Featured Research

from universities, journals, and other organizations

Drugs To Bulk Up Muscles May Make Injuries More Likely

Date:
January 23, 2008
Source:
University of Michigan Health System
Summary:
Brittle tendons in mice reveal the potential downside of myostatin inhibitor drugs that are attracting interest as possible treatments for muscular dystrophy and as illicit performance-enhancing drugs for athletes. A new animal study raises doubts about one approach to treating muscular dystrophy.

Block the action of a protein that normally regulates muscle mass, and watch your muscles grow. That may sound like a good idea to people with muscle-wasting diseases such as muscular dystrophy, and to older people, whose muscles naturally get smaller and weaker with age. Drugs that restrict the protein myostatin, which normally prevents muscles from being overly bulky, are currently under study, but not on the market, for some medical conditions.

Related Articles


Such drugs, called myostatin inhibitors, also are stirring interest among body builders and athletes. There are already signs of a nascent black market for what might become another illegal performance-enhancing drug in organized sports.

Now, a new University of Michigan study in mice suggests that while myostatin inhibitors may indeed bulk up muscles, they may also bring a troubling side effect -- small, brittle tendons that could make muscle injuries more likely.

"Those interested in myostatin inhibitors need to be aware of the fact that by doing these things to muscles, they may be having negative effects on tendons," says John A. Faulkner, Ph.D., the study's senior author and professor in the Department of Molecular and Integrative Physiology at the U-M Medical School. He is also a research professor at the U-M Institute of Gerontology and professor of biomedical engineering at the U-M College of Engineering.

When you lift weights at the gym, muscle tissue gets damaged. That sets off the release of myostatin, starting a process that clears away damaged proteins and sets the stage for muscle rebuilding, says the study's first author, Christopher L. Mendias, Ph.D. The study suggests we need normal myostatin action for other reasons, too.

"It also appears to make tendons bigger and more flexible," says Mendias, a U-M post-doctoral research fellow in the Regenerative Sciences Training Program in the Department of Surgery at the U-M Medical School.

It is known that blocking myostatin's activity increases muscle mass and strength, but also makes muscle fibers more vulnerable to injury. The U-M team broke new ground by asking if myostatin also affected the make-up and performance of tendons, the fibrous, tough tissues that connect muscle to bone.

Tendons are stiffer than muscles to begin with, and get stiffer with age. If tendons are brittle and short, as they were in myostatin-lacking mice in the study, they can't adequately do their important job of buffering against muscle injuries.

"The tendon acts like a spring," Faulkner says, to reduce some of the force on the muscle in a lengthening contraction. Contraction-induced injury is the most common way we injure our muscles. This type of injury already occurs frequently in people with muscular dystrophy -- so short, brittle tendons could aggravate the problem if myostatin inhibitors turn out to cause the effect in people.

The research team conducted a series of studies using a strain of laboratory mice that lacked the ability to produce myostatin. They tested the mechanical properties of tendons, compared to tendons in a strain of normal laboratory mice. They isolated and treated tendon cells with myostatin and examined what genes control tendon activity. They were able to identify tendon genes that respond to myostatin, which is produced in muscles, showing that myostatin acts as a hormone to promote strong, flexible tendons.

The findings in mice that lack myostatin are very preliminary and will need to be tested in other mouse strains before seeing if they hold true in people, the researchers say. It's also necessary to explore whether tendon brittleness is a problem if myostatin is merely reduced.

In the meantime, the results are intriguing and cautionary for the variety of people interested in the potential of myostatin inhibitors to increase muscle mass.

For people with the most common forms of muscular dystrophy as well as muscle-wasting diseases, myostatin inhibitors represent one potentially effective type of treatment that is being explored. These inhibitors may be able to reverse the loss of muscle mass and also lessen fibrosis, a build-up of connective tissue in muscle that afflicts people with muscular dystrophy and can be a problem in aging and inactivity. One myostatin inhibitor is currently being tested in people as a possible treatment for Duchenne muscular dystrophy, a debilitating disease that affects one in 3,500 boys worldwide.

For certain types of competitive athletes, the possibility that tendons become stiffer with myostatin inhibitors may not seem a disadvantage, says Mendias, who is also an athletic trainer. The prospect of widespread interest in myostatin inhibitors for enhancing performance, which like steroid use is illegal, is very real, he says, adding that the study results point to a greater need for a system to detect their use.

In addition to Faulkner and Mendias, U-M biology student Konstantin I. Bakhurin also authored the study.

Citation: Proceedings of the National Academy of Sciences, Jan. 8 (pp. 388-393, Issue 1, Volume 105)

Funding: The National Institute on Aging and the National institute of Diabetes and Digestive and Kidney Disorders funded the research.


Story Source:

The above story is based on materials provided by University of Michigan Health System. Note: Materials may be edited for content and length.


Cite This Page:

University of Michigan Health System. "Drugs To Bulk Up Muscles May Make Injuries More Likely." ScienceDaily. ScienceDaily, 23 January 2008. <www.sciencedaily.com/releases/2008/01/080122165601.htm>.
University of Michigan Health System. (2008, January 23). Drugs To Bulk Up Muscles May Make Injuries More Likely. ScienceDaily. Retrieved December 19, 2014 from www.sciencedaily.com/releases/2008/01/080122165601.htm
University of Michigan Health System. "Drugs To Bulk Up Muscles May Make Injuries More Likely." ScienceDaily. www.sciencedaily.com/releases/2008/01/080122165601.htm (accessed December 19, 2014).

Share This


More From ScienceDaily



More Health & Medicine News

Friday, December 19, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Kids Die While Under Protective Services

Kids Die While Under Protective Services

AP (Dec. 18, 2014) As part of a six-month investigation of child maltreatment deaths, the AP found that hundreds of deaths from horrific abuse and neglect could have been prevented. AP's Haven Daley reports. (Dec. 18) Video provided by AP
Powered by NewsLook.com
Dads-To-Be Also Experience Hormone Changes During Pregnancy

Dads-To-Be Also Experience Hormone Changes During Pregnancy

Newsy (Dec. 18, 2014) A study from University of Michigan researchers found that expectant fathers see a decrease in testosterone as the baby's birth draws near. Video provided by Newsy
Powered by NewsLook.com
Prenatal Exposure To Pollution Might Increase Autism Risk

Prenatal Exposure To Pollution Might Increase Autism Risk

Newsy (Dec. 18, 2014) Harvard researchers found children whose mothers were exposed to high pollution levels in the third trimester were twice as likely to develop autism. Video provided by Newsy
Powered by NewsLook.com
UN: Up to One Million Facing Hunger in Ebola-Hit Countries

UN: Up to One Million Facing Hunger in Ebola-Hit Countries

AFP (Dec. 17, 2014) Border closures, quarantines and crop losses in West African nations battling the Ebola virus could lead to as many as one million people going hungry, UN food agencies said on Wednesday. Duration: 00:52 Video provided by AFP
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:

Strange & Offbeat Stories


Health & Medicine

Mind & Brain

Living & Well

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins