Researchers in London, Canada identify new source of appetite stimulant
The extra fat we carry around our middle could be making us hungrier, so we eat more, which in turn leads to even more belly fat. Dr. Kaiping Yang and his colleagues at the Lawson Health Research Institute affiliated with The University of Western Ontario found abdominal fat tissue can produce a hormone that stimulates fat cell production. The researchers hope this discovery will change in the way we think about and treat abdominal obesity.
Yang identified that the hormone Neuropeptide Y (NPY) is produced by abdominal fat tissue. Previously, it was believed to only be produced by the brain. Yang believes this novel finding may lead to new therapeutic targets for combating obesity. Their findings were reported in a recent issue of The FASEB Journal.
The traditional view is that one of the main reasons why overweight people eat more food is because their brains produce the hormone NPY in excessive amounts. NPY is the most potent appetite stimulating hormone known, sending signals to the individual that they are constantly hungry. However, Yang, a Professor in the Departments of Obstetrics & Gynaecology and Physiology & Pharmacology at the Schulich School of Medicine & Dentistry at The University of Western Ontario, has provided evidence that in obese rat models NPY is also produced locally by abdominal fat.
A fat cell cannot replicate itself. But the researchers found NPY increases fat cell number by stimulating the replication of fat cell precursor cells, which then change into fat cells.
Yang says “this may lead to a vicious cycle where NPY produced in the brain causes you to eat more and therefore gain more fat around your middle, and then that fat produces more NYP hormone which leads to even more fat cells.”
Being overweight, regardless of where the fat is located, is unhealthy. However, because of its anatomical location and its byproducts, abdominal fat or the apple-shape is known to be the most dangerous. People predisposed to the apple shape are at an elevated risk for heart disease, Type 2 diabetes, hypertension and some cancers.
Next, the researchers will be investigating whether NPY produced by fat is released into the body’s circulatory system. “We want to know if NPY could potentially be transported in the blood to the brain where it in turn has an impact on the brain to stimulate feelings of hunger,” says Yang. If the researchers find that NPY is in fact transported in the blood circulation then it may be possible to develop a simple blood test to detect increased levels of NPY. “If you can detect NPY early and identify those at risk for abdominal obesity we can then target therapy to turn off NPY. It would be much easier to use drugs to prevent obesity than to treat the diseases caused by obesity.”
In a definitive critical review, scientists at Children’s Hospital & Research Center Oakland ask whether there is convincing biological or behavioral evidence linking vitamin D deficiency to brain dysfunction. Joyce C. McCann, Ph.D., assistant staff scientist and Bruce N. Ames, Ph.D., senior scientist at Children’s Hospital Oakland Research Institute (CHORI) conclude that there is ample biological evidence to suggest an important role for vitamin D in brain development and function, and that supplementation for groups chronically low in vitamin D is warranted. Their conclusions will be published on April 22, 2008 in the Federation of American Societies for Experimental Biology (FASEB) Journal.
“This critical analysis of vitamin D function and the brain is a model of careful thinking about nutrition and behavior”, says Gerald Weissmann, MD, Editor-in-Chief of the FASEB Journal “One wishes that all studies of nutritional supplements or requirements were this thoughtful. Drs. McCann and Ames deftly show that while vitamin D has an important role in the development and function of the brain, its exact effects on behavior remain unclear. Pointing to the need for further study, the authors argue for vitamin D supplementation in groups at risk.”
Vitamin D has long been known to promote healthy bones by regulating calcium levels in the body. Lack of sufficient vitamin D in very young children results in rickets, which can be easily prevented by vitamin D supplements. Only recently the scientific community has become aware of a much broader role for vitamin D. For example, we now know that, in addition to its role in maintaining bone health, vitamin D is involved in differentiation of tissues during development and in proper functioning of the immune system. In fact, over 900 different genes are now known to be able to bind the vitamin D receptor, through which vitamin D mediates its effects. In addition to protecting against rickets, evidence now strongly indicates that a plentiful supply of vitamin D helps to protect against bone fractures in the elderly. Evidence also continues to accumulate suggesting a beneficial role for vitamin D in protecting against autoimmune diseases, including multiple sclerosis and type I diabetes, as well as some forms of cancer, particularly colorectal and breast.
Vit D Brain