title: Effects of hydrostatic pressure on monoaminergic activity in the brain of a tropical wrasse, Halicoeres trimaculatus: possible implication for controlling tidal-related reproductive activity.
abstract: Most wrasse species in tropical waters exhibit daily spawning synchrony with a preference for high tide. Fish perceive tidal rhythm cues through sensory organs and activate the brain-pituitary-gonadal endocrine axis for synchronous gonadal maturation, although how the tidal-related spawning cycle is controlled endogenously is not known. The purpose of this study was to examine whether hydrostatic pressure has an impact on brain monoamine levels and reproductive activities in the threespot wrasse Halichoeres trimaculatus. The contents of dopamine (DA), 3,4-dihydroxyphenylacetic acid (DOPAC), serotonin (5-HT), and 5-hydroxyindoleacetic acid (5-HIAA) in the brain were measured using high-performance liquid chromatography and an electrochemical detection system. Exposing the fish to hydrostatic pressure occurring at a 3-m depth (~30 kPa) resulted in an increase in 5-HIAA/5-HT over 3h and a decrease in DOPAC/DA over 6h. No changes in gonadosomatic index or oocyte diameter were observed between the groups when female fish were reared at 0-m and 3-m depth for 3h. Hydrostatic pressure did not alter pituitary mRNA abundance of follicle stimulating hormone-β or luteinizing hormone-β. However, in vitro culture of ovaries from pressurized fish in the presence of human chorionic gonadotropin resulted in an increase in 17α,20β-dihydroxy-4-pregnen-3-one in the medium. These results suggest that hydrostatic pressure activates oocyte maturation through brain monoaminergic activity in this tropical wrasse species.
authors: Department of Chemistry, Biology and Marine Science, Faculty of Science, University of the Ryukyus, Nishihara, Okinawa 903-0213, Japan. takemura@sci.u-ryukyu.ac.jp
authors: Akihiro
authors: A
authors: Takemura
authors: Yoriko
authors: Y
authors: Shibata
authors: Yuki
authors: Y
authors: Takeuchi
authors: Sung-Pyo
authors: SP
authors: Hur
authors: Nozomi
authors: N
authors: Sugama
authors: Md
authors: M
authors: Badruzzaman
mesh_terms: D006907:17-alpha-Hydroxypregnenolone / Q000378:metabolism; D015102:3,4-Dihydroxyphenylacetic Acid / Q000378:metabolism*; D000818:Animals; D001921:Brain / Q000378:metabolism*; D006063:Chorionic Gonadotropin / Q000494:pharmacology; D004298:Dopamine / Q000378:metabolism*; D005260:Female; D005640:Follicle Stimulating Hormone / Q000378:metabolism; D006801:Humans; D006874:Hydrostatic Pressure; D006897:Hydroxyindoleacetic Acid / Q000378:metabolism*; D007986:Luteinizing Hormone / Q000378:metabolism; D009924:Organ Culture Techniques; D010053:Ovary / Q000187:drug effects / Q000378:metabolism; D010473:Perciformes / Q000502:physiology*; D010902:Pituitary Gland / Q000378:metabolism; D012098:Reproduction / Q000502:physiology*; D012701:Serotonin / Q000378:metabolism*; D055871:Tidal Waves
chemical_list: D006063:Chorionic Gonadotropin; D015102:3,4-Dihydroxyphenylacetic Acid; D012701:Serotonin; D006907:17-alpha-Hydroxypregnenolone; D006897:Hydroxyindoleacetic Acid; D007986:Luteinizing Hormone; D005640:Follicle Stimulating Hormone; D004298:Dopamine