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Influence of regular physical activity and caloric restriction on β‐adrenergic and natriuretic peptide receptor expression in retroperitoneal adipose tissue of OLETF rats
Author(s) -
Jenkins Nathan T.,
Padilla Jaume,
Rector R. Scott,
Laughlin M. Harold
Publication year - 2013
Publication title -
experimental physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.925
H-Index - 101
eISSN - 1469-445X
pISSN - 0958-0670
DOI - 10.1113/expphysiol.2013.074658
Subject(s) - medicine , endocrinology , adipose tissue , sed , atrial natriuretic peptide , natriuretic peptide , npr2 , receptor , lipolysis , adrenergic , white adipose tissue , brown adipose tissue , heart failure
New findings• What is the central question of this study? What are the effects of caloric restriction and chronic exercise on β‐adrenergic and natriuretic peptide receptor genes in visceral adipose tissue of obese rats? • What is the main finding and its importance? Physical activity induced increases in natriuretic peptide receptor (NPR) and β‐adrenergic receptor (βAR) mRNA levels in retroperitoneal fat of obese rats. Both chronic exercise and caloric restriction enhance protein expression of βAR2 and βAR3 in the retroperitoneal adipose tissue of the Otsuka Long–Evans Tokushima Fatty rat, albeit through apparently different mechanisms. Organ culture experiments support the hypothesis that increases in nitric oxide interact synergistically with adrenaline and atrial natriuretic peptide signalling in control of the expression of βAR2 and NPR2 mRNAs.The mechanisms underlying exercise‐induced increases in adipose tissue blood flow and lipolysis involve both β‐adrenergic receptor (βAR)‐ and natriuretic peptide receptor (NPR)‐dependent processes. We hypothesized that daily wheel running (RUN) would increase the expression of NPR1, NPR2, βAR2 and βAR3 in retroperitoneal (RP) and epididymal (EPI) adipose tissues of obese Otsuka Long–Evans Tokushima Fatty (OLETF) rats. Four‐week‐old OLETF rats were assigned to sedentary (SED, n = 6), calorie‐restricted (CR, n = 8; fed 70% of SED) or RUN groups ( n = 8). Rats were killed at 40 weeks of age. By design, body weight and adiposity were similar between RUN and CR animals, but each was lower than SED ( P < 0.01). Compared with SED, RP depots of RUN rats exhibited 1.7‐ to 3.2‐fold greater NPR1, NPR2, βAR2 and βAR3 mRNA levels (all P < 0.05). There were no differences between CR and SED in the expression of these genes in RP adipose tissues, and there were no differences in gene expression among groups in EPI adipose tissues. At the protein level, βAR2 and βAR3 were elevated in RUN and CR groups relative to the SED group in RP adipose tissues. In order to gain insight into the mechanisms underlying the activity‐induced increases in NPR and βAR mRNAs, RP adipose tissue explants from Wistar rats were treated with atrial natriuretic peptide (ANP), adrenaline and/or S ‐nitroso‐ N ‐acetyl‐ dl ‐penicillamine (SNAP; a nitric oxide donor) in organ culture experiments. SNAP synergistically enhanced adrenaline‐ and ANP‐stimulated increases in NPR2 and βAR2 mRNA levels. Our data suggest that physical activity‐induced increases in nitric oxide interact with adrenaline and ANP to trigger the induction of NPR and βAR mRNAs in the RP adipose tissue depot of the OLETF rat.