49 Pharmacology: Dopaminergic Pathways

Question 1

Review of Dopamine

• Fill in the blanks

Answer 1

Question 2

Review of Dopamine

• What are the three major nuclei of dopamine origin?
  
  • Which one is located in the hypothalamus?

Answer 2

Question 3

Dopaminergic Pathways

• What are the 4 pathways?

Answer 3

Question 4

Nigrostriatal Pathway

• What is another name for this pathway?
• Where does this pathway start? Whre does it end?
• Function
  
  • Does this receive inhibitory or excitatory input from the motor cortex?
  • What kind of movement is involved with this pathway?
• What neurodegenerative disorder arises from the destruction of this pathway?

Answer 4

Question 5

Mesolimbic Pathway

• Where does this start and where does it project to?
  
  • What nucleus and cranial nerve is involved in this pathway?
• What types of behavior is this involved it?
• What kind of disorders arise from dysfunction in this pathway? (4)

Answer 5

Question 6

Mesocortical pathway

• This pathway starts the VTA and projects to 4 structures. What are they?
• How does this relate to conscious and human behavior?
• What other dopaminergic pathway is it often grouped with?

Answer 6

Question 7

Mesocortical + Mesolimbic Pathways (Mesocorticalmesolimic pathway)

• This pathway modules reward perception.
  
  • What happens to the mesolimbic pathway when it receives a “reward” stimulus?
• Reward Processing
  
  • What 3 structures influence the reward processing that occurs in the nucleus accumbens?
• What is the effect of stimulation of this pathway?

Answer 7

Question 8

Tuberoinfundibular Pathway

• Where does this pathway start? Where does it end?
• What kind of functions does this pathway modulate? (2)
  
  • How does this effect prolactin?

Answer 8

Question 9

Area Postrema Dopamine Receptors

• What is this the “center” of?
• Where is it located, in relation to the 4th ventricle?
• What structure allows this area to be a chemosensor for blood? How?
• What kind of dopamine receptors have a high density here?
  
  • What happens when these are stimulated?
  • Why are these a target for drugs?

Answer 9

Question 10

Dopaminergic Synapse

• Are dopamine receptors inotropic or metabotropic?
• Which dopamine receptors are excitatory?
  
  • What does this do to cyclic AMP in a cell?
• Which dopamine receptors are inhibitory?
  
  • What does this do to cyclic AMP in a cell?
  • What does it do to potassium currents and calcium currents?

Answer 10

Question 11

Dopamine Receptors

• Does this show the locations of D1 or D2 receptors in the brain?

Answer 11

D2

Question 12

Dopamine Receptors

• Does this show the locations of D1 or D2 receptors in the brain?

Answer 12

D1

Question 13

Basal Nuclei

• What are the 2 functions that this modulates?
• What 3 types of input does this integrate?
• How does this help with performing learned movements?

Answer 13

Question 14

Basal Nuclei: RElationship with Cortex + Thalamus

• What do these structures form?
• Thalamus
  
  • Thalamic Output to Cortex
    
    • Is this inhibitory or excitatory
  • What do the basal nuclei do to the thalamus?
• Release Inhibition Model
  
  • How does tonic inhibition related to this model?

Answer 14

Question 15

Striatum

• What does dopamine do to this?
• What 2 structures make up the striatum?
• What function does the striatum have?
  
  • Where do signals from the striatum go?

Answer 15

Question 16

Striatum

• The striatum integrates many signals from different inputs.
  
  • Which inputs are associated with glutamate? (2)
    
    • With dopamine? (1)
    • With Acetylcholine/GABA? (1)
• What kind of neuron is the principal neuron of the striatum?
  
  • What neurotransmitter are these associated with?
  • How does their structure relate to their function?
  • What other types of neurons are located here (10%)?
    
    • What neurotransmitter are these associated with? Is this inhibitory or excitatory?

Answer 16

Question 17

Medium Spiny Neurons

• What are all medium spiny neurons?
• What dictates the amount of neurotransmitter that these cells release?
  
  • What neurotransmitter is this?
• What 2 pathways do these neurons project to?

Answer 17

Question 18

Direct and Indirect Pathways of the basal nuclei

• What pathway is associated with focused movement?
• What pathway is associated with unfocused movement?
• What structure has dopaminergic projections to the striatum?
  
  • What structure in the striatum receives these projections?
  • What type of neurons synapse with the dopaminergic projections?

Answer 18

Question 19

Dopamine and the Basal Nuclei

• Indirect Pathway
  
  • What dopamine receptors is this associated with?
  • What structure provides dopaminergic input to INACTIVATE this pathway?
• Direct Pathway
  
  • What dopamine receptors is this associated with?
  • What structure provides dopaminergic input to ACTIVATE this pathway?

Answer 19

Question 20

Direct Pathway of the basal nuclei

• Putamen
  
  • What glutaminergic fibers project to this?
  • What dopaminergic fibers project to this?
  • What type of receptor causes excitation by the above two inputs?
• Globus Pallisdus (Internal)
  
  • What type of input does the putamen give this structure?
  • What type of activity does this reduce?
  • What does the above answer do to thalamic GABA levels?
• What is the net result of the activation of this pathway? (Mention the thalamus and cortex)

Answer 20

Question 21

Indirect Pathway of the basal nuclei

• Putamen
  
  • What glutaminergic fibers project to this?
    
    • What does this do to D2 cells in the putamen?
  • What dopaminergic fibers project to this?
    
    • What does this do to D2 cells in the putamen?

Answer 21

Question 22

Indirect Pathway of the basal nuclei

• Where do D2 neurons in the putamen project to, and what neurotransmitter do they release?
  
  • What does this due to the GABEergic neurons in this structure? How does this affect the subthalamic nucleus?
• What is the net result on the thalamus and cortex?

Answer 22

Question 23

Antipsychotics

• What receptors do typical antipsychotics target, and in what pathway?
• Why do ADRs occur from this?

Answer 23