Metabolic Consequences and Vulnerability to Diet-Induced Obesity in Male Mice under Chronic Social Stress
Figure 6
Vulnerability to high fat diet-induced obesity.
A) Body weight changes in the baseline and in stress phase. At baseline, when mice were fed standard diet, all experimental groups showed a decrease in body weight, while controls (Con) showed a slight increase (F(3,23) = 3.2, p<0.05). In the stress phase subordinates (Sub) and individually housed (Ind) mice were more, and dominant (Dom) were less, vulnerable to weight gain than Con (F(3,23) = 5.3, p<0.01). In the graph only statistical comparison with Con are shown. In addition, both Sub and Ind mice differed from Dom (p<0.001) and Sub differed from Ind on day 14 only (p<0.05). B) Food intake. When animals were fed a high fat diet they showed a marked increase in kcal ingested. However a clear difference emerged between experimental groups (F(6,32) = 2.9, p<0.05) with Dom and Ind showing sustained hyperphagia when compared to Con along the entire experiment. Sub were hyperphagic only in the third week while showing a trend in the second week of the stress phase. Finally Sub also differed from Ind and Dom in the first week of the stress phase (p<0.01). C) Food efficiency analysis revealed that while Con were able to maintain a balance trough the changing dietary environment, Sub and Ind but not Dom significantly increased food efficiency with HFD (F(9,69) = 5.1, p<0.0001). D) Visceral fat pad weight. Dom showed an overall lower amount of perigonadal (F(3,23) = 9.2, p<0.001), perirenal (F(3,23) = 2.5, p<0.08), retroperitoneal (F(3,23) = 3.7, p<0.05) and mesenteric (F(3,23) = 7.2, p<0.005) but not mediastinic fat pad weight when compared to Sub. Ind showed a robust increase in perigonadal, retroperitoneal and mesenteric adipose fat pads which was significant versus Con and Dom but not versus Sub. E) Cumulative weight of visceral fat mass. Dom showed lower overall visceral adipose tissue than Sub. On the contrary Ind differed from Con and Dom but not from Sub (F(3,23) = 8.4, p<0.001). * p<0.05 and **p<0.01 vs. Controls, § p<0.07 vs. Controls, ç p<0.01 vs. Con and Dom. #p<0.05 and ## p<0.01 vs. Basal level for each group. Arrows describe the change from standard to high fat diet.