Different modulation by dietary restriction of adipokine expression in white adipose tissue sites in the rat.
BACKGROUND
White adipose tissue (WAT) is a disperse organ acting as energy storage depot and endocrine/paracrine controlling factor in the management of energy availability and inflammation. WAT sites response under energy-related stress is not uniform. In the present study we have analyzed how different WAT sites respond to limited food restriction as a way to better understand the role of WAT in the pathogenesis of the metabolic syndrome.


METHODS
Overweight male rats had their food intake reduced a 40% compared with free-feeding controls. On day ten, the rats were killed; circulating glucose, insulin, leptin, adiponectin, triacylglycerols and other parameters were measured. The main WAT sites were dissected: mesenteric, retroperitoneal, epididymal and subcutaneous inguinal, which were weighed and frozen. Later all subcutaneous WAT was also dissected and weighed. Samples were used for DNA (cellularity) analysis and mRNA extraction and semiquantitarive RT-PCR analysis of specific cytokine gene expressions.


RESULTS
There was a good correlation between serum leptin and cumulative WAT leptin gene mRNA, but not for adiponectin. Food restriction reduced WAT size, but not its DNA content (except for epididymal WAT). Most cytokines were correlated to WAT site weight, but not to DNA. There was WAT site specialization in the differential expression (and probably secretion) of adipokines: subcutaneous WAT showed the highest concentration for leptin, CD68 and MCP-1, mesenteric WAT for TNFalpha (and both tissues for the interleukins 1beta and 6); resistin was highly expressed in subcutaneous and retroperitoneal WAT.


CONCLUSIONS
Food restriction induced different patterns for mesenteric and the other WAT sites, which may be directly related to both the response to intestine-derived energy availability, and an inflammatory-related response. However, retroperitoneal WAT, and to a lower extent, subcutaneous and epididymal, reacted decreasing the expression of inflammatory markers and the signaling of decreased energy availability in their stores. The varying cytokine expression patterns highlight the fact that WAT sites show different inflammatory and signaling responses to energy availability; they are too much different to simply extend to the whole-body WAT the findings of one or even a couple of sites.
Romero
María del Mar
Mdel M
Department of Nutrition and Food Science, Faculty of Biology, University of Barcelona, Barcelona, Spain. marromero@ub.edu
Fernández-López
José Antonio
JA
Esteve
Montserrat
M
Alemany
Marià
M
D054392:Adipokines / Q000096:biosynthesis* / Q000235:genetics; D052242:Adiponectin / Q000096:biosynthesis / Q000235:genetics; D052436:Adipose Tissue, White / Q000378:metabolism*; D000818:Animals; D015703:Antigens, CD / Q000096:biosynthesis / Q000235:genetics; D015214:Antigens, Differentiation, Myelomonocytic / Q000096:biosynthesis / Q000235:genetics; D001786:Blood Glucose / Q000032:analysis; D002352:Carrier Proteins; D016207:Cytokines / Q000096:biosynthesis / Q000235:genetics; D005508:Food Deprivation; D005786:Gene Expression Regulation; D007249:Inflammation / Q000378:metabolism; D007328:Insulin / Q000097:blood; D020738:Leptin / Q000378:metabolism; D008297:Male; D054409:Nicotinamide Phosphoribosyltransferase / Q000096:biosynthesis / Q000235:genetics; D009928:Organ Specificity; D050177:Overweight / Q000178:diet therapy / Q000378:metabolism; D000070778:Perilipin-1; D010750:Phosphoproteins / Q000096:biosynthesis / Q000235:genetics; D012333:RNA, Messenger / Q000096:biosynthesis; D011897:Random Allocation; D051381:Rats; D052243:Resistin / Q000096:biosynthesis / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014280:Triglycerides / Q000097:blood; D000097382:CD68 Molecule
D054392:Adipokines; D052242:Adiponectin; D015703:Antigens, CD; D015214:Antigens, Differentiation, Myelomonocytic; D001786:Blood Glucose; D002352:Carrier Proteins; D016207:Cytokines; D007328:Insulin; D020738:Leptin; D054409:Nicotinamide Phosphoribosyltransferase; D000070778:Perilipin-1; D010750:Phosphoproteins; D012333:RNA, Messenger; D052243:Resistin; D014280:Triglycerides; C539355:CD68 protein, rat; D000097382:CD68 Molecule; C499622:Retn protein, rat; C504970:nicotinamide phosphoribosyltransferase, rat