Lecture 4 - Neurotransmitters And Neurotransmission

Question 1

Question: What is the effector neurotransmitter for the sympathetic nervous system?

Answer 1

Answer: Noradrenaline (NA) acting on adrenoceptors.

Question 2

Question: What is the effector neurotransmitter for the parasympathetic nervous system?

Answer 2

Answer: Acetylcholine (Ach) acting on muscarinic Ach receptors.

Question 3

Question: What is the ganglia neurotransmitter for both the sympathetic and parasympathetic nervous systems?

Answer 3

Answer: Acetylcholine (Ach) acting on nicotinic Ach receptors.

Question 4

Question: What are cotransmitters, and provide examples.

Answer 4

Cotransmitters involve the release of multiple neurotransmitters from a single synapse. Examples include ATP, NPY, NO, enkephalins, etc.

Question 5

Question: What are the subunits or subtypes of the NMDA receptor?

Answer 5

Answer: GluN1, GluN2A-D, GluN3A, B.

Question 6

Question: What type of receptor is the NMDA receptor?

Answer 6

Answer: Ligand-gated ion channel (Tetrameric).

Question 7

Question: What are the subunits or subtypes of the AMPA receptor?

Answer 7

Answer: GluA1-4.

Question 8

Question: What type of receptor is the AMPA receptor?

Answer 8

Ligand-gated ion channel (Tetrameric).

Question 9

Question: What are the subunits or subtypes of the Kainate receptor?

Answer 9

Answer: GluK1-5.

Question 10

Question: What type of receptor is the Kainate receptor?

Answer 10

Answer: Ligand-gated ion channel (Tetrameric).

Question 11

Question: What are the subunits or subtypes of the metabotropic glutamate receptor?

Answer 11

Answer: mGlu1-8.

Question 12

Question: What type of receptor is the metabotropic glutamate receptor?

Answer 12

Answer: GPCR (G-protein coupled receptor).

Question 13

Question: What are the subunits or subtypes of the GABAA receptor?

Answer 13

Answer: α1-6, β1-3, γ1-3.

Question 14

Question: What is neurotransmission?

Answer 14

Answer: Neurotransmission is the process by which signaling molecules, called neurotransmitters, are released by a neuron, travel across a synapse, and bind to receptors on a neighboring neuron.

Question 15

Question: What is the first process in neurotransmission?

Answer 15

Answer: Neurotransmitter synthesis.

Question 16

Question: Where are neurotransmitters stored?

Answer 16

Answer: Stored in vesicles.

Question 17

Question: What occurs to prevent the buildup of neurotransmitters outside the synapse?

Answer 17

Answer: Degradation of any leaked neurotransmitter.

Question 18

Question: What triggers the release of neurotransmitters into the synapse?

Answer 18

Answer: Action potential dependent release.

Question 19

Question: After release, where do neurotransmitters bind?

Answer 19

Answer: Neurotransmitter binds to postsynaptic receptors.

Question 20

Question: Besides binding to postsynaptic receptors, where else can neurotransmitters bind?

Answer 20

Answer: Neurotransmitter binds to presynaptic autoreceptors.

Question 21

Question: How are neurotransmitters deactivated?

Answer 21

Answer: Neurotransmitter deactivated either by reuptake or degradation.

Question 22

Question: What is the neurotransmitter involved in cholinergic neurotransmission?

Answer 22

Answer: Acetylcholine (ACh).

Question 23

Question: What enzyme synthesizes acetylcholine within the nerve terminal?

Answer 23

Answer: Choline acetyltransferase (ChAT).

Question 24

Question: Where is acetylcholine stored within the neuron?

Answer 24

Answer: In synaptic vesicles located within the presynaptic terminal.

Question 25

Question: What triggers the release of acetylcholine into the synaptic cleft?

Answer 25

Answer: The influx of calcium ions (Ca2+) into the presynaptic terminal triggered by an action potential.

Question 26

Question: What types of receptors does acetylcholine bind to on the postsynaptic membrane?

Answer 26

Answer: Nicotinic or muscarinic receptors.

Question 27

Question: What is the function of nicotinic receptors?

Answer 27

Answer: Nicotinic receptors are ligand-gated ion channels that, when activated, lead to the influx of sodium ions (Na+) and efflux of potassium ions (K+), resulting in depolarization of the postsynaptic membrane.

Question 28

Question: What is the function of muscarinic receptors?

Answer 28

Answer: Muscarinic receptors, which are G protein-coupled receptors, can activate or inhibit intracellular signaling pathways, leading to diverse physiological responses depending on the subtype.

Question 29

Question: How is the action of acetylcholine terminated?

Answer 29

Answer: The enzyme acetylcholinesterase (AChE) hydrolyzes acetylcholine into acetate and choline.

Question 30

Question: What happens to the choline after acetylcholine is hydrolyzed?

Answer 30

Answer: Choline is taken back up into the presynaptic terminal via a high-affinity choline transporter for resynthesis of acetylcholine, completing the cycle.

Question 31

Question: What are the major excitatory amino acids in CNS neurotransmission?

Answer 31

Answer: Glutamate and aspartate.

Question 32

Question: Name the inhibitory amino acids involved in CNS neurotransmission.

Answer 32

Answer: γ-aminobutyric acid (GABA) and glycine.

Question 33

Question: What are the monoamine neurotransmitters in the CNS?

Answer 33

Answer: Noradrenaline, serotonin, dopamine, and acetylcholine (ACh).

Question 34

Question: Besides amino acids and monoamines, what other types of neurotransmitters are involved in CNS neurotransmission?

Answer 34

Answer: Other neurotransmitters include purines (ATP), histamine, melatonin, and nitric oxide (NO).

Question 35

Question: Which are the main receptor groups involved in glutamate neurotransmission?

Answer 35

Answer: The main receptor groups are ionotropic receptors, such as AMPA, NMDA, and kainate receptors, and metabotropic receptors.

Question 36

Question: Describe the difference between fast (ionotropic) and slow (metabotropic) transmission in glutamate neurotransmission

Answer 36

Answer: Fast transmission occurs through ionotropic receptors, where the neurotransmitter directly opens ion channels, leading to rapid changes in membrane potential. Slow transmission occurs through metabotropic receptors, where neurotransmitter binding initiates intracellular signaling cascades, resulting in slower and longer-lasting effects on cellular function.

Question 37

Question: How do amines act as modulators of excitatory and inhibitory transmission?

Answer 37

Answer: Amines modulate excitatory and inhibitory transmission by influencing the activity of neurons and synapses.

Question 38

Question: Which receptor groups do amines primarily interact with?

Answer 38

Answer: Amines primarily interact with the receptor groups introduced earlier, including ionotropic and metabotropic receptors.

Question 39

Question: Where do the pathways of amines originate and terminate within the brain?

Answer 39

Answer: The pathways of amines originate from specific regions of the brain but terminate throughout the brain, allowing for widespread modulation of neuronal activity.

Question 40

Question: Why are amines considered important targets for many central nervous system (CNS) disorders?

Answer 40

Answer: Amines are important targets for many CNS disorders because of their crucial role in modulating neuronal activity, making them potential targets for therapeutic interventions.

Question 41

Question: What is co-transmission in neurotransmission?

Answer 41

Answer: Co-transmission refers to the transmission through a single synapse by means of more than one neurotransmitter.

Question 42

Question: Provide examples of neurotransmitters involved in co-transmission.

Answer 42

Answer: Examples include ATP, neuropeptide Y (NPY), dynorphin, and nitric oxide (NO).

Question 43

Question: How is ATP involved in co-transmission?

Answer 43

Answer: ATP is released as a co-transmitter and is sometimes considered a neurotransmitter itself.

Question 44

Question: What role does nitric oxide (NO) play in co-transmission?

Answer 44

Answer: Nitric oxide (NO) was once proposed to modulate synaptic plasticity, suggesting its involvement in co-transmission processes.

Question 45

Question: What is the primary function of presynaptic modulation in synaptic neurotransmission?

Answer 45

Answer: Presynaptic modulation primarily inhibits neurotransmitter release but can also enhance it under certain conditions.

Question 46

Question: What are autoreceptors, and how do they function in presynaptic modulation?

Answer 46

Answer: Autoreceptors are receptors located on the presynaptic terminal of a neuron that respond to the neurotransmitter released by that neuron, leading to a reduction in neurotransmitter release. For example, mGlu2 receptors modulate glutamate release when activated by glutamate.

Question 47

Question: What is a heteroreceptor, and how does it contribute to presynaptic modulation?

Answer 47

Answer: A heteroreceptor is a receptor located on the presynaptic terminal of a neuron that responds to a neurotransmitter other than its own ligand, leading to modulation of neurotransmitter release. For instance, GABA acting on GABAB receptors can reduce glutamate release.

Question 48

Question: What is synaptic plasticity, and where is it thought to be primarily mediated?

Answer 48

Answer: Synaptic plasticity refers to the ability of synapses to strengthen or weaken over time in response to activity. It is thought to be primarily mediated postsynaptically.

Question 49

Question: What role does synaptic plasticity play in memory formation?

Answer 49

Answer: Synaptic plasticity is considered the molecular correlate of memory, as it underlies the ability of neural circuits to store and retrieve information.

Question 50

Question: How does synaptic plasticity contribute to central sensitization associated with chronic pain?

Answer 50

Answer: Synaptic plasticity underlies central sensitization associated with chronic pain by strengthening synaptic connections in pain pathways, leading to increased sensitivity to pain signals and amplification of pain perception.

Question 51

Question: What are some consequences of aging on normal function in the nervous system?

Answer 51

Answer: Aging can lead to deterioration of normal function, including neurodegeneration and an increased role of inflammation in the nervous system.

Question 52

Question: How does chronic pain differ from normal pain function?

Answer 52

Answer: Chronic pain involves a maladaptive switch in function within the pain pathways, leading to persistent pain signals even in the absence of ongoing tissue damage or injury.

Question 53

Question: Are there any over-the-counter (OTC) medications directly acting on the brain?

Answer 53

Answer: No, there are no OTC medications directly acting on the brain. However, some herbal medicines, such as ginkgo biloba, claim to improve memory and cognitive function.

Question 54

Question: What is co-codamol, and how does it act on the central nervous system?

Answer 54

Answer: Co-codamol is an over-the-counter pain medication that contains codeine and paracetamol. Codeine acts on opioid receptors in the central nervous system to modulate pain pathways, providing relief from moderate to severe pain.

Question 55

Question: What is an agonist?

Answer 55

Answer: An agonist is a substance, whether it be a drug or a naturally occurring body substance, that directly causes a measurable response when it binds to a receptor. This response can be either excitatory or inhibitory.

Question 56

Question: Define affinity in the context of receptor binding.

Answer 56

Answer: Affinity refers to the binding strength or attraction between an agonist (or any drug) and its receptor. It determines how likely the agonist is to bind to the receptor.

Question 57

Question: What is efficacy regarding agonists?

Answer 57

Answer: Efficacy refers to the ability of an agonist (or any drug) to activate the receptor once it is bound, leading to the elicitation of a response. In other words, efficacy determines how well the agonist can produce the desired effect upon binding to the receptor.