Evidence for a functional nitric oxide synthase system in brown adipocyte nucleus.
The intracellular localization and activity of the nitric oxide synthase (NOS) isoforms were investigated in rat brown adipocytes. Immunohistochemistry showed cytoplasmic and nuclear staining for the endothelial NOS (eNOS) and inducible NOS (iNOS) isoforms; accordingly, anti-L-citrulline antibody, a marker of NOS activity, immunostained both the cytoplasm and the nucleus. The presence of metabolically active NOS in the nucleus was further confirmed by immunoblotting analyses of subcellular fractions of homogenates from cultured brown adipocytes and by measurements of NOS activity in the cytosol and nucleus. Sympathetic stimulation in vivo (i.e. cold exposure or beta(3)-adrenergic agonist treatment) and in vitro (i.e. noradrenaline treatment of cultured cells) significantly increased both cytosolic and nuclear eNOS and iNOS expression and activities. By contrast, the number of iNOS-positive, but not eNOS-positive, nuclei was significantly lower in the functionally impaired brown fat of genetically obese Zucker fa/fa rats. These data suggest the existence of a noradrenaline-modulated functional NOS system in the nucleus of brown adipocytes.
Giordano
Antonio
A
Institute of Normal Human Morphology, Faculty of Medicine, University of Ancona, Ancona, Italy.
Tonello
Cristina
C
Bulbarelli
Alessandra
A
Cozzi
Valeria
V
Cinti
Saverio
S
Carruba
Michele O
MO
Nisoli
Enzo
E
D017667:Adipocytes / Q000737:chemistry / Q000166:cytology / Q000187:drug effects / Q000201:enzymology*; D002001:Adipose Tissue, Brown / Q000737:chemistry / Q000166:cytology / Q000187:drug effects / Q000201:enzymology*; D000316:Adrenergic alpha-Agonists / Q000494:pharmacology; D000318:Adrenergic beta-Agonists / Q000494:pharmacology; D000818:Animals; D015153:Blotting, Western; D002467:Cell Nucleus / Q000737:chemistry / Q000187:drug effects / Q000201:enzymology*; D003080:Cold Temperature; D003600:Cytosol / Q000737:chemistry / Q000201:enzymology; D007150:Immunohistochemistry; D007527:Isoenzymes; D008297:Male; D019001:Nitric Oxide Synthase / Q000032:analysis / Q000378:metabolism*; D052247:Nitric Oxide Synthase Type II; D052250:Nitric Oxide Synthase Type III; D009765:Obesity / Q000201:enzymology; D051381:Rats; D017207:Rats, Sprague-Dawley; D011924:Rats, Zucker; D013347:Subcellular Fractions / Q000737:chemistry / Q000201:enzymology
D000316:Adrenergic alpha-Agonists; D000318:Adrenergic beta-Agonists; D007527:Isoenzymes; D019001:Nitric Oxide Synthase; D052247:Nitric Oxide Synthase Type II; D052250:Nitric Oxide Synthase Type III; C496318:Nos2 protein, rat; C496316:Nos3 protein, rat