Low Levels of Brain Chemical May Lead to Obesity, NIH Study of Rare Disorder Shows

As I chew furiously on my DHA added fish oil chews, and take my anti-seizure medication, I give you this:

"A brain chemical that plays a role in long term memory also appears to be involved in regulating how much people eat and their likelihood of becoming obese, according to a National Institutes of Health study of a rare genetic condition."

http://www.nichd.nih.gov/news/releases/aug272008_BDNF.cfm

The full article is below.

            

Brain derived neurotrophic factor (BDNF) is, as its name implies,               produced in the brain. Studies of laboratory animals have suggested               it also helps control appetite and weight. The NIH study, appearing               in the August 28 New England Journal of Medicine, provides the               first strong evidence that BDNF is important for body weight in               human beings as well.

            

The NIH researchers studied children and adults with WAGR syndrome,               a rare genetic condition. The researchers found that some of the               people with this syndrome lack a gene for BDNF and have correspondingly               low blood levels of the substance. The people in this subgroup               also have unusually large appetites and a strong tendency towards               obesity.

            

“This is a promising new lead in the search for biological pathways               that contribute to obesity,” said Duane Alexander, M.D., director               of the NIH’s Eunice Kennedy Shriver National Institute of Child               Health and Human Development.  “This finding may eventually lead               to the development of new drugs to regulate appetite in people               who have not had success with other treatments.”

            

The study’s first author was Joan C. Han, M.D. and the senior               author was Jack A. Yanovski, M.D., Ph.D., both of NICHD’s Unit               on Growth and Obesity. Other authors of the study were from the               National Human Genome Research Institute and the National Institute               on Drug Abuse, also part of the NIH. Funding for the study was               provided by the NICHD and the NIH Office of Rare Diseases.

            

WAGR syndrome is an acronym for the complex of symptoms seen in               people who have the condition. These include Wilms tumor, a tumor               of the kidneys; aniridia, absence of the iris, in the eye; genital               and urinary tract abnormalities; and mental retardation. WAGR syndrome               occurs in one out of every 500,000 to 1 million persons.

            

People with WAGR syndrome lack genes that are grouped on chromosome               11. All people with WAGR syndrome lack two specific genes, called               WT1 and PAX6, but each person can also be missing other nearby               genes. For the most part, human chromosomes are arranged in pairs,               and the genetic deletions found in WAGR syndrome occur on only               one of the two copies of chromosome 11.

            

WT1 and PAX6 are located in the region of the chromosome that’s               near the gene for BDNF. For this reason, the NIH researchers examined               chromosome 11 from WAGR syndrome patients to learn if the gene               for BDNF was affected, explained Dr. Yanovski.

            

Studies of mice had determined that animals missing a working               copy of the BDNF gene were prone to excessive eating and obesity.               Studies in human beings, however, hadn’t proved that BDNF was important               in people.

            

In the current study, the NIH researchers conducted analyses of               chromosome 11 in 33 patients with WAGR syndrome. A total of 19               patients (58 percent) had deletions of all or a major proportion               of one copy of the gene for BDNF. By age 10, all of the 19 were               obese and were reported to have a strong tendency to overeat. Moreover,               all of the 19 had blood levels of BDNF that were roughly 50 percent               lower than those of patients who had two working copies of the               BDNF gene. The patients who had two working copies of the BDNF               gene were no more likely to develop childhood onset obesity than               the general population, and did not report unusually high levels               of overeating.

            

Dr. Yanovski explained that BDNF is believed to work in combination               with a variety of other substances that regulate appetite and body               weight. Chief among these is leptin, a hormone found to be involved               in signaling hunger. Dr. Yanovski added that release of BDNF in               the hypothalamus, a part of the brain involved in controlling eating,               is believed to be indirectly triggered by leptin. Studies of the               relationship between the two, and of BDNF’s action on tissues,               may lead to the development of new drugs to treat obesity in some               individuals.

            

The NICHD sponsors research on development, before and after birth;               maternal, child, and family health; reproductive biology and population               issues; and medical rehabilitation. For more information, visit               the Institute’s Web site at http://www.nichd.nih.gov/.

            The National Institutes of Health (NIH) — The Nation's             Medical Research Agency — includes 27 Institutes and Centers             and is a component of the U.S. Department of Health and Human Services.             It is the primary federal agency for conducting and supporting basic,             clinical and translational medical research, and it investigates             the causes, treatments, and cures for both common and rare diseases.             For more information about NIH and its programs, visit www.nih.gov.