Biochem- Neurochemical Messengers Flashcards
What are the 3 catacholamines?
Dopamine (DA), Norepinephrine (NE) and Epinephrine (E)
Which amino acid are the catecholamines derived from?
Tyrosine
Where do you get tyrosine for the synthesis of the catecholamines?
The liveer or diet
Which enzyme is the RLS and converts L-Tyr to L-DOPA?
Tyrosine hydroxylase
What are the 2 substrates that tyrosine hydroxylase needs for the conversion of Try –>l-dopa?
BH4 and O2
Which enzyme converts L-dopa –> DA?
Dopa decarboxylase
Where is DA synthesized in the presynaptic terminal?
The cytosol
Once DA gets inside presynaptic vesicles, what 2 things can happen?
- It can wait to be released if the neuron is dopaminergic, or 2. be converted to NE if the neuron is adrenergic.
Which enzyme and substrates convert DA –> NE?
dβh
If the cell is going to release E, what is the enzyme to convert NE –> E?
PMNT (1 letter away from being the most badass cartoon in the history of all cartoons. I used to call myself Danieltello and my friend growing up was Michaelangelo. CHAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA)
PMNT requires an important substrate for methylation of NE to make E. Which one is that?
SAM
The synthesis of SAM requires what 2 important substrates?
Folate and B12
So the administration of SAM can treat what type of disorder? Why?
Depression, becuase NT’s need it to methylate precursors like NE, which are depressed in the brain.
What is the name of the transporter that takes up DA into storage vesicles?
VMAT2
VMAT2 uses what type of energy system to get DA into the cells?
Secondary active transport by having protons pumped into the vesicles by vesicular ATPase and then they can exchange for a positively charged catecholamine to get in the vesicle.
In the vesicle, what other 2 things are the DA molecules complexed with?
ATP and chromogranins
Which drug can inhibit the VMAT2 channel and block the DA storage?
Reserpine
Schizophrenia has what type of change in D2 receptors?
Excessive activation
Street heroin (MPTP) can be metabolized by what enzyme to induce oxidative damage to the neurons?
MAO-B
What is tyramine?
Tyramine is a degredation product of Tyr and can lead to headaches, palpitations, nausea and vomiting because it mimics NE and binds to their receptors.
What happens to tyramine levels if someone is taking an MAOi?
It’s normally inactivated by MAO-A so it will increase if someone is taking an MAOi
D1/D5- Excitatory or inhibitory?
Excitatory
D1/D5- Metabotropic or ionotropic?
Gs pathway
D2/D3/D4- Excitatory or inhibitory?
Inhibitory
D2/D3/D4- Metabotropic or ionotropic?
Gi pathway
α1 – excitatory or inhbitory?
Excitatory
α1 – metabotropic or ionotropic?
Gq pathway
α2 – excitatory or inhibitory?
inhibitory
α2 – metabotropic or ionotropic?
Gi pathway
β1, β2, β3– excitatory or inhibitory?
Excitatory
β1, β2, β3– metabotropic or ionotropic?
Gs pathway
What is the general role of MAO’s?
inactivates catecholamines are are not protected in the vesicles.
Which 2 NT’s does MAO-A’s degrade?
NE and serotonin
Which NT’s does MAO-B degrade?
degrades a wide spectrum of phenylethylamines.
What does COMT do?
transfers a methyl group from SAM to a hydroxyl group on the catecholamine
Which 2 vitamins is COMT dependent on indirectly?
Dependent on B12 and folate indirectly b/c of SAM.
HVA in the urine and blood is a marker for the turnover or what catecholamine?
DA
VMA in the urine and blood is a marker for the turnover of which catecholamines?
NE and E
What are the 2 indolamines?
Serotonin and melatonin
Which AA is serotonin and melatonin made from?
Tryptophan
What is the enzyme that uses BH4 and O2 to convert Trp –> 5-hydroxy Trp?
Trp hydroxylase
What is the enzyme that converts 5-OH Trp to serotonin?
Dopa decarboxylase