Thursday, 2 May 2013

Extending Lifespan by Controlling the Hypothalamus

Researchers at the Albert Einstein College of Medicine at Yeshiva University have discovered a way to extend lifespan and reduce the symptoms of aging in mice. This discovery is very exciting because it may very well apply to humans too. It's also very interesting that one particular part of the body - the hypothalamus in the brain - seems to control aging processes in the rest of the body.

The hypothalamus in the brain:
public domain image from training.seer.cancer.gov
via Wikimedia Commons
The hypothalamus is a small structure inside the brain. It regulates many body processes, including hunger, thirst, water concentration in the body, temperature and sleep. It also controls the activity of the pituitary gland, which is located below the hypothalamus.

The hypothalamus produces antidiuretic hormone and oxytocin, which are sent to the posterior or rear section of the pituitary gland to be released when they're needed. It also produces hormones that stimulate the anterior or front section of the pituitary gland. This section of the pituitary gland secretes at least six hormones of its own. 

Since the hypothalamus is involved in many different processes, it has far-reaching effects inside the body. This may be why controlling the hypothalamus can control aging.

The researchers at Yeshiva University studied a protein complex known as NF-kB. As we age, inflammation in our body increases. NF-kB is involved in the inflammatory process that occurs in the hypothalamus.

When the scientists activated the metabolic pathway involving the NF-kB complex, the aging process sped up in mice. The animals' muscles became weaker and smaller, their skin became thinner, their ability to learn new things decreased and they died sooner. On the other hand, when the scientists blocked the NF-kB pathway, the mice aged more slowly and lived for around twenty percent longer than mice with unaltered pathways.

The discoveries in mice may apply to humans. Photo by Rama, CC BY-SA 2.0 France License
The scientists made another interesting discovery. When they activated the NF-kB pathway, the level of a hypothalamic hormone called GnRH, or gonadotropin-releasing hormone, decreased. This hormone is made by the hypothalamus and stimulates the anterior pituitary to make two hormones that in turn stimulate the reproductive system.

The researchers injected GnRH into the hypothalamus of aging mice. Normally, the brain's ability to make new neurons (nerve cells) decreases as we age. The injected GnRH prevented this problem in mice. In addition, when the mice received daily GnRH injections for a "prolonged period", the rate of cognitive decline that generally occurs with aging slowed significantly.

Processes that occur in mice very often take place in humans too, which is one reason why they are popular animals in research. The discoveries about the relationships between the hypothalamus and aging could be very significant in our future!