Abstract
Rationale and Objectives:
We aimed to evaluate the effect of exercise on brown adipose tissue (BAT) volumes and T2 values in mice.
Materials and Methods
Twenty-five female Kunming mice were divided into two groups, a running group (n = 5) and a control group (n = 20). After 4 months, all magnetic resonance imaging (MRI) scans of mice were performed on a 7 Tesla (7T) MR scanner with T2-weighted imaging (T2WI) and a T2 mapping sequence. Interscapular brown adipose tissue (BAT) volumes and T2 values were measured. To reduce the impact of weight on the results, we compared the ratio of BAT volumes to body weights (V/W). The data are expressed as mean ± SD, the BAT V/W and T2 values were compared between the control and running groups using the Wilcoxon rank-sum test, P < 0.05 were considered statistically significant.
Results
Interscapular BAT volumes of the running group (n = 5) and control group (n = 20) were (180.09ml ± 59.80 ml) and (99.98ml ± 35.05ml), respectively. The V/W ratios of the running and control groups were (3.83ml/g ± 0.78ml/g) and (2.17ml/g ± 0.56ml/g), respectively. Interscapular BAT T2 values of the running and control groups were (76.07ms ± 10.82ms) and (61.22ms ± 15.98ms), respectively. Significant differences were found in the BAT V/W ratios (P = 0.0003, P < 0.001) and T2 values between the two groups (P = 0.0096, P < 0.05). BAT volume correlated positively with BAT T2 value (r = 0.75, p = 0.00002).
Conclusions
MRI is a non-invasive and quantitative method for identifying BAT, especially at ultra-high field like 7T. Long-term running increases BAT volume and T2 value, what's more, BAT volume correlates positively with BAT T2 value.
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