title: Occurrence and neuroendocrine role of D-aspartic acid and N-methyl-D-aspartic acid in Ciona intestinalis.
abstract: Probes for the occurrence of endogenous D-aspartic acid (D-Asp) and N-methyl-D-aspartic acid (NMDA) in the neural complex and gonads of a protochordate, the ascidian Ciona intestinalis, have confirmed the presence of these two excitatory amino acids and their involvement in hormonal activity. A hormonal pathway similar to that which occurs in vertebrates has been discovered. In the cerebral ganglion D-Asp is synthesized from L-Asp by an aspartate racemase. Then, D-Asp is transferred through the blood stream into the neural gland where it gives rise to NMDA by means of an NMDA synthase. NMDA, in turn, passes from the neuronal gland into the gonads where it induces the synthesis and release of a gonadotropin-releasing hormone (GnRH). The GnRH in turn modulates the release and synthesis of testosterone and progesterone in the gonads, which are implicated in reproduction.
authors.affiliation: Laboratory of Neurobiology, Stazione Zoologica 'A. Dohrn', Villa Comunale, 80121 Naples, Italy. daniello@szn.it
authors.forename: Antimo
authors.initials: A
authors.lastname: D'Aniello
authors.forename: Patrizia
authors.initials: P
authors.lastname: Spinelli
authors.forename: Antonietta
authors.initials: A
authors.lastname: De Simone
authors.forename: Salvatore
authors.initials: S
authors.lastname: D'Aniello
authors.forename: Margherita
authors.initials: M
authors.lastname: Branno
authors.forename: Francesco
authors.initials: F
authors.lastname: Aniello
authors.forename: George H
authors.initials: GH
authors.lastname: Fisher
authors.forename: Maria M
authors.initials: MM
authors.lastname: Di Fiore
authors.forename: Rakesh K
authors.initials: RK
authors.lastname: Rastogi
mesh_terms: D000818:Animals; D001224:Aspartic Acid / Q000737:chemistry / Q000502:physiology*; D002938:Ciona intestinalis / Q000378:metabolism* / Q000502:physiology; D005260:Female; D007987:Gonadotropin-Releasing Hormone / Q000502:physiology; D006066:Gonads / Q000378:metabolism; D066298:In Vitro Techniques; D007447:Invertebrate Hormones / Q000737:chemistry / Q000502:physiology; D008297:Male; D016202:N-Methylaspartate / Q000737:chemistry / Q000502:physiology*; D009490:Neurosecretory Systems / Q000502:physiology; D011374:Progesterone / Q000096:biosynthesis; D012098:Reproduction; D013237:Stereoisomerism; D013739:Testosterone / Q000096:biosynthesis
chemical_list: D007447:Invertebrate Hormones; D001224:Aspartic Acid; D007987:Gonadotropin-Releasing Hormone; D013739:Testosterone; D011374:Progesterone; D016202:N-Methylaspartate