Abstract
Non-alcoholic fatty liver disease (NAFLD) represents a continuum that begins with accumulation of lipid in hepatic cells progressing to hepatic steatosis with inflammation (steatohepatitis), fibrosis, and cirrhosis. Weight-loss using dietary modification and physical activity are common strategies used for the treatment of NAFLD; however, it remains to be determined the effects of physical activity on hepatic inflammation during weight-loss. The purpose of this study was to determine the therapeutic role of physical activity on plasma and hepatic inflammatory markers during weight-loss. Male C57BL/6 mice were fed either a low-fat (LFD; 10% kcal fat) or high-fat (HFD; 60% kcal fat) diet for 10-weeks. Following 10-weeks, the HFD group was randomly assigned to either a LFD (Diet) or LFD with physical activity (Diet+PA) to induce weight loss for 8-weeks. After 8-weeks, reductions in body mass were observed in both Diet and Diet+PA groups (see Table 1.). Interestingly, the Diet+PA group lost significantly (P<0.05) more body mass than the Diet group. Despite significant (P<0.05) reductions in body mass and HOMA-IR, plasma TNF-α remained elevated in the Diet and Diet+PA groups. Moreover, Diet+PA plasma TNF-α was significantly (P<0.05) greater than the HFD obese controls. Elevated plasma TNF-α in the Diet+PA was matched by a greater hepatic expression of IL-1β and IL-6 mRNA when compared to all groups. Interestingly, the expression of TGF-β1 mRNA was significantly (P<0.05) reduced in the Diet+PA when compared to all groups. The elevated plasma TNF-α and expression of IL-1β and IL-6 mRNA are likely due to physical activity. It remains unclear as to the pro-inflammatory effects of physical activity during weight-loss; however, this may be part of a protective adaption to regular exercise. Furthermore, the reduced hepatic TGF-β1 mRNA levels suggest a protective strategy against fibrogenesis in the spectrum of liver disease.
Table 1. Whole body and hepatic metabolic characteristics following weight-loss.
Variables
LFD (n=12)
HFD (n=12)
Diet (n=12)
Diet+PA (n=12)
Body mass (g)
30.2 ± 1.1
48.8 ± 0.5*
30.3 ± 0.7†
26.1 ± 0.3*,†,‡
HOMA-IR
22.9 ± 1.2
187.3 ± 7.5*
19.4 ± 8.8†
25.3 ± 10.5†
IL-6 (pg/mL)
6.4 ± 0.7
6.2 ± 1.0
5.9 ± 0.9
6.4 ± 0.9
TNF-α (pg/mL)
30.8 ± 6.7
60.6 ± 5.3*
74.0 ± 8.1*
82.5 ± 7.7*,†
IL-1β mRNA
1.00 ± 0.51
0.97 ± 0.34
1.20 ± 0.59
2.83 ± 0.62*,†,‡
IL-6 mRNA
1.00 ± 0.45
1.53 ± 0.50
1.16 ± 0.72
2.36 ± 0.55*,†,‡
TNF-α mRNA
1.00 ± 0.09
0.89 ± 0.08
0.94 ± 0.14
0.83 ± 0.06
TGF-β1 mRNA
1.00 ± 0.06
1.02 ± 0.06
1.02 ± 0.10
0.84 ± 0.05†
Note. Data are presented as mean ± SEM. *Significantly (P<0.05) different than LFD; †significantly (P<0.05) different than HFD; ‡significantly (P<0.05) different than Diet.
Recommended Citation
Seija, Andrew; Poole, Kaylee E.; Eck, Kevin; Harris, Matthew; Nick, Tayler N.; and Wooten, Joshua S.
(2015)
"The Effects of Physical Activity on Markers of Hepatic Inflammation During Weight-Loss,"
International Journal of Exercise Science: Conference Proceedings: Vol. 2:
Iss.
7, Article 78.
Available at:
https://digitalcommons.wku.edu/ijesab/vol2/iss7/78