What tells capillaries to increase?
Astrocyte signals leads to breakdown of phospholipids –> arachidonic acid (AA) which can make prostaglandins like HETE (constriction) and EETs (dilation)
-Low O2 promotes vasodilation
What is the significance of the Astrocyte-Neuron Lactate Shuttle (ANLS)?
Shuttles glucose –> lactate to the brain.
- If this shuttle is defective, you won’t know until child stops breast feeding and gets off ketone diet. Then child will not get enough glucose to the brain
- Hypoglycorrhachia = low glucose in CSF
What is used when glucose in unavailable? Why would glucose be unavailable to the brain?
KETONES (D-3-hydroxybutyrate & Acetoacetate)
- Used in extreme starvation & fasting, Hibernation, Neonates, Suckling (mother’s milk = mostly fat)
- These are a good alternative to glucose bc it requires less oxygen (28% less) to make ATP
What is a risk factor for AD?
Leaky blood vessels. They allow more things to cross the BBB, which exposes brain to toxic chemicals and leads to cognitive degeneration.
What area of the brain is affected by AD a lot? What about it?
Hippocampus (memory)
- Barrier permeability in hippocampus increases with aging but not so much in other regions
- In AD increased permeability in hippocampus is much more severe than just aging!
What are the different proteins associated with tight junctions? What do these junctions do?
- Occludin
- Claudin
- JAM (juncitonal adhesion molecule)
- Helps from BBB - makes up contact/blocking between two cells
What substances can get into the brain from the blood?
Lipophilic substances like alcohol, ethanol (also cocaine, THD <– all lipid soluble)
What is the significance of MCT-1?
Monocarboxylate Transporter - 1
-Transport protein that movement lactic acid from in to out
[lactic acid, acetate, butyrate, Ketones (D-beta-hydrocybutyrate & Acetoacetate)
-This transporter is located right on the brain capillaries!
