New research from scientists at Beth Israel Deaconess Medical Center has uncovered a role for the neurotransmitter GABA in maintaining body weight, energy balance and appetite.
Influencing body weight is a complex process, as any dieter can tell you. As science continues to investigate the brain’s intricate circuitry and its part in metabolism, we are forming a clearer concept of the multiple phenomena that lead to weight gain or weight loss.
“Body weight maintenance is made up of three basic stages,”
explains Bradford Lowell, MD, PhD, senior author of the paper, published in the August 10 on-line issue of Nature Neuroscience.
“In the first stage, the brain receives sensory input from the body [including information provided by circulating hormones such as leptin and ghrelin and from fuels such as glucose and fatty acids],” says Lowell.
In the second stage, this sensory information in the brain integrates with cues received from the environment (such as aromas and other enticements), as well as with information about emotional states.
In the third stage, the brain’s neurocircuitry takes over, enabling the brain to make the proper adjustments in food intake and energy expenditure in order to maintain energy balance – and prevent weight gain and obesity.
GABA Weightloss Products
GABA as a supplement can naturally stimulate your body to produce higher levels of Human Growth Hormone (HGH). Indeed, people who are taking GABA have a tendency to lose body fat. Studies have shown that higher levels of HGH are linked to lower levels of body fat and much better fat to lean mass ratios.
GABA , or Gamma Aminobutyric Acid, is an amino acid classified as a neurotransmitter. It is available in supplement form at health food and vitamin stores. Many clinical studies have been done on GABA’s ability to raise growth hormone levels.
AgRP and Metabolism
“It is well known that AgRP [Agouti-related protein] neurons play a critical role in feeding and energy balance regulation. However, the deletion of AgRP and NPY [two neuropeptides released from the AgRP neurons] produces little metabolic effect,"
says Qingchun Tong, PhD, the current study’s first author.
One theory proposed was that release of the GABA neurotransmitter mediates the function of AgRP neurons, an idea that had long been postulated but never examined.
To test this hypothesis, Tong and his colleagues bred a group of mice with disrupted release of GABA specifically from the AgRP neurons. As predicted, the genetically altered mice exhibited profound metabolic changes.
“The mice with AgRP neuron-specific disruption of GABA release were lean, had higher energy expenditure and showed resistance to diet-induced obesity,” said Tong. “We also found that these animals showed reduced food intake response to the hormone ghrelin. This suggests to us that the neurocircuit engaging GABA release from the AgRP neurons mediates at least part of ghrelin’s appetite-stimulating action."
A number of studies examining the function of glutamate and GABA release from other groups of neurons are currently underway as investigators continue to invetigate the brain’s neurocircuitry.
“As these new findings demonstrate, GABA release is an important component that mediates the function of AgRP neurons. Discoveries such as this will ultimately help us to design an efficient strategy to tackle the current epidemic of obesity and metabolic disease,"
Synaptic release of GABA by AgRP neurons is required for normal regulation of energy balance- Qingchun Tong, Chian-Ping Ye, Juli E Jones, Joel K Elmquist & Bradford B Lowell - Nature Neuroscience advance online publication Published online: 10 August 2008 doi:10.1038/nn.2167
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