The sympathetic nervous system, not white blood cells, is critically important in the regulation of energy expenditure and thermogenesis, researchers reveal in a new report.
Researchers had previously hypothesized that macrophages, a class of White blood cells, played a major role in thermogenesis, however the new study suggests that the main driver of thermogenesis is the sympathetic nervous system that is chiefly controlled by the brain.
The results were published online in Nature Medicine.
Research team at the Mount Sinai health system focused on Catecholamines, hormones released by the sympathetic nervous system to activate brown fat tissue. Brown adipose tissue is a type of fat tissue that burns energy to produce heat and keep us warm. Catecholamines can also convert white fat tissue, the more familiar kind of fat tissue that stores lipids into a tissue that resembles brown fat. The researchers tested whether macrophages could provide an alternative source of catecholamines, as had been proposed in recent years.
Thermogenesis- a metabolic process is the filed of interest as a target of drugs that allow you to burn energy and hence reduce obesity and improve diabetes. Macrophages are not important as they are unable to make catecholamines, but the brain is clearly important through the sympathetic nervous system.
The ability to generate heat is critical for the survival of warm-blooded animals including human beings as it prevents death by hypothermia. This evolutionary pressure shaped the biology of humans and that of other warm-blooded animals and may explain partly why humans are susceptible to develop diabetes in the environment in which we live.
Lot of effort has been invested in targeting the immune system to cure diabetes and insulin resistance yet there are no anti-inflammatory drugs that have been shown to work well in humans with metabolic disease. This study suggests that perhaps the key to combating the devastating effects of diabetes and obesity in humans is to restore the control of thermogenesis and metabolism by the brain and the autonomic nervous system.