ScienceDaily (Apr. 2, 2009) — A growth factor used in clinical experiments to rescue dying brain cells in Parkinson patients may cause unwanted weight loss if delivered to specific areas of the brain, according to University of Florida researchers in the March online edition of Molecular Therapy.
The discovery is a cautionary warning for experimental treatments to treat Parkinson's disease that use GDNF, short for glial cell line-derived neurotrophic factor. In addition, the finding broadens understanding of the brain's role in the regulation of metabolism and body weight, suggesting that gene therapy techniques in the brain potentially could control obesity.
In a clinical trial where GDNF was delivered to the fluid-filled spaces of the brain, a common side effect was weight loss beyond what could be attributed to surgery, diet changes and energy expenditure.Based on these results UF researchers looked for areas in the brain that might be responsible for weight loss. The UF researchers noticed that GDNF delivery to the area of the brain known to control weight and general metabolism reduced weight gain in younger rats and caused significant weight loss in older ones.
In the current study, UF scientists compared weight loss in obese rats when two distinct brain targets received therapy using an adeno-associated virus to deliver the GDNF gene.When GDNF flooded a bundle of nerves known as the nigrostriatal tract, a potential target for Parkinson therapy, the obese rats lost a great deal of weight — about 80 grams. But when GDNF protein was overexpressed in a different therapeutic target, the hypothalamus, weight loss was only about half as much. In both locations, there was a steady decrease in body weight throughout the experiment that could only partially be explained by food intake.
The discovery also suggests that direct injections of GDNF therapy to certain brain regions are not advisable because patients could lose unhealthy amounts of weight. Meanwhile, researchers studying potential obesity therapies that work by influencing how the brain regulates energy use and food intake now have much more to consider.
The work was supported by the National Institute of Neurological Disorders and Stroke and by the Medical Research Service of the Department of Veterans Affairs.
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Adapted from materials provided by University of Florida.
reference :
University of Florida (2009, April 2). Experimental Parkinson's Therapy May Have Robust Weight-loss Effect. ScienceDaily. Retrieved April 23, 2009, from http://www.sciencedaily.com /releases/2009/03/090324151949.htm
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