Age-Related Changes in Rat Adipose Tissue Cellularity Are Altered by Dietary Restriction and Exercise

Abstract

This study examined the effects of diet restriction and exercise training during aging on adipocyte size and number in male Wistar rats. An average of 30 weanling rats each were assigned to one of four experimental groups: ad libitum access to food, nonexercised; diet restricted, nonexercised; ad libitum access to food, exercised; diet restricted, exercised. Diet-restricted groups were allowed free access to food every other day, and, over the course of the study, they consumed 18-25% less than the groups allowed ad libitum access. Exercise training consisted of swimming on alternate days for up to 3 h per exercise period. Fat cell size, number and fat depot mass were determined in the inguinal, epididymal and perirenal fat depots at 12 mo of age and every 4 mo thereafter until 28 mo of age. Fat cell number was not influenced by age, exercise or food restriction in the epididymal or perirenal fat depots. Inguinal cell number was lower (P < 0.05) in the diet-restricted, exercised group at all ages compared with all other treatments. Dietary restriction and exercise training significantly decreased fat depot mass and fat cell size, with dietary restriction having the greatest effect. A bimodal distribution of adipocytes was observed in the epididymal, perirenal and inguinal depots of animals allowed ad libitum access to food. The presence of a large population of small fat cells (< 35 microns) indicated that even in the very aged animal there was the propensity for large variations in fat pad mass. The influence of diet restriction, exercise and aging on adipocyte cell size was highly variable and these effects were dependent on adipose tissue depot location.

Adaptation to lactation in OLETF rats lacking CCK-1 receptors: body weight, fat tissues, leptin and oxytocin

“…Leptin levels were highly correlated with OLETF body weight, fat mass and adipocyte size ( Table 2). In general, Bailey 33 reported that I-WAT mass decreased as a function of both reduced size and number of fat cells, following exercise. Thus, this tissue appears to be an energy reservoir that responds to the body's energetic needs, not only after exercise, but also in lactation.…”

“…[33][34] However, an increase can be observed in genetically obese adult animals, in response to various manipulations. 33 The inguinal fat pad is distinct from other fat depot types, as both adipocyte cell size and number can be affected by food consumption and reproductive status. 33 For this reason we further investigated the size of inguinal adipocytes.…”

“…33 The inguinal fat pad is distinct from other fat depot types, as both adipocyte cell size and number can be affected by food consumption and reproductive status. 33 For this reason we further investigated the size of inguinal adipocytes.…”

Divergent regulation of adipose tissue metabolism by calorie restriction and inhibition of growth hormone signaling

“…Indeed, Li and colleagues (Li et al 2003) have reported that the responsiveness of lipid metabolism-related genes to fasting is more sensitive in visceral fat (including peri-renal and epididymal fat pads), and is almost unchanged in subcutaneous fat in rats. In male Wistar rats subjected to alternate-day feeding for CR, it was reported that the peri-renal fat and the epididymal fat pads, but not the inguinal fat pad, show similar age-and CR-related changes in fat cell size and number (Bailey et al, 1993). In our previous study using the epididymal fat pad in male F344 rats , the p-Akt/PKC-Glut4 pathway was upregulated at baseline in CR rats.…”

Estudo morfoquantitativo e imunohistoquímico da cartilagem articular do joelho de ratos Wistar submetidos à restrição calórica no envelhecimento

“…Os dados encontrados em relação ao grupo SR confirmam os achados da literatura, que demonstram que o processo natural do envelhecimento causa aumento de massa em ratos até meados dos 20 meses de idade (BAILEY et al, 1993;HOLLOSZY, 1997;ATHANASIOU et al, 2000;WANG et al, 2006).…”