Blood-brain barrier permeability in senescent rats

Area of Science:

• Neuroscience
• Physiology
• Gerontology

Background:

• The aging central nervous system (CNS) is often associated with changes in the blood-brain barrier (BBB).
• Previous hypotheses suggested a breakdown of the BBB contributes to CNS aging.

Purpose of the Study:

• To investigate the impact of aging on cerebrovascular permeability in Fischer 344 male rats.
• To determine if age-related changes in the BBB are a significant factor in CNS aging.

Main Methods:

• Measurement of 14C-sucrose cerebrovascular permeability in young (3-mo-old) and aged (28-mo-old) rats.
• Intravenous tracer injection, plasma concentration monitoring, and regional brain radioactivity assessment.
• Application of a two-compartment diffusion model to estimate permeability-surface area (PA) and distribution space (Ve).

Main Results:

• Cerebrovascular permeability (PA) was not significantly elevated in aged rats compared to young rats across most brain regions.
• A potential slight increase in PA was observed in white matter of aged rats.
• Cerebral distribution space (Ve) for 14C-sucrose significantly decreased by 45% in aged rats, suggesting reduced extracellular space.

Conclusions:

• The findings do not support the hypothesis that aging of the central nervous system is linked to a breakdown of the blood-brain barrier.
• Reduced extracellular space in the aged brain may be a more significant age-related change than BBB permeability alterations.