Navigation Links
Study offers insights into role of muscle weakness in Down syndrome
Date:12/17/2012

BETHESDA, Md. (Dec. 17, 2012)It is well known that people with Down syndrome (DS) suffer from marked muscle weakness. Even the simple tasks of independent living, such as getting out of a chair or climbing a flight of stairs, can become major obstacles. This can reduce the quality of life for those with DS and lead to a loss of independence. Now, a new study sheds light on some of the suspected causes of muscle weakness.

Led by scientists from Syracuse University, a research team has investigated muscle weakness in a mouse model of DS. "If we understand the cause of this muscle weakness, we can begin to look at potential therapies for treating it," said Patrick M. Cowley, lead researcher.

The investigators analyzed the soleus musclea muscle in the lower legand looked into whether the weakness was due to a deficiency of the muscle itself, independent of its activation by the nervous system.

"Surprisingly, we found that the strength of the muscle itself was the same between the DS and control micesuggesting that factors in the nervous system may play a more dominant role in explaining muscle weakness in DS," said Cowley.

The article is entitled "Functional and Biochemical Characterization of the Soleus Muscle in Down Syndrome Mice: Insight into the Muscle Dysfunction Seen in the Human Condition," (http://bit.ly/TXsmby) It appears in the online edition of the American Journal of Physiology Regulatory, Integrative and Comparative Physiology published by the American Physiological Society (APS).

Methodology

The researchers removed soleus muscles from 14 DS mice and 16 controls. They tested the muscles for strength, fatigue and recovery. They also assessed the distribution of fiber types in muscles from both groups.

Because there are three copies instead of two of chromosome 21 in persons with DS, the researchers looked at whether the additional genes caused over-expression of proteins that could then lead to oxidative stress. They also looked for well-known markers of oxidative injury.

A cell-level deficiency in processing of oxygen might also explain the muscle weakness. To determine if this was the case, the researchers tested for the level of two markers for oxidative capacity in the mitochondria, where oxygen metabolism takes place in cells.

Finally, the researchers used microarray analysis to investigate the gene expression and molecular pathways in the muscles of DS mice.

Results

There were no significant differences in the force production of the muscles between the two groups. This finding means that muscle weakness in DS was not due to inherent differences in muscle force generating capacity. Fatigability of the muscle from DS mice was not different from the controls. It did, however, show impaired recovery. There were no significant differences in muscle fiber types between the groups.

While one marker of the cells' ability to process oxygen was lower in DS mice, the other was similar in both groups, meaning that there was not a clear indication of mitochondrial limitation that could explain muscle weakness in DS.

Finally, the researchers found that SOD1, an important antioxidant, was overexpressed in DS mice. This was not a surprise because the gene for SOD1 is tripled in DS. However, there was no increase in markers of oxidative injury, suggesting that this over-expression did not led to oxidative stress in DS muscle.

There were numerous altered pathways in DS muscle revealed by microarray analysis including the breakdown of proteins, metabolism of glucose and fat, and neuromuscular transmission.

Importance of the Findings

This study shows the importance of better understanding muscle weakness in DS. Interestingly, the study found that the weakness was not due to a deficiency in the muscle itself. This may indicate that neural activation of the muscle plays a greater role in explaining weakness in persons with DS. "We now know that the muscle is not the major issue responsible for muscle weakness in DS mice," explained Cowley. "We need to look at the neural factors involvedfrom the motor systems in the brain to the neuromuscular junctionto determine the cause of muscular weakness in people with Down syndrome."


'/>"/>
Contact: Donna Krupa
dkrupa@the-aps.org
American Physiological Society
Source:Eurekalert

Related biology news :

1. Study by UC Santa Barbara researchers suggests that bacteria communicate by touch
2. Law that regulates shark fishery is too liberal: UBC study
3. New study will help protect vulnerable birds from impacts of climate change
4. Study jointly led by UCSB researcher supports theory of extraterrestrial impact
5. BYU study: Using a gun in bear encounters doesnt make you safer
6. 15-year study: When it comes to creating wetlands, Mother Nature is in charge
7. Pycnogenol (French maritime pine bark extract) shown to improve menopause symptoms in new study
8. Crystal structure of archael chromatin clarified in new study
9. EU-funded study underlines importance of Congo Basin for global climate and biodiversity
10. University of Houston study shows BP oil spill hurt marshes, but recovery possible
11. Study demonstrates cells can acquire new functions through transcriptional regulatory network
Post Your Comments:
*Name:
*Comment:
*Email:
(Date:3/29/2016)... LegacyXChange, Inc. (OTC: LEGX ... Protect are pleased to announce our successful effort to ... of writing instruments, ensuring athletes signatures against counterfeiting and ... athletes on LegacyXChange will be assured of ongoing proof ... Bill Bollander , CEO states, "By inserting ...
(Date:3/18/2016)... 2016 --> --> ... Manned & Unmanned Vehicles, Physical infrastructure and Perimeter Surveillance & ... the border security market and the continuing migration crisis in ... Europe has led visiongain to publish this unique ... --> defence & security companies in the border ...
(Date:3/14/2016)... , Allemagne, March 14, 2016 ... ) - --> - Renvoi : image ... --> --> ... biométriques, fournit de nouveaux lecteurs d,empreintes digitales pour ... de DERMALOG sera utilisé pour produire des cartes ...
Breaking Biology News(10 mins):
(Date:4/29/2016)... ... 2016 , ... During a two day program for start-up ... CereScan’s CEO, John Kelley, joined other Denver business leaders in providing business basics ... Denver area business community, shared his top fundamental learnings in building an effective, ...
(Date:4/28/2016)... PUNE, India , April 28, 2016 ... PT, JT, Stirling, and Brayton Cryocoolers), Service (Technical Support, ... Application, and Geography - Global Forecast to 2022", published ... to USD 2.94 Billion by 2022, at a CAGR ... Browse 70 market data Tables and 94 Figures spread ...
(Date:4/28/2016)... York, NY (PRWEB) , ... April 28, 2016 ... ... QuickSTAT has made significant investments in recruiting top industry experts, and expanding its ... Platform, which provides industry-leading tools for clients to manage their clinical trial projects. ...
(Date:4/27/2016)... ... , ... The Pittcon Organizing Committee is pleased to announce that Charles “Chuck” ... of Committee since 1987. Since then, he has served in a number of key ... for both the program and exposition committees. In his professional career, Dr. Gardner is ...
Breaking Biology Technology: