title: Effect of gonadotropin-releasing hormone on phagocytic leucocytes of rainbow trout.
abstract: To clarify the role of gonadotropin-releasing hormone (GnRH) in the fish immune system, in vitro effect of GnRH was examined in phagocytic leucocytes of rainbow trout (Oncorhynchus mykiss). Gene expression of GnRH-receptor was detected by RT-PCR in leucocytes from head kidney. Administration of sGnRH increased proliferation and mRNA levels of a proinflammatory cytokine, tumor necrosis factor (TNF)-α, in trout leucocytes. Superoxide production in zymosan-stimulated phagocytic leucocytes was also increased by sGnRH in a dose-related manner from 0.01 to 100 nM. There was no significant effect of sGnRH on mRNA levels of growth hormone (GH) expressed in trout phagocytic leucocytes. Immunoneutralization of GH by addition of anti-salmon GH serum into the medium could not block the stimulatory effect of sGnRH on superoxide production. These results indicate that GnRH stimulates phagocytosis in fish leucocytes through a GnRH-receptor-dependent pathway, and that the effect of GnRH is not mediated through paracrine GH in leucocytes.
authors.affiliation: Freshwater Fisheries Research Division, National Research Institute of Aquaculture, Nikko, Tochigi 321-1661, Japan. yadat@fra.affrc.go.jp
authors.forename: Takashi
authors.initials: T
authors.lastname: Yada
mesh_terms: D000818:Animals; D049109:Cell Proliferation / Q000187:drug effects; D002478:Cells, Cultured; D004305:Dose-Response Relationship, Drug; D015870:Gene Expression / Q000187:drug effects*; D007987:Gonadotropin-Releasing Hormone / Q000494:pharmacology*; D013006:Growth Hormone / Q000235:genetics / Q000378:metabolism; D053583:Interleukin-1beta / Q000235:genetics / Q000378:metabolism; D007962:Leukocytes / Q000378:metabolism*; D017686:Oncorhynchus mykiss / Q000235:genetics* / Q000378:metabolism; D010586:Phagocytes / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D011966:Receptors, LHRH / Q000235:genetics*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015398:Signal Transduction / Q000187:drug effects / Q000235:genetics; D013481:Superoxides / Q000378:metabolism; D014409:Tumor Necrosis Factor-alpha / Q000235:genetics / Q000378:metabolism
chemical_list: D053583:Interleukin-1beta; D012333:RNA, Messenger; D011966:Receptors, LHRH; D014409:Tumor Necrosis Factor-alpha; D013481:Superoxides; D007987:Gonadotropin-Releasing Hormone; D013006:Growth Hormone