In:
Journal of Applied Physiology, American Physiological Society, Vol. 115, No. 3 ( 2013-08-01), p. 394-402
Abstract:
All of the adaptations acquired through physical training are reversible with inactivity. Although significant reductions in maximal oxygen uptake (V̇o 2max ) 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% V̇o 2max ). 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.
Type of Medium:
Online Resource
ISSN:
8750-7587
,
1522-1601
DOI:
10.1152/japplphysiol.01272.2012
Language:
English
Publisher:
American Physiological Society
Publication Date:
2013
detail.hit.zdb_id:
1404365-8
SSG:
12
SSG:
31
