Pathological aspects of brain transport phenomena

Area of Science:

• Neuroscience
• Physiology
• Biochemistry

Background:

• The blood-brain barrier (BBB) tightly regulates the transport of substances into the brain.
• Pathological conditions can compromise BBB integrity and alter nutrient transport.
• Understanding these alterations is key to addressing neurological disorders.

Purpose of the Study:

• To review and discuss investigations on cerebral transport phenomena in pathological conditions.
• To examine the effects of BBB injury and altered physiological states on nutrient transport.
• To analyze transport mechanisms in synaptosomes and cerebral capillaries.

Main Methods:

• Experimental induction of BBB injury using HgCl2 or hyperosmolar perfusates.
• Assessment of transport under conditions of ischemia, hypoxia, and altered pCO2.
• Measurement of brain uptake of glucose analogues, amino acids, and protein tracers.
• Analysis of synaptosome and cerebral capillary function.

Main Results:

• BBB injury increased protein permeability; glucose analogue uptake decreased with HgCl2 but increased with hyperosmolar perfusates.
• Ischemia led to increased vesicular transport and altered glucose analogue passage across the BBB, dependent on duration.
• 2-deoxy-D-glucose uptake in synaptosomes recovered after ischemia.
• Hypoxia and hypercapnia decreased nutrient uptake, while hypocapnia showed varied effects.
• Cerebral glucose uptake may be linked to capillary function.

Conclusions:

• Cerebral transport is sensitive to BBB injury and changes in oxygen and CO2 levels.
• Ischemia reversibly affects glucose transport mechanisms.
• BBB permeability and nutrient transport are complexly regulated in pathological states.
• Further research into cerebral capillary function is warranted.