DZD scientists at the Institute for Diabetes Research and Metabolic Diseases (IDM) and scientists at the German Center for Neurodegenerative Diseases (DZNE) investigated the effect of aging on insulin concentrations in the periphery and the central nervous system as well as its impact on insulin-dependent brain activity.
In humans, glucose and insulin concentrations in cerebrospinal fluid (CSF) were tightly correlated with the respective serum/plasma concentrations. The CSF/serum ratio for insulin was reduced in older subjects while the CSF/serum ratio for albumin increased with age like for most other proteins. Insulin-mediated cortical brain activity instantly increased in young mice subcutaneously injected with insulin but was significantly reduced and delayed in aged mice during the treatment period. However, when insulin was applied intracerebroventricularly into aged animals, brain activity was readily improved.
An inadequate insulin transport into the central nervous system across the blood-brain barrier may contribute to impaired insulin action in elderly subjects, which finally harms glucose homeostasis and neuronal function. This information is crucial for more efficient preventive and therapeutic interventions like specific insulin sensitizing agents in an aging population.
Sartorius T, Peter A, Heni M, Maetzler W, Fritsche A, Häring HU, Hennige AM. The brain response to peripheral insulin declines with age: a contribution of the blood-brain barrier? doi: 10.1371/journal.pone.0126804. PLoS One. May 12, 2015
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