TNF and chronic obstructive pulmonary disease: Interestingly, the levels of TNF-α in either serum or skeletal muscle tissue in the COPD model rats that were treated with resveratrol and AICAR were lower than those in COPD rats that received saline treatment (Figure 5), although we also noticed that the levels of TNF-α in the AICAR-treated rats were lower than those from the rats that were treated with resveratrol (Figure 5), yet the mechanisms need to be further studied.