L21- GABA and Dopamine

Question 1

Major inhibitory neurotransmitter of the nervous system

Answer 1

GABA

Question 2

GABA activation at neurons causes _______

Answer 2

hyperpolarization

Question 3

how is GABA synthesised

Question 4

what are the two classifications of GABA receptors

Answer 4

Ionotropic and Metabotropic

Question 5

function of GABAa + c receptors

Answer 5

opens chloride channels causing a influx of negative charge into the cell causing hyperpolarisation

Question 6

function of GABAb receptors

Answer 6

indirectly opens potassium or calcium channels via g proteins causing the release of positive charge from the neuron causing hyperpolarization

Question 7

activation of GABAa receptors in the synapse

Answer 7

causes rapid inhibition and return to steady state

Question 8

activation of extra synaptic GABAa receptors

Answer 8

excess release of GABA presynaptically (spill over) causes tonic inhibition

Question 9

GABAc receptors expression

Answer 9

in the retina and axonally on bipolar
cells

Question 10

what is the suggested role of GABAc function

Answer 10

may have a role in myopia, pain and some neurological disorders

Question 11

Side effects of GABAc modification

Answer 11

GABAc receptors are relatively sparse in the body relative to other GABA receptor types

modification of these receptors has limited systematic side effects

Question 12

where are GABAb receptors located

Answer 12

glial cells
pre and post-synaptic neurons

Question 13

activation of PRE-synaptic GABAb receptors

Answer 13

Inhibit the presynaptic neuron and the calcium dependent neurotransmitter release (auto-reception)

Question 14

activation of POST-synaptic GABAb receptors

Answer 14

receptors activate potassium channels and lead to a slow hyperpolarisation

Question 15

How many GAT subtypes are there

Answer 15

4

Question 16

location of GAT 1

Answer 16

mainly located on presynaptic terminals, axon initial segments and glial cells

Question 17

location of GAT 2/3

Answer 17

mainly located on glial cells

Question 18

how is GAT transport mediated

Answer 18

secondary active transport
- Co transport 2 sodium, 1 chloride with 1 GABA

Question 19

role dopamine in the CNS

Answer 19

modulated excitation and inhibition depending on location

Has a diverse role in the nervous system:
* Movement
* Reward
* Motivation

Question 20

how many dopamine subtypes are there

Answer 20

5- D1-5

Question 21

how many dopamine classes are there

Answer 21

2 - D1&2

Question 22

Function and location of D1 class

Answer 22

D1 class activate Gαs/olf to stimulate cAMP production by adenylyl cyclase
- increasing PIP2 hydrolysis
- Ca+ mobilization
- PKC activation

Question 23

location of D1 class

Answer 23

only found post-synaptically

Question 24

Function and location of D2 class

Answer 24

activate G αi/o to inhibit adenylyl cyclase
- decreases cAMP
- increases K+ currents
- decreases Ca+ currents

Question 25

location of D2 class

Answer 25

pre and post synaptically

Question 26

activation of PRE-synaptic D2 class receptors

Answer 26

Low amounts of dopamine activate D2 receptors causes negative feedback (auto-reception)

Question 27

bi phasic response of DA receptors

Answer 27

D2 presynaptic neuron are activated by lower levels of dopamine then post synpatic neurons

Question 28

how is negative feedback mediated at the presynaptic neuron

Answer 28

Ca+ channel that are needed to release vesicles of neurotransmitters into the synapse are blocked K+ channels are opened hyperpolarizing the cell

Question 29

L-DOPA

Answer 29

L-DOPA is the DA precursor and indirect agonist for DA receptors Used for dopamine replacement therapy Many uses for antipsychotic outcomes

Question 30

DAT function

Answer 30

Returns DA to the presynaptic terminals via secondary active transport (reuptake) Cotransports 2 sodium, 1 chloride into the cell along with 1 dopamine

Question 31

pharmacological relevance of DAT

Answer 31

blocking (cociane) or reversing DAT (amphetamine) pump dopamine into the synapse

Question 32

monoamine oxidase inhibitors

Answer 32

MAOs are enzymes that break down monoamines - inhibiting this process maintains the effects of dopamine

Question 33

TRUE or FALSE: neurons release only one kind of neurotransmitters

Answer 33

FALSE: Neurons in the olfactory bulb release both GABA and DA