L-arginine uptake, the citrulline-NO cycle and arginase II in the rat brain: an in situ hybridization study.
Nitric oxide (NO) is synthesized from a unique precursor, arginine, by nitric oxide synthase (NOS). In brain cells, arginine is supplied by protein breakdown or extracted from the blood through cationic amino acid transporters (CATs). Arginine can also be recycled from the citrulline produced by NOS activity, through argininosuccinate synthetase (AS) and argininosuccinate lyase (AL) activities, and metabolized by arginase. NOS, AS and AL constitute the so-called citrulline-NO cycle. In order to better understand arginine transport, recycling and degradation, we studied the regional distribution of cells expressing CAT1, CAT3, AS, AL, neuronal NOS (nNOS) and arginase II (AII) in the adult rat brain by non-radioisotopic in situ hybridization (ISH). CAT1, AL and AII presented an ubiquitous neuronal and glial expression, whereas CAT3 and AS were confined to neurons. nNOS was restricted to scattered neurons and a few brain nuclei and layers. We demonstrate by this study that cells expressing nNOS all appear to express the entire citrulline-NO cycle, whereas numerous cells expressing AL do not express AS. The differential expression of these genes within the same anatomical structure could indicate that intercellular exchanges of citrulline-NO cycle metabolites are relevant. Thus vicinal interactions should be taken into account to study their regulatory mechanisms.
Braissant
O
O
Central Clinical Chemistry Laboratory, University Hospital, CH-1011, Lausanne, Switzerland. olivier.braissant@chuv.hospvd.ch
Gotoh
T
T
Loup
M
M
Mori
M
M
Bachmann
C
C
D026923:Amino Acid Transport Systems, Basic; D000818:Animals; D001119:Arginase / Q000235:genetics* / Q000378:metabolism*; D001120:Arginine / Q000378:metabolism*; D001123:Argininosuccinate Lyase / Q000235:genetics / Q000378:metabolism; D001124:Argininosuccinate Synthase / Q000235:genetics / Q000378:metabolism; D001921:Brain / Q000378:metabolism*; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism; D002956:Citrulline / Q000378:metabolism*; D017403:In Situ Hybridization / Q000379:methods; D008297:Male; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism; D009419:Nerve Tissue Proteins / Q000235:genetics / Q000378:metabolism; D009474:Neurons / Q000378:metabolism; D009569:Nitric Oxide / Q000378:metabolism*; D019001:Nitric Oxide Synthase / Q000378:metabolism; D009928:Organ Specificity; D051381:Rats; D017207:Rats, Sprague-Dawley
D026923:Amino Acid Transport Systems, Basic; D002352:Carrier Proteins; D008565:Membrane Proteins; D009419:Nerve Tissue Proteins; C105348:Slc7a3 protein, rat; D002956:Citrulline; D009569:Nitric Oxide; D001120:Arginine; D019001:Nitric Oxide Synthase; C113162:Arg2 protein, rat; D001119:Arginase; D001123:Argininosuccinate Lyase; D001124:Argininosuccinate Synthase