Melting Body Fat: Is it In Your Head?
Muscles may not be the only organ that burns body fat. A recent study published in Cell showed that directly stimulating neurons in adipose (fat) tissue may induce breakdown, providing insight on novel therapies to combat obesity.
Scientists first identified leptin, a hormone produced by fat cells that acts as an “adipostat”, 20 years ago. Low fat stores tend to correspond with low levels of the hormone, which increases appetite and lowers basal metabolism. High fat stores are often associated with elevated levels of leptin, which suppress appetite and increase fat breakdown. However until recently, scientists were unclear on how leptin action in the brain signaled back to the fat tissue.
To investigate how leptin mediates lipolysis (i.e. breakdown of adipose tissue) , Ana Domingos at Instituto Gulbenkian de Ciencia in Portugal and colleagues used intravital two-photon microscopy to show that sympathetic nerve fibers established neuro-adipose junctions in the adipocytes of living mice. Additionally, local optogenetic stimulation of the sympathetic inputs induced lipolysis and reduced white adipose tissue mass in mice. According to the authors, this local activation of the neurons induced release of the neurotransmitter norepinephrine, which triggered a cascade of signaling events leading to lipolysis. Domingos indicates these findings will be important for therapies targeted at treating central leptin resistance, a condition commonly present in obese individuals that makes them insensitive to the effects of leptin.
Read more: Zeng W, et al (2015). Sympathetic Neuro-adipose Connections Mediate Leptin-Driven Lipolysis. Cell; 163(1):84.