The impact of a high-fat diet in mice is dependent on duration and age, and differs between muscles

Abstract

Prolonged high-fat diets (HFDs) can cause intramyocellular lipid (IMCL) accumulation that may negatively affect muscle function. We investigated the duration of a HFD required to instigate these changes, and whether the effects are muscle specific and aggravated in older age. Muscle morphology was determined in the soleus, extensor digitorum longus (EDL) and diaphragm muscles of female CD-1 mice from 5 groups: young fed a HFD for 8 weeks (YS-HFD, n=16), young fed a HFD for 16 weeks (YL-HFD, n=28) and young control (Y-Con, n=28). The young animals were 20 weeks old at the end of the experiment. Old (70 weeks) female CD-1 mice received either a normal diet (O-Con, n=30) or a HFD for 9 weeks (OS-HFD, n=30). Body mass, body mass index and intramyocellular lipid (IMCL) content increased in OS-HFD (P≤0.003). In the young mice, this increase was seen in YL-HFD and not YS-HFD (P≤0.006). The soleus and diaphragm fibre cross-sectional area (FCSA) in YL-HFD was larger than that in Y-Con (P≤0.004) while OS-HFD had a larger soleus FCSA compared with that of O-Con after only 9 weeks on a HFD (P<0.001). The FCSA of the EDL muscle did not differ significantly between groups. The oxidative capacity of fibres increased in young mice only, irrespective of HFD duration (P<0.001). High-fat diet-induced morphological changes occurred earlier in the old animals than in the young, and adaptations to HFD were muscle specific, with the EDL being least responsive.

Methionine restriction plus overload improves skeletal muscle and metabolic health in old mice on a high fat diet

“…It is interesting to note that although a HFD led to a lower amount of food intake, the caloric intake was elevated in both young and old mice. Similar to previous observations the higher caloric intake was accompanied by an increase in body mass 29 . It was somewhat surprising, however, that the increase in body mass was greater in young than old mice, as in a previous study old mice had a larger gain in body mass 29 .…”

“…Similar to previous observations the higher caloric intake was accompanied by an increase in body mass 29 . It was somewhat surprising, however, that the increase in body mass was greater in young than old mice, as in a previous study old mice had a larger gain in body mass 29 . The discrepancy may be attributable to the duration of HFD, as it has been observed that old mice become more easily obese than young in response to a short-term HFD, whereas chronic HFD feeding causes greater body mass increase in young than old mice 30 .…”

“…Somewhat unexpected is the observation that HFD did not impair glucose tolerance in either young or old mice, given that a HFD is a risk factor for the development of insulin resistance 38 , 39 . It is possible that the duration of the HFD plays a role, as it has been observed that the glucose intolerance was more pronounced after 12 than 4 weeks of HFD 40 and at least in young-adult mice the accumulation of intramyocellular fat did occur after 16 weeks, but not after 8 weeks on a HFD 29 . Other studies, however, have seen impaired insulin sensitivity as soon as after 8 weeks of a HFD 41 that may result in impaired glucose tolerance.…”

Dietary Energy Partition: The Central Role of Glucose

“…Limit the processing of fatty acids to 2C fragments and thus dump them as TAG (with a token 3C glycerol) [ 200 ]. This process induces obesity [ 201 ], steatosis [ 202 ], and drives muscle to be essentially a fat-infiltrated 2C energy user, with glucose intolerance [ 203 , 204 ].…”

Analysis of the area and the number of pulmonary alveoli through the normal aging process in CD1 mouse

“…Although the mouse strain CD1 has been widely used to examine multiple aspects of the general aging process [15][16][17], its alveolar morphometric analysis has not been reported yet.…”