Neurotransmitters

Question 1

What are the three criteria that classify a neurotransmitter?

Answer 1

1. They are synthesized and packed in presynaptic neurons
2. They are released in axon terminals
3. It produces a post-synaptic response

Question 2

What are the two methods of localization of neurotransmitters?

Answer 2

1. In situ hybridization
2. Immunocytochemistry

Question 3

What are the differences in the two methods of localization of neurotransmitters?

Answer 3

In situ hybridization - MRNA probe binding - labels cell bodies, cheap but time consuming

Immunocytochemistry - Antibodies recognize neurotransmitters/enzymes/transport - can label processes, short, sometimes is missing information on the cell body that the axon came from

Question 4

What two methods of study give information on neurotransmitters in studies using agonsists?

Answer 4

1. Micro-ionophoresis: Reproduction of effects using injection of agonist
2. Microelectrode - Electric stimulation of a molecule effect on postsynaptic EPSP/IPSP

Question 5

What are the two types of cholinergic receptors?

Answer 5

1. Nicotinergic
2. Muscarinic

Question 6

What do different receptor subtypes differ in other than structure?

Answer 6

They differ in antagonists

Question 7

What are the three subtypes of glutamatergic receptors?

Answer 7

1. AMPA
2. Kainate
3. NMDA

Question 8

What are characteristics of ionotropic receptors?

Answer 8

1. Rapid synaptic transmission
2. Sensitive to molecules and sometimes membrane potentials
3. It mediates membrane currents
4. It is selective for specific ions

Question 9

What is the mechanism of synthesis of acetylcholine?

Answer 9

It is made form acetyl-CoA + choline done by choline acetyltransferase

Question 10

What happens to Acetylcholine in the synaptic cleft?

Answer 10

It is broken down into choline and acetate by acetylcholinesterase

Question 11

What are the roles of acetylcholine in the body?

Answer 11

It is an effector of motor stimulation, and can be stimulatory or inhibitory in the sympathetic and parasympathetic nervous sytem

Question 12

What are the three amino acids looked at in class?

Answer 12

1. Glutamate
2. Glycine
3. GABA

Question 13

What NT is responsible for 80% of excitatory synapses in the CNS?

Answer 13

Glutamate (Glutamic acid)

Question 14

What is the role of GABA and how is it synthesized?

Answer 14

It is the principal inhibitory synapse NT and is synthesized from glu by Glutamate decarboxylase

Question 15

What are the two modes of action for Glycine?

Answer 15

1. co-activation by glutamate
2. It is an inhibitory NT

Question 16

What is the E of glutamatergic receptors?

Answer 16

0mV

Question 17

Which glutamatergic receptors are more rapid and are involved in the initial phase of the EPSP?

Answer 17

AMPAR/KainateR

Question 18

What are the three types of glutamatergic receptor in a glutamate synapse? What subsections of receptors are they in?

Answer 18

AMPAR/KAR, NMDAR = ionotropic
mGluR = metabotropic

Question 19

The AMPAR/KainateR receptors are permeable to what ions?

Answer 19

K+/NA+

Question 20

What ion is the plug for the NMDA receptors?

Answer 20

Mg2+

Question 21

What happens to the membrane voltage of the postsynaptic neuron when there is Mg2+ present in the synapse?

Answer 21

It plugs the NMDA receptors and therefore the cell is “partially depolarized” with a voltage of -35mV

Question 22

At what voltages are Glutamatergic cells considered depolarized?

Answer 22

above +30mV

Question 23

What removes the Mg2+ ion from blocking the NMDA receptors?

Answer 23

The depolarization of the cell from the opening of AMPAR

Question 24

What is the role of NMDAR?

Answer 24

It is a slower, longer phase of the glutamatergic EPSP. It is Ca2+ permeable and is associated with synaptic plasticity

Question 25

What are the two NTs responsible for inhibitory transmission?

Answer 25

GABA for most, and glycine for non-GABAergic inhibitory action

Question 26

What do GABARs bind?

Answer 26

Ethanol, benzodiazepine, and barbiturate

Question 27

When is the reversal of inhibitory synaptic potential with the flux of Cl- ions observed?

Answer 27

-70mV

Question 28

What is the structure of G-protein coupled reactors?

Answer 28

A single polypeptide with 7 alpha helix transmembrane domains

Question 29

What types of NTs bind to metabotropic receptors?

Answer 29

Peptides and Amines

Question 30

What indicates the activation/inactivation of G-proteins?

Answer 30

Activated - bound to GTP Inactivated - bound to GDP

Question 31

What are the 5 steps of metabotropic receptor action?

Answer 31

1. Floating G-protein 2. G protein separates when NT binds into Ggtp and Gby 3. The two complexes activate effector proteins 4. G hydrolyzes GTP back into GDP and inactivates 5. The two parts og the G-protein come back together and reassemble

Question 32

What is the shortcut pathway of a G-protein action?

Answer 32

The Gby directly opens a potassium channel

Question 33

What is the cascades of second messengers in G-protein action?

Answer 33

It is the Ggtp protein starting a long cascade of reactions

Question 34

What is the push pull principle in the cascade of second messengers in metabotropic brain receptors?

Answer 34

It means secondary reactions can inhibit and activate other reactions to create fine tuned responses

Question 35

What is a possibility of secondary messenger cascades and occurs in the PLC NT?

Answer 35

Cascades can split into multiple branches

Question 36

What is divergence and convergence of NT signals?

Answer 36

Divergence is the ability of one NT to effects many effectors in a ell and convergence is when one effector is affected by many NTs