MusculoskeletalMelatonin Attenuates I/R-Induced Mitochondrial Dysfunction in Skeletal Muscle
Introduction
Our previous studies 1, 2 have shown that prolonged ischemia followed by reperfusion not only induces necrosis but also accelerates apoptosis in the cells of skeletal muscle. Mitochondria are essential for cell survival, because of their roles as generators of energy as well as regulators of cell death [3]. Mitochondria are a major source of reactive oxygen species (ROS) that could be the toxic stimuli produced during reperfusion and the key components of I/R injury 4, 5. Our previous study [6] found that ischemia/reperfusion (I/R) causes a significant mitochondrial dysfunction, which could be an underlying mechanism of I/R-induced cell death. The present study is the continuation of our long-term project focused on I/R injury in skeletal muscle.
Melatonin (N-acetyl-5-methoxytryptamine), released from the pineal gland, is a highly efficient scavenger of ROS [7]. The highest melatonin concentrations are found in the mitochondria 8, 9, 10. Mitochondria have been identified as a target for melatonin actions 11, 12. In the present study, we hypothesized that melatonin might be able to attenuate I/R-induced mitochondrial dysfunction in skeletal muscle. Mitochondria dysfunction was determined by the depolarization of mitochondrial membrane potential and the release of the proapoptotic protein, cytochrome c, from the mitochondria. The mitochondrial membrane potential was measured by JC-1 assay in the mitochondrial fractions. The concentrations of cytochrome c were determined by cytochrome c immunoassay in both mitochondrial and cytosolic fractions.
Section snippets
Methods
All experimental procedures and care of the animals were approved by the Institutional Animal Care and Use committee. Male Sprague-Dawley rats weighing 400 to 450 g were used. Anesthesia was accomplished using intraperitoneal sodium pentobarbital (50 mg/kg).
Results
The result of mitochondrial membrane potential (Fig. 1): The average uptake of the fluorescent JC-1 dye (FLU ± SEM/mg protein) in the mitochondrial fraction of muscle cells was significantly decreased in I/R-V group (80697 ± 5355/mg protein) compared with sham I/R group (141303 ± 10986/mg protein) with P < 0.001. This 43% reduction of uptake of JC-1 dye in I/R-V group is an indicator of the depolarization of mitochondrial membrane potential. However, the treatment of melatonin (I/R-Mel)
Discussion
Melatonin, released from the pineal gland, is a great ROS scavenger 7, 8. Melatonin has shown the protective effect on I/R injury in many different organs and tissues (such as in the heart, lung, brain, spinal cord, peripheral nerve, kidney, liver, stomach, intestine, random pattern skin flap, hamster cheek pouch microcirculation, and skeletal muscle), in multiple animal species and in both in vivo and in vitro models 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23. Melatonin has higher
References (43)
- et al.
Ischemia/reperfusion-induced necrosis and apoptosis in the cells isolated from rat skeletal muscle
J Orthop Res
(2008) - et al.
Melatonin and N-acetylcysteine have beneficial effects during hepatic ischemia and reperfusion
Life Sci
(2003) - et al.
Mechanism involved in gastric protection of melatonin against oxidant stress by ischemia-reperfusion in rats
Life Sci
(2001) - et al.
The role of melatonin in prevention of intestinal ischemia-reperfusion injury in rats
J Pediatr Surg
(2000) - et al.
Melatonin attenuates posttransplant lung ischemia-reperfusion injury
Ann Thorac Surg
(2002) - et al.
Cyclosporine A prevents apoptosis-related mitochondrial dysfunction after neonatal cardioplegic arrest
J Thorac Cardiovasc Surg
(2008) - et al.
Melatonin reduces I/R-induced superoxide generation in arterial wall and cell death in skeletal muscle
J Pineal Res
(2006) - et al.
The calcimimetic R-568 induces apoptotic cell death in prostate cancer cells
J Exp Clin Cancer Res
(2009) - et al.
Melatonin protection against lethal myocyte injury induced by doxorubicin as reflected by effects on mitochondrial membrane potential
J Mol Cell Cardiol
(2002) - et al.
Cytochrome c deficiency causes embryonic lethality and attenuates stress-induced apoptosis
Cell
(2000)