Neurotransmitter receptor distribution and
epilepsy
Hippocampal sclerosis is a thickening and
hardening of the brain tissue in the hippocampus.
It is a very common feature of TLE. This
sort of epilepsy is frequently not treatable
with AEDs, but responds well to surgery.
Dr Nicholas Barnes of the University
of Birmingham has been awarded £45,316
over two years to look at brain tissue from
patients who have had surgery for TLE caused
by hippocampal sclerosis. These patients
appear to have a different distribution
of some types of neurotransmitter receptors
in the part of the brain where the seizures
occur.
Neurotransmitters are molecules which carry
information from one neurone to the next.
They fall into two broad classes: inhibitory,
which slow down neurone activity, and excitatory,
which speed it up. Each type of neurotransmitter
has its own receptor, and some have more
than one type of receptor. Receptors are
protein complexes in the wall of a neurone.
The speed at which a message can be transmitted
through the brain depends both on the number
of neurotransmitter molecules and also on
the number of receptors. (Think of the neurotransmitters
as letters and the receptors as dedicated
postboxes, each only taking a specific size
of letter or parcel. Whether your correspondent
gets your message depends both on the number
of letters you write and also on the number
of postboxes you can find for them.) This
has implications for epilepsy as a seizure
happens when far too many messages are sent,
swamping the brain's circuits. Too many
excitatory neurotransmitters released or
too many of their receptors available can
make this happen more easily.
Dr Barnes, in his project entitled "Neurotransmitter
receptor distribution in patients with TLE
due to hippocampal sclerosis",
will try to quantify exactly which types
of brain cell contain the receptors and
how and why (on a molecular and cellular
level) the distribution of receptors changes.
The hope is that it will then be possible
to develop new AEDs which target these receptors.
