The Dietary Supplement Protandim® Decreases Plasma Osteopontin and Improves Markers of Oxidative Stress in Muscular Dystrophy Mdx Mice

ABSTRACT.

Therapeutic options for Duchenne muscular dystrophy (DMD), the most common and lethal neuromuscular disorder in children, remain elusive. Oxidative damage is implicated as a pertinent factor involved in its pathogenesis. Protandim® is an over-the-counter supplement with the ability to induce antioxidant enzymes. In this study we investigated whether Protandim® provided benefit using surrogate markers and functional measures in the dystrophin-deficient (mdx) mouse model of DMD. Male 3-week-old mdx mice were randomized into two treatment groups: control (receiving standard rodent chow) and Protandim®-supplemented standard rodent chow. The diets were continued for 6-week and 6-month studies. The endpoints included the oxidative stress marker thiobarbituric acid-reactive substances (TBARS), plasma osteopontin (OPN), plasma paraoxonase (PON1) activity, H&E histology, gadolinium-enhanced magnetic resonance imaging (MRI) of leg muscle and motor functional measurements. The Protandim® chow diet in mdx mice for 6 months was safe and well tolerated. After 6 months of Protandim®, a 48% average decrease in plasma TBARS was seen; 0.92 nmol/mg protein in controls versus 0.48 nmol/mg protein in the Protandim® group (p = .006). At 6 months, plasma OPN was decreased by 57% (p = .001) in the Protandim®-treated mice. Protandim® increased the plasma antioxidant enzyme PON1 activity by 35% (p = .018). After 6 months, the mdx mice with Protandim® showed 38% less MRI signal abnormality (p = .07) than mice on control diet. In this 6-month mdx mouse study, Protandim® did not significantly alter motor function nor histological criteria.

KEYWORDS. :

• Duchenne muscular dystrophy
• protandim®
• mdx mice
• dystrophin
• dystrophic muscle
• paraoxonase
• osteopontin
• oxidative stress