blood brain barrier

1. BLOOD BRAIN
BARRIER-
Characteristics,
function,transport &
similarities between
BBB and blood CSF
barrier
P. MEENALOKSHINI
II MSc Biochemistry

2. Introduction
– Blood brain barrier (BBB)- cerebral endothelium- absent - CVO.
– Limited exchange- passive diffusion.
– Capillaries-carrier mediated and active transport.

4. Characteristics of BBB
– Cerebral capillaries-birth-more permeable. BBB-early life.
– Endothelial cells- tight junction.
– Pores.
– A dense protein matrix.
– Capillaries- astrocytes.

5. Penetration of substances into the
brain
– CO2,O2, H2O-pass easily H+ & HCO3– slowly.
– Plasma proteins, organic molecules-cannot cross. Dyes, substance
bound to protein- can pass.
– Lipid soluble substances-cross more easily than water soluble
substances.
– Glucose- brain metabolism- glucose transporters.
– Ions – pass slowly.
– Bile salts & catechol- do not.

6. – Drugs( sulphonamides and erthromycin )-enter, penicillin&
chloromycetin-limited entry, anti-depressent & psychotropic
drugs-easily enter. Amines-limited entry- L-DOPA & 5-hydroxy
tryptophan – enter rapidly.
– Absence of specific transporter- limited entry.

7. Functions Of BBB
– Maintain constancy of environment-neurons- CNS- homeostatic
mechanism.
– Protection – endogenous and exogenous toxins, prevention-
neurotransmitters.
– Regulated transcellular penetration- H+ & HCO3-.
– Prevents – chemicals, permits-metabolic materials.

8. – O2,CO2,Glucose, aminoacids, electrolytes, drugs, lipid soluble
anesthetic gas-ether,NO-pass.
– Injurious chemical agents, Pathogens- cannot pass.
– Bile pigments- cannot enter,Jaundice-enter-damage basal ganglia-
Kernicterus.

9. – BBB dysfunction-abnormal neuronal activity-seizures.
– Sensor motor neurological dysfunction-reduced metabolic efficacy,
cellular damage.
– Changes in blood flow-key determinant- patho-physiology of brain
injuries.
– BBB.mp4

11. Transport of glucose & aminoacid
glu,aa.mp4
– Endothelial cells- insulin dependent glucose transporter-GLU1-
glycoprotein.
– GLU1-uptake of glucose. Regulation- cell surface GLU1 levels.
– Neuroactive substances-Aspartate & Glutamate-impermeable.
– Limited transport-paracellular barrier.
– Specific solute carriers(SLC)- glucose and aminoacids and other
nutrients.

12. Transport of Ions
– Synaptic and neuronal function-ion channels & transporters.
Water – ion channels.
– Eg- regulated ionic movement-potassium concentration- 2.5 to
2.9mM.
– If increase in conc-change in neuronal activity.
– Neuronal firing & synaptic transmission- influx of ca2+ and Na+ &
eflux of K+, neurotransmitters.

13. Transport of macromolecules
alter[Mute].mp4
– Endocytic vesicles- proteins and peptides.
– Vesicular mechanisms-RMT or AMT- transport diverse large
molecules.
Steps involved in transport
1. Internalization
2. Exocytosis
3. Interaction
Peptide specific transporter-facilitate transport.
Function- signaling cascade.

14. Transport of drugs
drugs.mp4
– Transcranial drug delivery-carrier mediated and receptor mediated
transport- facilitate transport of drugs- CNS pathologies.
– Currently- reengineering of drugs-enables BBB transport.

15. Similarities between BBB & blood
CSF barrier
– Formed –epithelium cells of brain capillaries
– Prevents & blocks -harmful chemicals- toxins- BBB & CSF.
– Substance regulation-substance transport-blood to CSF & BBB.
BBB- oxygen,CO2,glucose & aminoacids.
Chloroid plexus-calcium & endocrine substances.

16. Thank you