Immunohistochemical detection of GnRH-like peptides in the neural ganglia and testis of Haliotis asinina

Abstract

Gonadotropin releasing hormone (GnRH) is a peptide that is conserved in both vertebrate and invertebrate species. In this study, we have demonstrated the distribution pattern of two isoforms of GnRH-like peptides in the neural ganglia and testis of reproductively mature male abalone, H. asinina, by immunohistochemistry and whole mount immunofluorescence. We found octopus (oct) GnRH and tunicate-I (t) GnRH-I immunoreactivities (ir) in type 1 neurosecretory cells (NS1) and they were expressed mostly within the ventral horn of the cerebral ganglion, whereas in pleuropedal ganglia they were localized primarily in the dorsal horn. Furthermore, tGnRH-I-ir were strongly detected in fibers at the caudal part of the cerebral ganglia and both ventral and dorsal horns of the pleuropedal ganglia. In the testis, only octGnRH-ir was found primarily in the granulated cell and central capillaries within the trabeculae. These results suggest that multiple GnRH-like peptides are present in the neural ganglia which could be the principal source of their production, whereas GnRH may also be synthesized locally in the testis and act as the paracrine control of testicular maturation.

Characterization of an abalone gonadotropin-releasing hormone and its effect on ovarian cell proliferation

“…A wide distribution of GnRH-immunoreactivity was observed throughout the cerebral and pleuropedal ganglia, specifically within cells that have been characterized as NS1. This is in agreement with previous studies that have reported the presence of a GnRH-like peptide in the ganglia of both male and female H. asinina (Nuurai et al, 2014). In that study, the antibody used was from octopus GnRH and tunicate I GnRH, whereas this study used an antibody generated against H. asinina GnRH.…”

“…However, using the non-abalone GnRH-specific antibody, we have found GnRH-immunoreactivity in the testis (Nuurai et al, 2014). We propose that the neural ganglia are the principal source of GnRH production, while GnRH synthesized locally in the testis may act as the paracrine control of gamete maturation.…”

Identification and Characterization of Neuropeptides by Transcriptome and Proteome Analyses in a Bivalve Mollusc Patinopecten yessoensis

“…GnRH is a neurohormone central to the regulation of reproductive functions in vertebrates. In molluscs, GnRH has been identified in O. vulgaris ( Iwakoshi et al, 2002 ; Iwakoshi-Ukena et al, 2004 ), A. californica ( Zhang et al, 2008 ; Jung et al, 2014 ), L. gigantea ( Veenstra, 2010 ), P. fucata ( Stewart et al, 2014 ), C. gigas ( Stewart et al, 2014 ), and H. asinine ( Nuurai et al, 2014 ). Herein, a P. yessoensis gene encoding GnRH precursor was identified.…”