title: Histological organization of the central nervous system and distribution of a gonadotropin-releasing hormone-like peptide in the blue crab, Portunus pelagicus.
abstract: We present a detailed histological description of the central nervous system (CNS: brain, subesophageal ganglion, thoracic ganglia, abdominal ganglia) of the blue crab, Portunus pelagicus. Because the presence of gonadotropin-releasing hormone (GnRH) in crustaceans has been disputed, we examine the presence and localization of a GnRH-like peptide in the CNS of the blue crab by using antibodies against lamprey GnRH (lGnRH)-III, octopus GnRH (octGnRH) and tunicate GnRH (tGnRH)-I. These antibodies showed no cross-reactivity with red-pigment-concentrating hormone, adipokinetic hormone, or corazonin. In the brain, strong lGnRH-III immunoreactivity (-ir) was detected in small (7-17 μm diameter) neurons of clusters 8, 9 and 10, in medium-sized (21-36 μm diameter) neurons of clusters 6, 7 and 11 and in the anterior and posterior median protocerebral neuropils, olfactory neuropil, median and lateral antenna I neuropils, tegumentary neuropil and antenna II neuropil. In the subesophageal ganglion, lGnRH-III-ir was detected in medium-sized neurons and in the subesophageal neuropil. In the thoracic and abdominal ganglia, lGnRH-III-ir was detected in medium-sized and small neurons and in the neuropils. OctGnRH-ir was observed in neurons of the same clusters with moderate staining, particularly in the deutocerebrum, whereas tGnRH-I-ir was only detected in medium-sized neurons of cluster 11 in the brain. Thus, anti-lGnRH-III shows greater immunoreactivity in the crab CNS than anti-octGnRH and anti-tGnRH-I. Moreover, our functional bioassay demonstrates that only lGnRH-III has significant stimulatory effects on ovarian growth and maturation. We therefore conclude that, although the true identity of the crab GnRH eludes us, crabs possess a putative GnRH hormone similar to lGnRH-III. The identification and characterization of this molecule is part of our ongoing research.
authors.affiliation: Department of Anatomy, Faculty of Science, Mahidol University, Rama 6 Road, Bangkok, 10400, Thailand.
authors.forename: Jirawat
authors.initials: J
authors.lastname: Saetan
authors.forename: Thanyaporn
authors.initials: T
authors.lastname: Senarai
authors.forename: Montakan
authors.initials: M
authors.lastname: Tamtin
authors.forename: Wattana
authors.initials: W
authors.lastname: Weerachatyanukul
authors.forename: Jittipan
authors.initials: J
authors.lastname: Chavadej
authors.forename: Peter J
authors.initials: PJ
authors.lastname: Hanna
authors.forename: Ishwar
authors.initials: I
authors.lastname: Parhar
authors.forename: Prasert
authors.initials: P
authors.lastname: Sobhon
authors.forename: Prapee
authors.initials: P
authors.lastname: Sretarugsa
mesh_terms: D000818:Animals; D057506:Arthropod Antennae / Q000166:cytology / Q000378:metabolism; D060829:Arthropod Proteins / Q000378:metabolism*; D003386:Brachyura / Q000166:cytology / Q000378:metabolism*; D002490:Central Nervous System / Q000166:cytology / Q000378:metabolism*; D007987:Gonadotropin-Releasing Hormone / Q000378:metabolism*; D009474:Neurons / Q000166:cytology / Q000378:metabolism; D019581:Neuropil / Q000166:cytology / Q000378:metabolism; D010455:Peptides / Q000378:metabolism*
chemical_list: D060829:Arthropod Proteins; D010455:Peptides; D007987:Gonadotropin-Releasing Hormone