8^]‐GnRH) and cGnRH‐II ([His^5^, Trp^7^, Tyr^8^,]‐GnRH) which occur naturally in the goldfish brain. sGnRH‐A and cGnRH‐II were found to bind with greater affinity than sGnRH to the goldfish testicular GnRH binding sites. The findings provide the first characterization of testicular GnRH binding sites in a teleost species. © 1993 Wiley‐Liss, Inc.