David Kirkpatrick

July 14, 2010

Exercise improves your mental health

Via KurzweilAI.net — regular exercise provides many, many benefits and it’s not surprising improved mental health is among them. Since you’re reading this in front of a computer, take a few minutes sometime today to at least go on a brisk walk. Personally I do a bit of physical exercise, but nothing like I did when I was much younger. Now I completely swear by a 30 minute to hour daily workout on the Wii Fit Plus. For some reason I enjoy the idea of having a virtual trainer guiding my workout. It has something of “the future has arrived” science-fictiony feel to it for me.

Exercise reduces anxiety and depression

Exercise can ameliorate anxiety and depression-like behaviors induced by an adverse early-life environment by altering the chemistry of the hippocampus, the part of the brain that regulates stress responses, researchers from the University of New South Wales (UNSW) have found.

In the study, rats were divided into groups and either isolated from their mothers for controlled periods of time to induce stress or given normal maternal contact. Half were given access to a running wheel. In addition to being more anxious, animals that were subjected to stress early in life had higher levels of stress hormones and fewer steroid receptors in the part of the brain controlling behaviour.

“Both the anxious behaviour and the levels of hormones in these rats were reversed with access to the exercise wheel,” said UNSW Professor of Pharmacology Margaret Morris.

“We know that exercise can elevate mood, but here we are seeing chemical changes that may underpin this improvement. One of these is increases in brain-derived neurotrophic factor (BDNF), which helps nerve cells grow.

“Many neurological diseases appear to have their origins early in life. Stress hormones affect the way nerve cells grow in the brain. This discovery may be giving us a clue about a different way to tackle a range of conditions that affect mood and behaviour,” she said.

More info: University of New South Wales news

Here’s the PhysOrg take on this story.

June 12, 2009

Getting a little gray?

Filed under: et.al., Science — Tags: , , , , , — David Kirkpatrick @ 12:50 am

Maybe it is stress after all.

The release:

Stress makes your hair go gray

Those pesky graying hairs that tend to crop up with age really are signs of stress, reveals a new report in the June 12 issue of Cell, a Cell Press publication.

Researchers have discovered that the kind of “genotoxic stress” that does damage to DNA depletes the melanocyte stem cells (MSCs) within hair follicles that are responsible for making those pigment-producing cells. Rather than dying off, when the going gets tough, those precious stem cells differentiate, forming fully mature melanocytes themselves. Anything that can limit the stress might stop the graying from happening, the researchers said.

“The DNA in cells is under constant attack by exogenously- and endogenously-arising DNA-damaging agents such as mutagenic chemicals, ultraviolet light and ionizing radiation,” said Emi Nishimura of Tokyo Medical and Dental University. “It is estimated that a single cell in mammals can encounter approximately 100,000 DNA damaging events per day.”

Consequently, she explained, cells have elaborate ways to repair damaged DNA and prevent the lesions from being passed on to their daughter cells.

“Once stem cells are damaged irreversibly, the damaged stem cells need to be eliminated to maintain the quality of the stem cell pools,” Nishimura continued. “We found that excessive genotoxic stress triggers differentiation of melanocyte stem cells.” She says that differentiation might be a more sophisticated way to get rid of those cells than stimulating their death.

Nishimura’s group earlier traced the loss of hair color to the gradual dying off of the stem cells that maintain a continuous supply of new melanocytes, giving hair its youthful color. Those specialized stem cells are not only lost, they also turn into fully committed pigment cells and in the wrong place.

Now, they show in mice that irreparable DNA damage, as caused by ionizing radiation, is responsible. They further found that the “caretaker gene” known as ATM (for ataxia telangiectasia mutated) serves as a so-called stemness checkpoint, protecting against MSCs differentiation. That’s why people with Ataxia-telangiectasia, an aging syndrome caused by a mutation in the ATM gene, go gray prematurely.

The findings lend support to the notion that genome instability is a significant factor underlying aging in general, the researchers said. They also support the “stem cell aging hypothesis,” which proposes that DNA damage to long-lived stem cells can be a major cause for the symptoms that come with age. In addition to the aging-associated stem cell depletion typically seen in melanocyte stem cells, qualitative and quantitative changes to other body stem cells have been reported in blood stem cells, cardiac muscle, and skeletal muscle, the researchers said. Stresses on stem cell pools and genome maintenance failures have also been implicated in the decline of tissue renewal capacity and the accelerated appearance of aging-related characteristics.

“In this study, we discovered that hair graying, the most obvious aging phenotype, can be caused by the genomic damage response through stem cell differentiation, which suggests that physiological hair graying can be triggered by the accumulation of unavoidable DNA damage and DNA-damage response associated with aging through MSC differentiation,” they wrote.

 

###

 

The researchers include Ken Inomata, Kanazawa University, Takaramachi, Kanazawa, Ishikawa, Japan, KOSÉ Corporation, Tokyo, Japan, Hokkaido University Graduate School of Medicine; Takahiro Aoto, Kanazawa University, Takaramachi, Kanazawa, Ishikawa, Japan, Tokyo Medical and Dental University, Tokyo, Japan; Nguyen Thanh Binh, Kanazawa University, Takaramachi, Kanazawa, Ishikawa, Japan; Natsuko Okamoto, Kanazawa University, Takaramachi, Kanazawa, Ishikawa, Japan, Kyoto University Graduate School of Medicine, Kyoto, Japan; Shintaro Tanimura, Kanazawa University, Takaramachi, Kanazawa, Ishikawa, Japan, Hokkaido University Graduate School of Medicine; Tomohiko Wakayama, Kanazawa University, Ishikawa, Japan; Shoichi Iseki, Kanazawa University, Ishikawa, Japan; Eiji Hara, The Cancer Institute, Japanese Foundation for Cancer Research, Tokyo, Japan; Takuji Masunaga, KOSÉ Corporation, Tokyo, Japan; Hiroshi Shimizu, Hokkaido University Graduate School of Medicine; and Emi K. Nishimura, Kanazawa University, Takaramachi, Kanazawa, Ishikawa, Japan, Tokyo Medical and Dental University, Tokyo, Japan.

Inomata et al.: “Genotoxic Stress Abrogates Renewal of Melanocyte Stem Cells by Triggering Their Differentiation.” Publishing in Cell 137, 1088-1099, June 12, 2009. DOI 10.1016/j.cell.2009.03.037 www.cell.com.