WIKIMEDIA, STEVE BEGERThe hormone leptin operates in hypothalamic neurons to let animals know when they’ve eaten enough. Tamas Horvath, a neurobiologist at Yale School of Medicine, and his colleagues showed in Nature Neuroscience this week (June 1) that glia are also receptive to leptin, and blocking the cells’ leptin receptors alters feeding behaviors in mice.
“Up until now, the scientific community thought that leptin acts exclusively in neurons to modulate behavior and body weight,” Horvath said in a press release. “This work is now changing that paradigm.”
In their study, the authors noted that there were hints that a particular type of glial cell, called an astrocyte, might respond to leptin and take an active part in the leptin signaling that goes on in the hypothalamus. To test this, they knocked out leptin receptors in the astrocytes of adult mice and found that the cells were smaller and formed a greater number of synapses with neurons involved in feeding circuits.
The researchers then injected leptin receptor-knockout mice with the hormone, finding that its normal appetite-blocking effects were diminished. When they administered a hunger hormone, ghrelin, the knockout mice ate more than the control animals did. “These data reveal an active role of glial cells in hypothalamic synaptic remodeling and control of feeding by leptin,” the authors wrote. Whether proper functioning of glia in leptin signaling has a role in obesity still needs to be worked out.