Figure 3.

The Effect of β-GPA Feeding on AMPK and Mitochondrial Biogenesis in Young and Old Rats

(A) AMPK-α₂ activity in the EDL muscle of young and old rats fed either a β-GPA-supplemented diet or a control diet. The β-GPA-supplemented diet resulted in a 146% increase in AMPK-α₂ activity in the young rats. In contrast, the β-GPA-supplemented diet had no effect on AMPK-α₂ activity in the old rats. (n = 3–4 in each group.) ^∗p < 0.01.

(B) Pgc-1α mRNA expression in the EDL muscle of young and old rats fed either a β-GPA-supplemented diet or a control diet. Pgc-1α mRNA expression increased by 86% in the young β-GPA-fed rats. In contrast, there was no difference in Pgc-1α mRNA expression in the old rats. (n = 5–8 in each group.) ^∗p < 0.05.

(C) Percent increase in mitochondrial density in the EDL muscle of young and old rats fed a β-GPA-supplemented diet compared to control rats. Mitochondrial density increased by 38% in the young β-GPA-fed rats. In contrast, the β-GPA-supplemented diet resulted in no difference in mitochondrial density in the old rats. (n = 4–5 in each group.) ^∗p < 0.05.

(D) δ-Alas mRNA expression in the EDL muscle of young and old rats fed either a β-GPA-supplemented diet or a control diet. δ-Alas mRNA expression increased by 289% in the young β-GPA-fed rats. In contrast, there was no difference in δ-Alas mRNA expression in the old rats. (n = 3–8 in each group.) ^∗p = 0.05.

(E) Cytochrome c protein expression in the EDL muscle of young and old rats fed either a β-GPA-supplemented diet or a control diet. Cytochrome c protein expression increased by 76% in the young β-GPA-fed rats. In contrast, there was no difference in cytochrome c protein expression in the old rats. (n = 4–8 in each group.) ^∗p < 0.05 .