CH. 5 Dopamine

Question 1

where are most of catecholamine cell groups located

Answer 1

midbrain

Question 2

which dopamine cell groups are noradrenergic

Answer 2

A1-A7

Question 3

which catecholamine cell groups are dopaminergic?

Answer 3

A8-A17

Question 4

what are the three main dopamine pathways?

Answer 4

nigrostriatal
mesolimbic
mesocortical

Question 5

nigrostatial pathway

Answer 5

A9 axons
orginate in substancia nigra
extend to dorsal striatum

Question 6

what is the nigrostriatal pathway’s role? how does it do this?

Answer 6

facilitates voluntary movement
represses irrelevant actions, promotes needed actions

Question 7

what happens to people who have damage/dysfunction in the nigrostriatal pathway?

Answer 7

Parkinson’s disease
subconscious decision on how to properly move is taken away

Question 8

what neurotoxins can be used to damage the nigrostriatal pathway?

Answer 8

6-OHDA
MPTP

Question 9

mesolimbic pathway

Answer 9

A10 cell group
originates in ventral tegmental area
extends to nucleus accumbens and amygdala

Question 10

mesolimbic pathway role? how does it do it?

Answer 10

reward and motivational functions
forward movement towards/away from motivationally relevant stimuli

Question 11

mesocortical pathway

Answer 11

A10 cell group
originates in VTA
extends to frontal cortex
D1 receptors more expressed than D2

Question 12

what is the mesocortical pathways’ role? how does it do this?

Answer 12

modulation of cognitive functions
uses memories to inform actions in good/bad situations
works well only within optimum DA range

Question 13

how many DA receptors are there?

Answer 13

D1-D5

Question 14

what kind of receptors are the DA receptors

Answer 14

all metabotropic

Question 15

which recpetors are in the D1-like family?

Answer 15

D1, D5

Question 16

which receptors aretin the D2-like family?

Answer 16

D2, D3, D4

Question 17

what does D1 activation lead to?

Answer 17

adenylyl cyclase
cAMP synthesis

Question 18

what does D2 activation lead to?

Answer 18

cAMP inhibition
opposite of D1

Question 19

what is the prevalence of D1 and D2 in different brain regions?

Answer 19

found in all brain regions receiving DA innervation
separate populations within the region may be one or the other

Question 20

what separate roles can D2 receptors play on the same cell?

Answer 20

autoreceptor
postsynaptic receptor

Question 21

what affect to D2 antagonists have on D2 receptors?

Answer 21

increase DA release by blocking autoreceptor
reduce DA signalling on the postsynapse

Question 22

which DA receptor has a higher affinity to DA and by how much? what does this mean?

Answer 22

D2 receptor has 5x more affinity
higher concentrations of DA are needed to activate D1

Question 23

what kind of receptors are DA receptors found on glutamate/GABA terminals? what is their function?

Answer 23

heteroreceptors
modulates transmission of glutamate/GABA

Question 24

D1/D2 agonist

Answer 24

apomorphine

Question 25

apomorphine effect

Answer 25

increases locomotion regulateDA function in parkinson's when L-DOPA is not effective

Question 26

D1/D2 antagonist

Answer 26

flupenthixol

Question 27

flupenthixol effects at low and high dose

Answer 27

low dose; reduces motivation high dose; catalepsy

Question 28

what is catalepsy

Answer 28

lack of spontaneous movement

Question 29

how selective are DA receptor drugs between and within families?

Answer 29

good selectivity between families bad selectivity within family

Question 30

example of a drug with selectivity high between-family but low within-family? which family does it select for? antagonist or agonist?

Answer 30

haloperidol D2-like family antagonist

Question 31

experiment showing behavioural supersensitivity

Answer 31

control receives saline injections daily experimental receives haloperidol (D2 antagonist) injections daily both receive AMPH (DA agonist) early; hal blocks AMPH effect middle; hal does not block AMPH effect weened off hal; AMPH has greater effect then on control long term use increases D2 receptor density therefore making the cells more sensitive