0:00
Hello, I am Dr. Weihong Pan.
In this slide set,
I will discuss "Transport
and Delivery of Neurotrophic Peptides
and Proteins across the BBB".
0:12
Here is the outline.
The first part is about
the blood-brain barrier,
or BBB in short,
to peptides and proteins
with a discussion of flow-independent
influx transport systems.
The second part addresses
influx transport
of neurotrophic peptides and proteins.
The third part
will move to the biotechnology sector
and the goals of CNS drug delivery.
The last part
will focus on physiological regulations,
particularly those related to sleep
and the circadian rhythms.
0:47
In part one,
I will have a brief review
of pertinent features of the BBB,
discuss the dynamic context
involving interstitial space,
cerebrospinal fluid or CSF,
and the cellular compartments.
I will then summarize study methods
including the classics and updates.
1:10
To formulate the image
of a three-dimensional
blood-brain barrier,
let's first take a sample
of 1 square millimeter of brain tissue.
If it is from an
adult human cerebral cortex,
within the 1 square millimeter,
there will be about 50,000 neurons
and 300 million synapses.
No neuron is more than 8 microns away
from a microvessel,
as well as glial cells.
The density of microvessels
is clearly seen
from the vascular corrosion cast image,
in the upper right circle.
Each artery branches to arterioles,
then capillary beds
that has a vast surface area,
and finally,
they drain into venules and small veins.
In the capillaries and the venules
where blood flow is very slow
and conducive to exchange
of fluid components,
that's where the BBB
shows a unique structure
that varies among species.
In general, the microvessel wall
lacks fenestration
and is reinforced by tight junctions
and adherent junction complexes.
This greatly reduces
vascular permeability
and makes specific transport systems
extremely important.
