GABA and glycine Flashcards
gaba is the major transmitter in what area?
the brain.
glycine is the major transmitter in what area?
spinal cord.
what is becucline?
a competitive antagonist of GABA receptors.
what is strychnine?
an antagonist of glycine.
it inhibits glycine receptors.
case study - adulteration:
cocculus indicus multum and picrotoxin was added to beer to make it poorer quality.
picrotoxin causes seizures and respiratory paralysis in the body.
what effect does GABA have in the NS?
inhibitory.
how is GABA synthesised?
Glutamate - carboxyl group —-GAD—-> GABA.
what is GABA synthesised from?
glutamate.
is glutamate inhibitory or excitatory?
excitatory.
is GABA inhibitory or excitatory?
inhibitory.
which enzymes degrades GABA back into glutamate?
GABA-transaminase (GABA-T).
what is GABA-T deficiency called?
encephalopathy.
where is GABAa found?
postsynaptic mem.
where is GABAb found?
postsynaptic and presyn mem.
what type of receptor is GABAa?
ionotropic.
what type of receptor is GABAb?
metabotropic.
what channels is GABAb receptor coupled to?
CA2+ channels
what does activation of Ca2+ channels lead to?
a decrease in ca2+ conductance, resulting in inhibition of transmitter release.
GABAb agonists produce what?
muscle relaxation and antagonists act as anti-epileptics.
what is the main target of alcohol/ethanol?
GABAa and GABAb
what happens when ethanol binds to GABA?
(pharmaodynamics)
excitement, disinhibition, euphoria, relaxation.
what type of disorders do GABA play a role in?
neuropsychiatric disorders.
what effect does GABA have in embryonic NS?
an excitatory effect.
why does GABA have an excitatory effect in embryonic NS?
because of increase cl levels.
case study of strychnine - performance enhancement:
taken to enhance athletic performance as it has convulsive effects.
it disinhibits muscles in the SC, therefore increasing alertness and decreasing fatigue.
what is glycine synthesised from and what enzyme is used?
serine.
SMHT enzyme.
what substances are glycine receptors inhibited by?
strychnine,
non-competitively by picrotoxin,
picrotoxinin.
what effect does glycine have in embryonic NS?
Why?
excitatory,
because of high levels of chlorine intrcellularly.
what type of condition is hereditary hyperplexia?
a glycinerigc condition.
what is hereditary hyperplexia caused by?
a mutation in GLRA1 gene - the mutation creates a receptor that cannot bind to glycine, so glycine is less able to regulate signalling in the SC and brainstem.
