Neurotransmitters

Question 1

What is synaptic transmission?

Answer 1

Information transfer across the synapse that requires the release of neurotransmitters and their interaction with postsynaptic receptors

Question 2

What are the main features of synaptic transmission?

Answer 2

Rapid timescale
Diversity
Adaptability 
Plasticity 
Learning and memory

Question 3

What are the steps in transmission of information?

Answer 3

Information reception
Integration
Rapid transmission

Question 4

What are synapses?

Answer 4

Presynaptic nerve terminal
Synaptic cleft (20-100nm)
Postsynaptic region
Specialised structures to which neurotransmission is restricted to

Question 5

What are the 3 stages of synaptic transmission?

Answer 5

Biosynthesis- packaging and release of neurotransmitters
Receptor action
Inactivation

Question 6

Give examples of neurotransmitters

Answer 6

Amino acids e.g. glutamate and glycine
Amines e.g, noradrenaline and dopamine
Neuropeptides e.g. opioid peptides

Question 7

How does the concentrations of neurotransmitters vary?

Answer 7

mM to nM

Question 8

How does the time scale of neurotransmission vary?

Answer 8

microseconds - milliseconds

Rapid or slower effects

Question 9

Summarise the action of neurotransmission

Answer 9

Neurones receive multiple transmitter influences which are integrated to produce a wide range of functional responses

Question 10

What are the steps of activation a CNS synapse?

Answer 10

Arrival of action potential 
Causes VGCC's to open
Rapid influx of calcium 
Vesicle fusion and exocytosis
Release of transmitter
Moves across synaptic cleft
Activates receptor on postsynaptic membrane

Question 11

How do rapid release rates occur?

Answer 11

Vesicles are filled and docked in the synaptic zone

Special proteins enable fusion and exocytosis

Question 12

What are vesicular proteins targets for?

Answer 12

Neurotoxins

Question 13

Give some examples of neurotoxins

Answer 13

Alpha latroxin (from black widow)
Simulates transmitter release to depletion 

Tetanus toxin, C tetani causes paralysis

C botulinum causes flaccid paralysis

Question 14

What are the two main classes of receptors?

Answer 14

Ion channel receptors- fast response

G-protein couples reactors- slow response

Question 15

Give examples of when ion channel receptors are used

Answer 15

CNS- Glutamtes binds to GABA

NMJ- Ach at nicotinic recpeptors

Question 16

Give examples of when G-protein coupled receptors are used

Answer 16

ACh at muscarinic receptors

Question 17

What are the main features of ion channel-linked receptors

Answer 17

Rapid activation
Rapid info flow
Multiple subunit combinations- distinctly functional properties

Question 18

What are the two main types of glutamate receptors?

Answer 18

AMPA- fast excitatory synapses, linked to Na channels

NMDA- slow excitatory synapses

Question 19

What are the steps of on glutamine production?

Answer 19

Glutamate synthesised from glucose via TCA and transamination
Glutamate reversibly binds post-synaptic receptors
Rapid uptake of glutamate by excitatory amino acid transporters
Glutamte enzymatically modified by glutamine synthetase to glutamine in glial cell

Question 20

What can seizures be caused by?

Answer 20

Abnormal cell firing causes seizures associated with excess glutamate in the synapse

Question 21

What’s the deal with epilepsy?

Answer 21

One of most common neurological conditions affecting 50 million people worldwide
Recurrent seizures due to abnormal neuronal excitability
Disease can be disabling

Question 22

What occurs at a GABAgernic synapse?

Answer 22

GABA formed by decarboxylation of glutamate by glutamic acid decarboxylase
GABA reversibly binds post-synaptic receptors
Rapid uptakes of GABA by GABA transporters
GABA enzymatically modified by GABA-transaminase to succinate semialdehyde in glial cell

Question 23

What is the structure of GABA receptor?

Answer 23

Pentameric organisation

Pharmacologically important binding domains

Question 24

What drugs facilitate GABA transmission?

Answer 24

Antiepileptic
Anxiolytic
Sedative
Muscle relaxant