Existence of a gonadotropin-releasing hormone-like factor in the grass shrimp (black tiger prawn, Penaeus monodon)

The immunological and biological gonadotropin-releasing hormone (GnRH)-like activities in the acid extract of shrimp hepatopancreas (SHE) were studied. The immunological activity determined by a GnRH radioimmunoassay was 22.3 +/- 2.7 ng per ml of SHE. SHE increased luteinizing hormone (LH) release from rat anterior pituitary glands (APs) in vitro, and its biological activity was 42.9 +/- 28.5 ng per ml. No immunological activity was found in the acid extracts of eye ball, eye stalk, nerve and heart. These results suggest that the shrimp hepatopancreas has both immunological and biological GnRH-like activity.