Washington: We begin to lose muscle by the age of 40. By 80, up to a third of it may be gone. It`s an inevitable process of ageing called sarcopenia. But why does it happen and can it be stopped? A new study has provided some answers.
The study, conducted in mice with accelerated muscle loss at The University of Texas Health Science Centre (UTHSC), San Antonio, found less protection from antioxidants and more damage from oxidative stress results in impairment to cells` energy centres (powerhouses) called mitochondria, which slowly leads to death of muscle cells.
Your body constantly reacts with oxygen as you breathe and your cells produce energy. As a consequence of this activity, highly reactive molecules are produced known as free radicals.
Free radicals interact with other molecules within cells. This can cause oxidative damage to proteins, membranes and genes.
Oxidative damage has been implicated in cancer and Alzheimer`s and has an impact on the body`s aging process.
A team directed by Holly Van Remmen, UTHSC associate professor in cellular and structural biology, found that without a certain antioxidant enzyme to balance the formation of harmful reactive oxygen species (ROS), mitochondria fail to work properly.
The mitochondria even add to the spate of ROS molecules and release factors leading to cell death.
"The impaired function of mitochondria also has a detrimental effect on the way motor neurons `talk` to the muscle to achieve muscle contraction," Van Remmen said.
Youngmok C Jang, study co-author, probed mice genetically engineered to lack an antioxidant enzyme called copper-zinc superoxide dismutase.
He compared mitochondria from these mice and normal mice and found reduced function of the energy centres in the enzyme-deficient mice.
This contributed to more cell death and muscle atrophy in the rodents. "As a result, their muscles were a lot smaller and weaker," Van Remmen said, according to an UTHSC release.
If a muscle-preserving therapy is one day developed, future generations of young men will be able to keep their muscle shirts a bit longer.