Turning up the Heat on Obesity: Brown adipose tissue (BAT)-induced heat could be a promising therapy to treat obesity and metabolic diseases, according to new research

Released: Wednesday, November 30, 2016

With escalating obesity rates facing our state and nation, there is a need for a deeper understanding of the mechanisms that modulate body weight.

Obesity results when we consume more energy, or calories, than we expend, but underlying mechanisms have many factors.

Brown adipose tissue (BAT), or brown fat, burns calories in order to generate heat and maintain body temperature. Leptin, a hormone produced by fat cells, plays a part in the process of heat generation, also called thermogenesis. It is a crucial and powerful hormone in keeping body weight normal. Past research shows that leptin receptors in specific brain regions regulate the amount of energy expended, body weight and food intake.

Researchers are honing in on how brown adipose tissue can be used to burn fat more effectively.  A team of scientists from LSU's Pennington Biomedical Research Center with colleagues from Tulane University sought to determine the role of leptin receptor expressing neurons in distinct brain areas in energy homeostasis. Previous research discovered brown adipose tissue (BAT)-induced thermogenesis as a promising therapeutic target to treat obesity and metabolic diseases, but scientists do not exactly understand the brain circuits that activate BAT-induced thermogenesis.

"After all these years of obesity research, still we're not able to completely treat the disease because there are so many different circuitries that contribute to obesity. With soaring obesity rates, this research is critical to our understanding of how the energy balance in our bodies is regulated. With a deeper understanding, we can devise better strategies for obesity treatment. Every research endeavor is a proactive step towards a healthier Louisiana," said Dr. Heike Münzberg, associate professor of research at Pennington Biomedical.

Key Findings

Neurons in our brains that express leptin receptors promote weight loss and negative energy balance by suppressing food intake and enhancing energy expenditure. Notably, the preoptic area (POA), which is a region of the brain that controls body temperature, is not considered a site for body weight control and its role in balancing body weight equilibrium is unknown.

These neurons mediate adaptations to ambient temperature changes. In animal models, the activation of these neurons decreased core body temperature and energy expenditure, thus suppressing food intake and causing significant body weight loss.

Most importantly, these neurons regulate food intake and energy expenditure, and are critical for maintaining equilibrium in body weight and body temperature.

Another result was these leptin-receptor preoptic neurons are activated by warm temperatures, but not by cold temperatures.

One result of the study that was inconsistent with earlier models of this circuitry showed other neurons to have no effect on energy expenditure. This study was the first to test the activation of specific neuronal subpopulations at different ambient temperatures in animal models. This research significantly expands our understanding on how the circuits and mechanisms in our brains operate and modulate energy homeostasis, but further investigation is still needed.

This discovery about neural circuits mediated by these neurons has significant implications in better understanding how energy balance is regulated and devising new strategies for obesity treatment. The data suggests a new view into the neurochemical and functional properties of BAT-related preoptic area circuits and highlights their additional role in modulating food intake and body weight. This study contributes to a better understanding of how BAT activity is regulated by the brain and holds great potential as a therapeutic strategy to target obesity.

This type of biomedical research is key to our understanding of chronic diseases such as obesity and it contributes to a body of knowledge that advances the diagnosis, treatment, and prevention of this and other metabolic diseases.

The study entitled Glutamatergic preoptic area neurons that express leptin receptors drive temperature-dependent body weight homeostasis, was recently published in the prestigious Journal of Neuroscience. Read the study here. For more information on research underway at Pennington Biomedical please visit www.pbrc.edu.

For more information on how you can support this and other projects at LSU’s Pennington Biomedical Research Center, visit www.pbrf.org.