Electrical activities of neurones & Basic neurochemistry

Question 1

What are some common neurotransmitters?

Answer 1

Glutamate, GABA, Dopamine, Serotonin, and Acetylcholine

Question 2

What determines if a ligand is a neurotransmitter?

Answer 2

It must be present in the presynaptic terminal, its release must be triggered by neural stimulation, experimental application to a postsynaptic area must elicit an identical response to presynaptic stimulation, its effects must be physiologically proportional to the presynaptic stimulus, and there must be a local mechanism to inactivate the substance.

Question 2

How is dopamine synthesized?

Answer 2

Phenylalanine is converted into tyrosine, which is then converted into L-DOPA by Tyrosine hydroxylase (TH). L-DOPA is finally converted into Dopamine by DOPA decarboxylase.

Question 2

What are the two subclasses of monoamines and their respective neurotransmitters?

Answer 2

Catecholamines (norepinephrine, epinephrine, and dopamine) and Indoleamines (serotonin).

Question 3

How can neurotransmitter signaling be terminated?

Answer 3

By enzymatic breakdown, diffusion, or reuptake

Question 4

What is the negative feedback control for Tyrosine hydroxylase (TH)?

Answer 4

TH is under negative feedback control of Dopamine.

Question 5

What are the characteristics and locations of D1 dopamine receptors?

Answer 5

They are highly conserved 7TM receptors, found in the striatum and abundantly in cortical and limbic regions.

Question 6

What are the characteristics and locations of D2 dopamine receptors?

Answer 6

They are primarily in the striatum and inhibit adenylate cyclase.

Question 7

Where are D3, D4, and D5 dopamine receptors mainly found?

Answer 7

Mainly in cortical and limbic regions.

Question 8

What can high levels of dopamine cause?

Answer 8

Euphoria and psychosis.

Question 9

What can low levels of dopamine cause?

Answer 9

Parkinsonism.

Question 10

Does dopamine cross the blood-brain barrier?

Answer 10

No, dopamine does not cross the blood-brain barrier.

Question 11

How do cocaine and amphetamine affect dopamine?

Answer 11

They block dopamine reuptake.

Question 12

What is the primary method of inactivation for serotonin?

Answer 12

Reuptake.

Question 13

What is the rate-limiting step in serotonin synthesis?

Answer 13

The availability of tryptophan.

Question 14

What is the metabolite of serotonin

Answer 14

5-HIAA, formed by MAO.

Question 15

What is the main neurotransmitter at the neuromuscular junction?

Answer 15

Acetylcholine (ACh).

Question 16

How is the action of acetylcholine terminated?

Answer 16

By acetylcholinesterase.

Question 17

What enzyme is involved in the synthesis of acetylcholine?

Answer 17

Choline acetyltransferase (CAT).

Question 18

What happens to Choline acetyltransferase (CAT) in Alzheimer’s Disease?

Answer 18

CAT decreases in Alzheimer’s Disease.

Question 19

What types of drugs are approved for the treatment of Alzheimer’s Disease and what do they do?

Answer 19

Acetylcholinesterase inhibitors such as Aricept, Exelon, and Reminyl.

Question 20

How do Atropine and Scopolamine affect acetylcholine receptors?

Answer 20

They block muscarinic receptors.

Question 21

What are some effects of Atropine?

Answer 21

It increases heart rate, slows GI motility, and dilates the pupils.

Question 22

How does Botulinum Toxin affect acetylcholine?

Answer 22

It can block acetylcholine release at the neuromuscular junction

Question 23

What is the most common excitatory neurotransmitter in the CNS?

Answer 23

Glutamate.

Question 24

What roles does glutamate play in the body?

Answer 24

Involved in excitotoxic injury, seizures, learning, memory, anxiety, depression, and psychosis

Question 24

At which receptors does glutamate act?

Answer 24

AMPA and NMDA receptors

Question 24

What is the major inhibitory neurotransmitter in the brain?

Answer 24

GABA.

Question 25

From what is GABA synthesized?

Answer 25

From glutamate by Glutamic acid decarboxylase.

Question 26

What happens when GABA binds?

Answer 26

GABA binding opens the chloride channel.

Question 27

What type of drugs are used to treat anxiety, seizures, and muscle spasms in relation to GABA?

Answer 27

Drugs that increase GABA affinity and activity.

Question 28

What is Bicuculline and what can it induce?

Answer 28

Bicuculline is an antagonist that can induce seizures.

Question 29

What is the mechanism of action of cocaine at the synapse?

Answer 29

Cocaine blocks the activity of dopamine, norepinephrine, and serotonin transporters, preventing their reuptake into the presynaptic terminal.

Question 30

What is the consequence of cocaine blocking reuptake?

Answer 30

Dopamine remains in the synapse and continues its stimulatory role, which is responsible for euphoria and the accompanying risk for abuse.

Question 31

What is the rate-limiting step in serotonin synthesis?

Answer 31

conversion of tryptophan to 5-hydroxy tryptophan by trypthophan hydroxylase

Question 32

How does the enzyme Tyrosine Hydroxylase (TH) activity relate to dopamine levels?

Answer 32

TH is under negative feedback control of dopamine

Question 33

A patient presents with symptoms of Parkinsonism. Which neurotransmitter system is likely affected and what is the associated level?

Answer 33

The dopamine system, specifically low levels of dopamine.

Question 34

A patient exhibits euphoria and psychosis. What neurotransmitter imbalance might be present?

Answer 34

High levels of dopamine

Question 35

A patient is diagnosed with Alzheimer's Disease. Which enzyme involved in acetylcholine synthesis is likely decreased, and what class of drugs is used for treatment?

Answer 35

Choline acetyltransferase (CAT) is decreased. Acetylcholinesterase inhibitors (e.g., Aricept, Exelon, Reminyl) are approved for treatment.

Question 36

A drug that increases GABA affinity and activity is likely used to treat what conditions?

Answer 36

Anxiety, seizures, and muscle spasms.

Question 37

What is the effect of Reserpine on neurotransmitter stores?

Answer 37

Reserpine depletes vesicular stores.

Question 38

What is the enzyme responsible for synthesizing GABA from glutamate?

Answer 38

Glutamic acid decarboxylase.