Document Detail

The GABAergic-like system in the marine demosponge Chondrilla nucula.
MedLine Citation:
PMID:  17661369     Owner:  NLM     Status:  MEDLINE    
Gamma-amino butyric acid (GABA) is believed to be the principal inhibitory neurotransmitter in the mammalian central nervous system, a function that has been extended to a number of invertebrate systems. The presence of GABA in the marine demosponge Chondrilla nucula was verified using immunofluorescence detection and high-pressure liquid chromatography. A strong GABA-like immunoreactivity (IR) was found associated with choanocytes, exopinacocytes, endopinacocytes lining inhalant, and exhalant canals, as well as in archaeocytes scattered in the mesohyl. The capacity to synthesize GABA from glutamate and to transport it into the vesicles was confirmed by the presence in C. nucula of glutamate decarboxylase (GAD) and vesicular GABA transporters (vGATs), respectively. GAD-like and vGAT-like IR show the same distribution as GABA-like IR. Supporting the similarity between sponge and mammalian proteins, bands with an apparent molecular weight of about 65-67 kDa and 57 kDa were detected using antibodies raised against mammalian GAD and vGAT, respectively. A functional metabotropic GABA(B)-like receptor is also present in C. nucula. Indeed, both GABA(B) R1 and R2 isoforms were detected by immunoblot and immunofluorescence. Also in this case, IR was found in choanocytes, exopinacocytes, and endopinacocytes. The content of GABA in C. nucula amounts to 1225.75 +/- 79 pmol/mg proteins and GABA is released into the medium when sponge cells are depolarized. In conclusion, this study is the first indication of the existence of the GABA biosynthetic enzyme GAD and of the GABA transporter vGAT in sponges, as well as the first demonstration that the neurotransmitter GABA is released extracellularly.
Paola Ramoino; Lorenzo Gallus; Silvio Paluzzi; Luca Raiteri; Alberto Diaspro; Marco Fato; Giambattista Bonanno; Grazia Tagliafierro; Cristina Ferretti; Renata Manconi
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Microscopy research and technique     Volume:  70     ISSN:  1059-910X     ISO Abbreviation:  Microsc. Res. Tech.     Publication Date:  2007 Nov 
Date Detail:
Created Date:  2007-10-29     Completed Date:  2008-01-07     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  9203012     Medline TA:  Microsc Res Tech     Country:  United States    
Other Details:
Languages:  eng     Pagination:  944-51     Citation Subset:  IM    
Department for the Study of the Territory and its Resources, University of Genoa, 16132 Genova, Italy.
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MeSH Terms
Biological Transport, Active
Chromatography, High Pressure Liquid
Fluorescent Antibody Technique
Glutamate Decarboxylase / metabolism
Porifera / physiology*
Protein Isoforms / metabolism
gamma-Aminobutyric Acid / physiology*
Reg. No./Substance:
0/Protein Isoforms; 56-12-2/gamma-Aminobutyric Acid; EC Decarboxylase

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