May 17, 2013
Anti-Appetite Hormone In Brain Affected Negatively By Obesity
Michael Harper for redOrbit.com — Your Universe Online
Obesity has been found to alter the body in more ways than one. Previous studies have shown that adding too much mass to a body can chemically and genetically alter the body, sending into a sort of downward spiral which can be hard to steer out of.
Last month, a Baylor College of Medicine study showed that mice, when overfed as babies, are genetically more inclined to become overweight adults. Now a study from Brown University has found that obesity can hinder the production of an appetite-curbing hormone in rats, creating a self-sustaining obesity that may be difficult to overcome.
Senior author Eduardo A. Nillni, professor of medicine at Brown University and a researcher at Rhode Island Hospital led the research and claims this is the first time any study has ever looked at this specific hormonal break down in the brain. His study is now published in the Journal of Biological Chemistry.
It had been observed before that obesity creates a sort of resistance to leptin, a hormone which alerts the brain to the amount of fat in the body. Nillni had even previously observed this resistance when he noticed that obese rats had a low volume of another hormone which performs some of the same functions.
Alpha-MSH not only tells the brain to stop seeking food, it also triggers the thyroid gland to start burning extra calories in the body. With alpha-MSH running low in the brain, obese rats were more likely to remain obese through their lives even if they had plenty of the leptin hormone.
This caused Nillni and his colleagues to look for other reasons for the rats´ stubborn obesity. The result was a study which tried to identify where the alpha-MSH deficit originated. The team began by splitting a herd of rats into two groups. The first group was fed a high-calorie diet for 12 weeks; the second group was fed a normal diet. Once the 12 weeks were over, the researchers studied the hormone levels and brain cells of these rats and found that those who developed a “diet-induced obesity” were less able to handle a certain kind of protein in the brain.
The endoplasmic reticulum (ER) is a mechanism in the brain responsible for creating protein. When it becomes stressed or overworked, it can be difficult for the brain to process hormones responsible for burning calories and suppressing appetite. Due to an overwhelmed ER, the obese rats had a significantly more difficult time handling these hormones, such as alpha-MSH than other healthy rats.
Nillni and his fellow researchers decided to experiment with this mechanism even further, attempting to lighten the stress on the ER to see if it would create more alpha-MSH in the brain. After treating the obese rats with a chemical known to reduce ER stress, they saw an increase in alpha-MSH production. In other words, this appetite-curbing protein could be recreated with a little medicinal help.
“This is so novel. Nobody ever looked at that,” said Nillni in a statement.
It´s a development which Nillni and his colleagues believe could help future researchers treat the vicious cycle of obesity. Nillni does warn, however, that though his team was able to create more alpha-MSH hormones by use of medication, the kinds of drugs needed to kickstart this hormone production are not yet available to treat obesity in humans.
As it stands, there could be dangerous side effects from the drug. Furthermore, the specific drug used in this rat test has not yet been approved by the FDA.