FIG. 7.

Schematic representation of the role of GLP-1 in the brain as a master switch for the control of glucose fate. 1) Enteric sensors are the first site for glucose detection after an oral glucose load. They send a neural signal to the NTS. 2) Subsequently, the NTS sends a signal toward the hypothalamus, including GLP-1. The enteric signal triggers NPY-positive cells. 3) GLP-1–sensitive cells send a new signal, of unknown origin, toward peripheral tissues, i.e., muscles, to prepare cells to use glucose. 4) The brain would detect glucose. 5) Subsequently, a signal opposite to the one sent by the enteric glucose detector would be sent by the brain to the muscle, as previously described (23). Importantly, the enteric glucose signal is impaired during diabetes.