Biochemistry 4.1

Question 1

In regards to neurons, what are GABA and glycine and how do they work?

Answer 1

• inhibitory neurotransmitters

- activate chloride channels

Question 2

In regards to neurons, what is glutamate?

Answer 2

• primary excitatory neurotransmitter of the CNS

- precursor used to make GABA [gamma-amino butyric acid]

Question 3

Which enzyme catalyzes the conversion of glutamate to GABA?

Answer 3

glutamate decarboxylase

Question 4

Where is GABA produced?

Answer 4

presynaptic neuron

Question 5

How does GABA inhibit neurotransmitters?

Answer 5

• activates chloride channels

- hyperpolzrizes post-synaptic membrane due to Cl- influx

Question 6

Where is GABA degraded and how?

Answer 6

GABA transaminase converts to succinate semialdehyde

-presynaptic astrocytes or astrocytes

Question 7

What can GABA be recycled into?

Answer 7

glutamate
glutamine
alpha-ketoglutarate
GABA

Question 8

What is the cofactor for transaminase reactions?

Answer 8

Vitamin B6 (pyrodoxal-5-phsophate)

Question 9

Which prevalent neurotransmitters does the citric acid cycle allow to inter-convert?

Answer 9

oxaloacetate [aspartate] excitatory

alpha-ketoglutarate [glutamate] excitatory

GABA inhibitory

Question 10

What is valproic acid?

Answer 10

anti-epileptic drug

• increase GABA
• decreaze aspartate
• no effect on glutamate

Question 11

Which enzymes does valproic acid (valproate) inhibit?

Answer 11

GABA transaminase

alpha-ketoglutarate dehydrogenase

Question 12

What are benzodiazapines?

Answer 12

first choice treatment for status epilepticus; lorazepam and diazepam
-bind to and increase effect of GABA at GABAa receptor

Question 13

What is phenytoin?

Answer 13

anti seizure therapeutic; binds to and inhibits voltage gated sodium channels