Neurotransmitter & Drug 4

Question 1

what are the two ways in which GABA is synthesized?

Answer 1

glucose is converted into GABA by tricarboxylic acid cycle enzymes, glutamine is converted into glutamate by glutaminase, glutamate is then converted by GAD (rate-limiting step) into GABA

Question 2

how does the termination of action of GABA work?

Answer 2

either:
- reuptake by neuron and repackaging
- reuptake by neuron and backconversion by GABA-T into glutamate
- reuptake by astrocyte and backconversion into glutamine then reuptake by the neuron from astrocyte

Question 3

GABA A vs GABA B receptors?

Answer 3

GABA A: ionotropic, pentameric structure, Cl- channel, inhibitory (excitatory in early life)
GABA B: metabotropic, G-protein coupled, By subunit activate K+ channels through shortcut pathway (K+ leaves) or blocks Ca2+ channels

Question 4

what are some drugs that work as indirect GABA A agonists?

Answer 4

barbituates (propofol), benzodiazepines (rhohypnol, xanax), alcohol (also an indirect NMDAR, OR, DA agonist)

Question 5

what are the major depressants that work on GABA?

Answer 5

benzodiazepines, barbiturates, or GHB

Question 6

what are some characteristics of benzodiazepines?

Answer 6

anxiolytic, withdrawal includes anxiety and seizures, act as indirect GABA agonist at the benzodiazepine site, examples are diazepam (valium), alprazolam (xanax), and flunitrazepam (rohypnol)

Question 7

what are some characteristics of barbiturates?

Answer 7

anxiolytic, withdrawal includes anxiety and seizures, act as indirect GABA agonist at the barbiturate site, example is pentobarbital

Question 8

what are some characteristics of GHB?

Answer 8

act as direct GABA B and GHB receptor agonists (stimulates receptor to mimic GABA), example is xyrem to treat catalepsy and narcolepsy