Central nervous system insulin signaling can influence the rate of insulin influx into brain.
Level 5 - mechanism / opinion, no new human data
Preclinical animal research (mice)
PubMed 37076875 · doi:10.1186/s12987-023-00431-6
What was done
Researchers tested whether manipulating central nervous system (CNS) insulin levels or activity affects the blood-to-brain transport of radioactively labeled insulin across the blood-brain barrier (BBB) in young, healthy mice. Interventions included direct brain injection of insulin, intranasal insulin administration, and pharmacological blockade of the central insulin receptor in male and female mice.
What was found
The abstract provides directional findings without quantitative metrics or effect sizes. Direct central insulin injection decreased whole-brain and olfactory bulb insulin transport across the BBB in male mice. In female mice, central insulin receptor blockade decreased insulin transport to the whole brain and hypothalamus. Intranasal insulin administration reduced insulin transport across the BBB specifically in the hypothalamus.
Why it matters
This study provides evidence of a central feedback loop where CNS insulin signaling modulates its own influx across the BBB. This mechanism may help explain why central insulin resistance is associated with impaired insulin uptake in neurodegenerative conditions such as Alzheimer's disease.
Limits
The study was conducted in healthy young mice rather than humans or disease models. The abstract omits sample sizes, specific drug dosages, and numerical data (percentages, transport rates, and variance metrics). Distinct sex- and region-specific discrepancies were noted across interventions but not mechanistically resolved in the abstract.
Cited by
- supports When the brain develops insulin resistance, insulin has a harder time crossing into the brain.