Whole Body Periodic Acceleration Is an Effective Therapy to Ameliorate Muscular Dystrophy in mdx Mice

Abstract

Duchenne muscular dystrophy (DMD) is a genetic disorder caused by the absence of dystrophin in both skeletal and cardiac muscles. This leads to severe muscle degeneration, and dilated cardiomyopathy that produces patient death, which in most cases occurs before the end of the second decade. Several lines of evidence have shown that modulators of nitric oxide (NO) pathway can improve skeletal muscle and cardiac function in the mdx mouse, a mouse model for DMD. Whole body periodic acceleration (pGz) is produced by applying sinusoidal motion to supine humans and in standing conscious rodents in a headward-footward direction using a motion platform. It adds small pulses as a function of movement frequency to the circulation thereby increasing pulsatile shear stress to the vascular endothelium, which in turn increases production of NO. In this study, we examined the potential therapeutic properties of pGz for the treatment of skeletal muscle pathology observed in the mdx mouse. We found that pGz (480 cpm, 8 days, 1 hr per day) decreased intracellular Ca2+ and Na+ overload, diminished serum levels of creatine kinase (CK) and reduced intracellular accumulation of Evans Blue. Furthermore, pGz increased muscle force generation and expression of both utrophin and the carboxy-terminal PDZ ligand of nNOS (CAPON). Likewise, pGz (120 cpm, 12 h) applied in vitro to skeletal muscle myotubes reduced Ca2+ and Na+ overload, diminished abnormal sarcolemmal Ca2+ entry and increased phosphorylation of endothelial NOS. Overall, this study provides new insights into the potential therapeutic efficacy of pGz as a non-invasive and non-pharmacological approach for the treatment of DMD patients through activation of the NO pathway.

Contribution of TRPC Channels to Intracellular Ca2 + Dyshomeostasis in Smooth Muscle From mdx Mice

“…Striated muscle cells from DMD patients and mdx mice (Lopez et al, 1987;Altamirano et al, 2013Altamirano et al, , 2014Mijares et al, 2014) show elevated intracellular Ca 2+ and Na + . Therefore, intracellular [Ca 2+ ] and [Na + ] were measured in VSMCs isolated from Wt and mdx mice using double-barreled ion-specific microelectrodes.…”

“…Dystrophin is also present in the smooth muscle, playing a similar role than in skeletal muscle (North et al, 1993;Sharma et al, 2008). Deficiency of dystrophin in striated muscle cells results in alterations intracellular ion dyshomeostasis and muscle degeneration (Lopez et al, 1987;Danialou et al, 2001;Allen and Whitehead, 2011;Altamirano et al, 2012Altamirano et al, , 2014. In smooth muscle, the lack of dystrophin has been related with different alterations in the respiratory, gastrointestinal tract and the vascular bed (Miike et al, 1987;Barohn et al, 1988;Jaffe et al, 1990;Sun, 2015;Brown et al, 2018).…”

“…Our data show that quiescent VSMCs isolated from mdx mice have an intracellular Ca 2+ and Na + overload compared with nondystrophic Wt VSMCs. A substantial increase in [Ca 2+ ] i has been reported in intact skeletal muscle from DMD patients and an altered intracellular Ca 2+ and Na + homeostasis has been observed in the skeletal and cardiac muscle cells from mdx mice (Altamirano et al, 2014;Lopez et al, 2017Lopez et al, , 2018. Chronic elevation in [Ca 2+ ] i may activate hydrolytic enzymes (proteases, nucleases, and lipases), and subsequently compromise energy production, intracellular ion regulation, ROS production and ultimately result in cell death (Nicotera and Orrenius, 1998;Ascah et al, 2011;Altamirano et al, 2013Altamirano et al, , 2014Lopez et al, 2017).…”

“…While initial clinical manifestations of DMD are related to skeletal muscle weakness (Chakkalakal et al, 2005), the development of dilated cardiomyopathy occurs occasioning heart failure and death (Nigro et al, 1990) and a nonprogressive cognitive impairment has been observed in DMD patients (Bresolin et al, 1994;Anderson et al, 2002). Disturbance of intracellular [Ca 2+ ] has been reported in skeletal muscle from DMD patients (Lopez et al, 1987) and mdx mice (Turner et al, 1988;Altamirano et al, 2013Altamirano et al, , 2014, in cardiac cells from mdx mice (Mijares et al, 2014) and in cortical and hippocampal neurons isolated from mdx mice (Lopez et al, 2016).…”

Targeting angiogenesis in Duchenne muscular dystrophy

“…The role of eNOS (as well as nNOS) in vascular response in contracting fast-twitch skeletal muscle is well known [ 150 ]; however, the status of eNOS in DMD has not been well investigated and the results vary between different studies. In mdx mice, eNOS expression in skeletal muscles does not seem to be changed on mRNA level [ 83 ], but on protein level either no changes [ 151 , 152 ] or even elevation of eNOS was reported [ 153 ]. On the other hand, in a canine model of DMD, the vascular endothelial dysfunction with diminished eNOS protein level was reported [ 154 ].…”