Figure 1.

In addition to regulating CNS (via neurons and/or astrocytes) functions (such as cognition, depression, and food intake), insulin acts in the brain to regulate peripheral functions via the autonomic nervous system (ANS) and the hypothalamic pituitary axis (HPA). Specifically, insulin acts in the prefrontal cortex and hippocampus to improve cognitive function and reduce depressive symptoms. Insulin acts in the hypothalamic nuclei to decrease food intake and reduce body weight. Via the efferent autonomic nervous system to target organs, insulin acts in the brain to decrease hepatic glucose production, increase lipogenesis, decrease lipolysis, and increase the sympathoadrenal response to hypoglycemia. Insulin acts via the hypothalamic-pituitary-gonadal axis to improve reproductive competence. CNS, central nervous system.