Week 6

Question 1

What is the Neuronal membrane?

Answer 1

Located on the plasma membrane of neurons, reuptake neurotransmitters from the synaptic cleft back into the presynaptic neuron to terminate signaling and recycle neurotransmitters, use Na⁺ and Cl⁻ gradients to drive the uptake of neurotransmitters against their concentration gradient, function via secondary active transport (co-transport), targets of drugs that affect neurotransmission

Question 2

What is the Vesicular membrane?

Answer 2

found on the membranes of synaptic vesicles inside the presynaptic neuron, load neurotransmitters from the cytoplasm into synaptic vesicles for storage and subsequent release into the synapse, rely on a proton (H⁺) gradient by vesicular ATPase that pumps protons into the vesicle, an antiport mechanism drives neurotransmitter uptake,

Question 3

What are examples of neuronal membrane transporters?

Answer 3

SERT(Serotonin), (DAT)Dopamine, (NET)Norepinephrine, (GLT-1)Glutamate, (GAT)GABA

Question 4

What are examples of vesicular membrane transporters?

Answer 4

VMAT1/VMAT2(monoamines), VGAT(GABA/glycine), VGLUT(glutamate), VAChT(acetylcholine)

Question 5

What is the rate-limiting step of acetylcholine (ACh) synthesis?

Answer 5

• uptake of choline into the presynaptic neuron by choline transporter (ChT)
• can impact both ionotropic and metabotropic receptors
• Choline + Acetyl-CoA → Acetylcholine - done by ChAT enzyme

Question 6

What is the function of AChE?

Answer 6

Breaks down acetylcholine into choline and acetic acid
This happens once ACh is released into the synaptic cleft, ending the signal between neurons

Question 7

Where is AChE located?

Answer 7

Found in the synaptic cleft of neuromuscular junctions & synapses in the CNS

Question 8

What are the catecholamine neurotransmitters?

Answer 8

Dopamine (DA), Norepinephrine (NE), Epinephrine (E),
Tyrosine hydroxylase(TH)

Question 9

What are the steps required for Dopamine synthesis?

Answer 9

movement, reward, and reinforcement learning
synthesized when tyrosine is converted to L-DOPA by tyrosine hydroxylase, then L-DOPA is converted to dopamine by aromatic L-amino acid decarboxylase.

Question 10

What are the steps required for Norepinephrine synthesis?

Answer 10

Sympathetic NS, attention, alertness, wakefulness
Norepinephrine is synthesized when dopamine is converted into norepinephrine by dopamine β-hydroxylase in the presence of oxygen and ascorbic acid.

Question 11

What are the steps required for Epinephrine synthesis?

Answer 11

most of the actions are outside of the brain and used as hormones, secreted into the bloodstream, and act on peripheral tissue
Epinephrine is synthesized when norepinephrine is converted into epinephrine by PNMT using SAM as a methyl donor.

Question 12

What are the steps required for Tyrosine hydroxylase synthesis?

Answer 12

rate-limiting factor in catecholamines, TH is converted into DOPA using AADC into DA to make NE, you have to make DA first - converted from DA using a series of enzymes

Question 13

How does Dopamine get converted into Norepinephrine

Answer 13

inside synaptic vesicles that have a membrane and transporter that brings in DA into the synaptic vesicle, dopamine is made in their cytosol; the presynaptic terminal vesicle has the enzyme DBH inside and converts inside vesicle cytosol

Question 14

What are the main mechanisms for terminating the actions of catecholamines

Answer 14

Metabolism and Reuptake

Question 15

Reuptake defintion?

Answer 15

Reuptake into presynaptic neurons via specific transporters

Question 16

Metabolism degradation definition?

Answer 16

Metabolism degrades catecholamines that are not reabsorbed

Question 17

What are the steps involved in serotonin synthesis?

Answer 17

Amino acid: tryptophan, enzyme converts to intermediary tryptophan hydroxylase
5 - hydroxytryptamine (5-HT)

Question 18

What does PCPA do?

Answer 18

blocks serotonin synthesis, used in research

Question 19

What is serotonin responsible for?

Answer 19

eating, sleeping, arousal, mood, mostly peripheral - 1-2% in the brain, found in the gut

Question 20

What are the main amino acid neurotransmitters?

Answer 20

Glutamate, GABA, Glycine

Question 21

How is GABA synthesized?

Answer 21

Glutamate is the precursor for GABA synthesis, GAD enzyme is responsible for converting glutamate to GABA, and requires pyridoxal phosphate (PLP)

Question 22

What is retrograde signaling?

Answer 22

form of communication in the nervous system where signals are transmitted from the postsynaptic neuron back to the presynaptic neuron

Question 23

What are examples of retrograde messengers?

Answer 23

Endocannabinoids, Nitric Oxide, Carbon monoxide

Question 24

How do Endocannabinoids work as a retrograde messenger?

Answer 24

anandamide endogenous chemicals bind to brain receptor
CB 2: found in peripheral tissue, outside CNS
CB 1: all bind to the same receptors in the brain
dendrite gets excitable: makes endocannabinoids, releases & binds to receptor on presynaptic terminal, binding & activation of CB 1 receptors activates a gene protein, causing voltage-gated calcium channels to close
net outcome: block voltage-gated Ca channels stop neurotransmitter

Question 25

What is endomine's function?

Answer 25

pain and regulation of pain, 2 - AG; comes from neurons

Question 26

How does Nitric Oxide work as a retrograde messenger?

Answer 26

relaxes vessels in brain, involved in learning/memory, pain volume transmission: on demand, no storage, no receptor, bulk transmission: released & go to neuron pass through the membrane internal changes: gene transcription, produced/secreted to bloodstream

Question 27

How does Carbon monoxide work as a retrograde messenger?

Answer 27

relaxes brain blood vessels, regulate gastrointestinal motility

Question 28

What are the endogenous THC-like neurotransmitters?

Answer 28

Anandamide 2-Arachidonoylglycerol

Question 29

What is Anandamide's function

Answer 29

Binds to CB1 and CB2 receptors but has a higher affinity for CB1

Question 30

what is 2-Arachidonoylglycerol's function

Answer 30

Binds to both CB1 and CB2 receptors

Question 31

What is CB1?

Answer 31

located in the brain, responsible for neurotransmitter regulation and psychoactive effects.

Question 32

What is CB2?

Answer 32

Located in immune cells, involved in immune response and inflammation

Question 33

What is the most thoroughly studied transmitter-gated ion channel?

Answer 33

Nicotinic Acetylcholine Receptor: synaptic transmission and ion channels

Question 34

What kind of channel mediates most of the fast synaptic transmission in the CNS?

Answer 34

Ionotropic receptors: ligand-gated ion channels: Glutamate and GABA

Question 35

What are the three glutamate receptor subtypes?

Answer 35

AMPA NMDA Kainate

Question 36

What is AMPA's function?

Answer 36

fast excitatory transmission in the CNS, Na⁺ and K⁺; glutamate binding

Question 37

What is NMDA's function?

Answer 37

synaptic plasticity, learning, and memory, Na⁺, K⁺, and Ca²⁺, Glutamate

Question 38

What is Kainate's function?

Answer 38

synaptic transmission and excitability, Na⁺ and K⁺, glutamate

Question 39

In what important ways do AMPA and NMDA channels differ?

Answer 39

AMPA: mediates excitatory synaptic transmission, NMDA: ligand & depolarization

Question 40

What does a “magnesium block” refer to and what is its importance?

Answer 40

extracellular Mg²⁺ ions block the NMDA receptor at resting membrane potentials

Question 41

Which neurotransmitter mediates most synaptic inhibition in the CNS?

Answer 41

GABA - a main inhibitory neurotransmitter in the brain

Question 42

Which ion passes through when its receptor channel opens?

Answer 42

Metabotropic: Slow Inhibition, Hyperpolarization

Question 43

What types of drugs bind to GABAA receptors and how do they affect its function?

Answer 43

benzodiazepines - enhance the receptor’s function by increasing chloride ion (Cl⁻) influx, leading to hyperpolarization of neurons

Question 44

What is the basic structure of G-protein-coupled receptors?

Answer 44

G-protein-coupled receptors (GPCRs) have a seven-transmembrane alpha-helix structure with an extracellular ligand-binding domain and an intracellular region that interacts with G proteins to trigger signaling pathways.

Question 45

What is the basic mode of operation of guanosine triphosphate (GTP) binding proteins (G-proteins)?

Answer 45

G-proteins activate when GPCRs trigger GDP-GTP exchange, relay signals via the GTP-bound α-subunit, and deactivate when GTP is hydrolyzed to GDP.

Question 46

What are the two types of effector proteins that activated G-proteins exert their effects through?

Answer 46

Activated G-proteins exert their effects through ion channels and enzymes

Question 47

What are the Indolamines?

Answer 47

Serotonin Melatonin

Question 48

What is melatonin's function?

Answer 48

regulation of the sleep-wake cycle, promotes sleepiness, made in the pineal gland Mostly used as a hormone, in the hypothalamus it can also function as a neurotransmitter hormones are released into the bloodstream, not the synaptic gap

Question 49

What are Large molecule neurotransmitters (neuropeptides)

Answer 49

very diverse structures and functions made in the soma and transported in secretory granules away from the active zone of the presynaptic terminal. requires repetitive APs to build up Ca2+ to slowly release ribosomes making precursor peptides that gets converted into neuropeptides and cleaving happens in Golgi, which gets shipped out

Question 50

What are Neuromodulators?

Answer 50

small molecules with characteristics unique from other neurotransmitters

Question 51

What are Autoreceptors?

Answer 51

found on the presynaptic membrane Binds to neurotransmitter that is being released Dampens further release and induce hyperpolarization

Question 52

Precursor example?

Answer 52

L-DOPA (Levodopa) to make dopamine

Question 53

Cause synaptic release example?

Answer 53

Black Widow venom creates pores for Ca2+ in the presynaptic terminal thereby causing neurotransmitter dumping into the synapse

Question 54

Agonist: Activate or enhance post-synaptic receptors example?

Answer 54

Morphine, THC, Nicotine, Ethanol, Benzodiazepines, Barbiturates

Question 55

Inactivate pre-synaptic degradative enzyme examples?

Answer 55

initial class of antidepressants blocked monoamine oxidase (MAO)

Question 56

Inactivate synoptic degradation enzyme example?

Answer 56

nerve gas, Sarin gas, insecticides, drugs inhibit acetylcholinesterase (AChE)

Question 57

Blocks reuptake example?

Answer 57

cocaine, Ritalin, Adderall

Question 58

What are the effects of L-DOPA on Parkinson's disease symptoms

Answer 58

Degeneration of substantia nigra dopamine neurons Central goal: Boost dopamine synthesis in the neurons that remain

Question 59

What are the steps for L-DOPA

Answer 59

Steps: Tyrosine - TH enzyme - dopa - DOPA decarboxylase - DA

Question 60

Prevent synaptic release example?

Answer 60

botulinum toxin, tetanus toxin

Question 61

What is Optogenetics?

Answer 61

controlling the brain with light: Francis Crick Neurons don't respond to light - it is very specific and can be controlled Light can be precisely controlled: wavelength, intensity, pattern, on/offset Use of light-sensitive proteins from single-cell microbes to control neural activity