How leptin prevents obesity

Washington, July 14 (ANI): That the hormone leptin works in the brain to prevent obesity has been known for quite some time.

But how it does so has always remained a mystery.

Now, a new research has revealed the neurobiological mechanisms that may underlie the antiobesity effects of leptin.

"Leptin is a hormone that is secreted by fat cells and acts at its receptor in the brain to decrease food intake and promote energy expenditure," explains senior study author Dr. Bradford B. Lowell from Beth Israel Deaconess Medical Center and Harvard Medical School.

"However, despite intensive investigation, the underlying mechanisms responsible for this are poorly understood, in part due to incomplete knowledge regarding leptin-responsive neurons."

Previous studies by Dr. Lowell's group and others pinpointed a region of the brain as the site of key components related to the control of obesity.

In particular, pro-opiomelanocortin (POMC) neurons, which have been shown to play a key role in appetite suppression, reside in this region.

Although many POMC neurons express receptors for leptin, direct action of leptin on POMC neurons has not been shown to play a large role in controlling body weight.

This suggests that there are likely to be other leptin-responsive neurons that are critical for leptin's antiobesity actions.

In the current study, Dr. Lowell and colleagues took a new approach for identifying these "unidentified" body weight-regulating neurons and investigated whether leptin's effects are mediated primarily by excitatory (glutamate) or inhibitory (GABA) neurons.

Their research showed that GABA, or glutamate neurons, predominately mediate the antiobesity effects of leptin. They found that these GABA neurons work with POMC neurons to facilitate antiobesity effects.

Their study concluded that the indirect regulation of POMC neurons by leptin in the brain, reconcile the critical role POMC neurons have in regulating body weight and directing action of leptin.

The study was recently published in the journal Neuron. (ANI)