Neurotransmitter & Drugs 3

Question 1

how are serotonin and melatonin synthesized?

Answer 1

tryptophan is coverted by tryptophan hydroxylase (rate-limiting step) into 5-HTP –> 5-HT –> N-acetyl-5-HT –> melatonin

Question 2

what is the termination of action of serotonin?

Answer 2

reuptake by SERT and repackaging or reuptake and degradation by MAO into 5-HIA and 5-HIAA

Question 3

where is melatonin released from?

Answer 3

the pineal gland

Question 4

where are serotonin cell bodies located?

Answer 4

in the raphe nuclei

Question 5

what are the types of serotonin receptors and what does serotonin regulate?

Answer 5

there are about 10 types of serotonin receptors, 1 is ionotropic (cation channel, 5-HT3) and the other 9 are metabotropic (Gi/o, Gs, or Gq), 5-HT1D is an autoreceptor, it is involved in regulation of sleep, mood disorders, OCD, and hallucinogenic action

Question 6

what are some drugs that act on serotonin?

Answer 6

fluoxetine (prozac) is and SSRI that inhibits SERT which keeps serotonin in synapse and acts as a antidepressant, mescaline (6h), psilocybin (2-4h), and LSD (10-12h) are direct 5-HT agonists

Question 7

what are the effects on MDMA and what causes them?

Answer 7

acts as an indirect monoamine agonist that increases serotonin (causes hallucinogenic effects) and inhibits reuptake of dopamine and norephinephrine and causes more vesicle release (causes stimulant effects and euphoria), also acts as an indirect oxytocin agonist that causes the release of oxytocin (causes social awareness and perception of closeness)

Question 8

what are the negative effects of MDMA?

Answer 8

anxiety, paranoia, insomnia, hyperthermia, bruxism (compulsivity to put things in mouth), flu-like withdrawal, and tolerance

Question 9

how is glutamate synthesized?

Answer 9

glutaminase converts glutamine (a non-essential amino acid) to glutamate (rate-limiting step), glutamate is then converted to GABA

Question 10

what is the termination of action of glutamate?

Answer 10

reuptake by Glu neuron and repackaging, reuptake by astrocytes and back conversion to glutamine, or reuptake by postsynaptic neuron

Question 11

what are the functions of glutamate?

Answer 11

can bind pre or postsynaptically, plasticity of learning and memory, excitotoxicity, Huntington’s and Alzheimer’s disease, seizures

Question 12

what are some drugs that act on glutamine?

Answer 12

ketamine/PCP acts as an indirect NMDAR antagonist, and MSG acts as a direct glutamate agonist

Question 13

what are the three subfamilies of ionotropic glutamate receptors?

Answer 13

NMDA, AMPA, and kainate

Question 14

what are the characteristics of AMPAR and KAR?

Answer 14

allow Na+ in and K+ out, GluA1 AMPAR are also Ca2+ permeable and let Ca2+ in

Question 15

what are the characteristics of NMDAR?

Answer 15

allow Na+, K+, and Ca2+ through the channel, requires glycine and glutamate to bind in order for channel to open, ligand and voltage-gated, slower kinetics

Question 16

how do Mg2+, PCP, and Zn2+ play a role in NMDAR?

Answer 16

Mg2+ blocks channel so a depolarization must occur to repel the Mg2+, PCP can enter the channel and block the flow of ions, Zn2+ can also enter cell after the flow has started to block the channel and act as a negative feedback loop

Question 17

what are the three subfamilies of metabotropic glutamate receptors?

Answer 17

group I, II, or III

Question 18

what are the characteristics of metabotropic glutamate receptors?

Answer 18

can be excitatory or inhibitory depending on G-coupling, blocks Ca2+/Na+, group I is slow and excitatory and group II and III are slow and inhibitory, group II contains glutamate autoreceptors