title: Cessation of physical exercise changes metabolism and modifies the adipocyte cellularity of the periepididymal white adipose tissue in rats.
abstract: All of the adaptations acquired through physical training are reversible with inactivity. Although significant reductions in maximal oxygen uptake (Vo2max) can be observed within 2 to 4 wk of detraining, the consequences of detraining on the physiology of adipose tissue are poorly known. Our aim was therefore to investigate the effects of discontinuing training (physical detraining) on the metabolism and adipocyte cellularity of rat periepididymal (PE) adipose tissue. Male Wistar rats, aged 6 wk, were divided into three groups and studied for 12 wk under the following conditions: 1) trained (T) throughout the period; 2) detrained (D), trained during the first 8 wk and detrained during the remaining 4 wk; and 3) age-matched sedentary (S). Training consisted of treadmill running sessions (1 h/day, 5 days/wk, 50-60% Vo2max). The PE adipocyte size analysis revealed significant differences between the groups. The adipocyte cross-sectional area (in μm(2)) was significantly larger in D than in the T and S groups (3,474 ± 68.8; 1,945.7 ± 45.6; 2,492.4 ± 49.08, respectively, P < 0.05). Compared with T, the isolated adipose cells (of the D rats) showed a 48% increase in the ability to perform lipogenesis (both basal and maximally insulin-stimulated) and isoproterenol-stimulated lipolysis. No changes were observed with respect to unstimulated lipolysis. A 15% reduction in the proportion of apoptotic adipocytes was observed in groups T and D compared with group S. The gene expression levels of adiponectin and PPAR-gamma were upregulated by factors of 3 and 2 in D vs. S, respectively. PREF-1 gene expression was 3-fold higher in T vs. S. From these results, we hypothesize that adipogenesis was stimulated in group D and accompanied by significant adipocyte hypertrophy and an increase in the lipogenic capacity of the adipocytes. The occurrence of apoptotic nuclei in PE fat cells was reduced in the D and T rats; these results raise the possibility that the adipose tissue changes after detraining are obesogenic.
authors.affiliation: Department of Physiology and Biophysics, Institute of Biomedical Sciences, University of Sao Paulo, Sao Paulo, Brazil.
authors.forename: Rogerio A L
authors.initials: RA
authors.lastname: Sertie
authors.forename: Sandra
authors.initials: S
authors.lastname: Andreotti
authors.forename: André R G
authors.initials: AR
authors.lastname: Proença
authors.forename: Amanda B
authors.initials: AB
authors.lastname: Campana
authors.forename: Thais M
authors.initials: TM
authors.lastname: Lima-Salgado
authors.forename: Miguél L
authors.initials: ML
authors.lastname: Batista
authors.forename: Marilia C L
authors.initials: MC
authors.lastname: Seelaender
authors.forename: Rui
authors.initials: R
authors.lastname: Curi
authors.forename: Ariclecio C
authors.initials: AC
authors.lastname: Oliveira
authors.forename: Fabio B
authors.initials: FB
authors.lastname: Lima
mesh_terms: D017667:Adipocytes / Q000378:metabolism*; D052242:Adiponectin / Q000096:biosynthesis; D052436:Adipose Tissue, White / Q000166:cytology* / Q000378:metabolism*; D000818:Animals; D002469:Cell Separation; D048429:Cell Size; D002843:Chromatin / Q000378:metabolism; D002950:Citrate (si)-Synthase / Q000378:metabolism; D064429:Fatty Acid Synthases / Q000378:metabolism; D005230:Fatty Acids, Nonesterified / Q000097:blood; D005947:Glucose / Q000378:metabolism; D005954:Glucosephosphate Dehydrogenase / Q000378:metabolism; D007328:Insulin / Q000097:blood; D036341:Intercellular Signaling Peptides and Proteins / Q000096:biosynthesis; D008066:Lipolysis / Q000502:physiology; D008291:Malate Dehydrogenase / Q000378:metabolism; D008297:Male; D008565:Membrane Proteins / Q000096:biosynthesis; D024101:Mitochondrial Proteins / Q000096:biosynthesis; D018482:Muscle, Skeletal / Q000378:metabolism; D047495:PPAR gamma / Q000096:biosynthesis; D010805:Physical Conditioning, Animal / Q000502:physiology*; D051381:Rats; D017208:Rats, Wistar; D013739:Testosterone / Q000378:metabolism; D014157:Transcription Factors / Q000096:biosynthesis
chemical_list: D052242:Adiponectin; D002843:Chromatin; C512923:Dlk1 protein, rat; D005230:Fatty Acids, Nonesterified; D007328:Insulin; D036341:Intercellular Signaling Peptides and Proteins; D008565:Membrane Proteins; D024101:Mitochondrial Proteins; D047495:PPAR gamma; C559221:TFB2M protein, rat; D014157:Transcription Factors; D013739:Testosterone; D008291:Malate Dehydrogenase; D005954:Glucosephosphate Dehydrogenase; C034544:D-malate dehydrogenase (decarboxylating); D064429:Fatty Acid Synthases; D002950:Citrate (si)-Synthase; D005947:Glucose
keywords: adipogenesis; adipose tissue; apoptosis; lipogenesis; lipolysis