Insulin in the brain: there and back again.
Level 5 - mechanism / opinion, no new human data
Narrative review synthesizing mechanistic concepts and associations without primary empirical data.
PubMed 22820012 · doi:10.1016/j.pharmthera.2012.07.006
What was done
Narrative review synthesizing literature on insulin transport across the blood-brain barrier, the roles of brain endothelial cells and pericytes, central insulin signaling via PI3K/Akt and MAPK pathways, and the pathophysiology of central nervous system insulin resistance.
What was found
The abstract reports no quantitative data or statistical estimates. It outlines that insulin crosses the blood-brain barrier via a saturable transporter in brain endothelial cells to affect feeding and cognition independently of peripheral glucose utilization. Hyperglycemia and diabetes alter this transport system and may cause barrier disruption. Central insulin resistance is noted to associate with Alzheimer's disease, depression, and impaired baroreceptor gain during pregnancy.
Why it matters
Synthesizes mechanisms of central insulin action and transport, framing brain insulin resistance as a potential factor in neurodegenerative and neuropsychiatric conditions.
Limits
Narrative review design without primary data, systematic search criteria, or reported sample sizes. Mechanistic descriptions and clinical associations are discussed without quantitative effect estimates.
Cited by
- supports When the brain develops insulin resistance, insulin has a harder time crossing into the brain.