Agmatine (decarboxylated arginine) is synthesized and stored in astrocytes.
We investigated whether astrocytes store and synthesize agmatine (decarboxylated arginine), an endogenous ligand for imidazoline and alpha 2-adrenergic receptors, in brain. Agmatine, detected chemically and immunocytochemically, is contained in cultured astrocytes and C6 glioma cells (8.5 +/- 1.4 and 1.8 +/- 0.6 nmol mg-1 protein, respectively). Glial membranes express activity for arginine decarboxylase (ADC), the biosynthetic enzyme for agmatine (astrocytes 85.4 +/- 9.2; C6 cells 18.2 +/- 3.12 nmol h-1 mg-1 protein). Lipopolysaccharide, and inducer of glial nitric oxide synthase (iNOS), significantly reduced (C6) or did not affect (astrocytes) ADC activity. Inferferon-gamma, not affecting iNOS, elevated ADC activity in both cell types. Astrocytes are a site of synthesis and storage of agmatine. ADC and iNOS enzymes synthesizing distinct bioactive products from L-arginine, may be reciprocally regulated.
Department of Neurology and Neuroscience, Cornell University Medical College, New York, NY 10021, USA.
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S
Regunathan
D L
DL
Feinstein
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W
Raasch
D J
DJ
Reis
D000376:Agmatine / Q000378:metabolism*; D000818:Animals; D001253:Astrocytes / Q000378:metabolism*; D001932:Brain Neoplasms / Q000378:metabolism* / Q000473:pathology; D002262:Carboxy-Lyases / Q000378:metabolism*; D002478:Cells, Cultured; D002540:Cerebral Cortex / Q000166:cytology / Q000378:metabolism*; D005910:Glioma / Q000378:metabolism* / Q000473:pathology; D019001:Nitric Oxide Synthase / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley
D000376:Agmatine; D019001:Nitric Oxide Synthase; D002262:Carboxy-Lyases; C019722:arginine decarboxylase