Insulin in the Brain: Recent Advances on its Source and Target - A Review

Insulin is not just a peripheral hormone but it's present in the brain and has its receptors distributed unevenly throughout the brain. It crosses the Blood Brain Barrier-BBB through a saturable transport mechanism. It has independent functions in the periphery and brain & leads parallel lives. It's basically a metabolic regulatory hormone in the periphery but affects feeding, cognition amongst others in the brain. Host of its cerebral functions in the brain is mediated through the Phosphoinositide-3-kinase P1(3)K and Ras/Mitogen activated protein kinase (MAPK) cascades. An impairment in these signal transductions is mostly evident as Alzheimer's disease and obesity. A neuron-based insulin therapy is being proposed as a replacement to insulin beta cells in the pancreas.

Key Words: Insulin, pancreas, Alzheimer's disease