Figure 6.

Schematic diagram demonstrating how various methods of GLP-1 or GLP-1 RA administration into the general circulation can reach and influence brain areas involved in the regulation of energy intake and expenditure [72,73]. (A) Evidence also suggests that GLP-1 receptors in the hepatoportal region [75] (B) and on afferent parasympathetic nerve endings in the intestinal mucosa (C) [76] may generate central nervous system signals influencing insulin secretion and metabolism. Stimulatory signals (+) are shown in green, inhibitory (−) signals are depicted in red, and afferent parasympathetic (vagal) signals are denoted in blue. See the text for a more detailed explanation of the mechanisms.