Deck 5: Catecholamines

Question 1

Increased levels of DA or NE in the nerve terminal decreases the rate of catecholamine synthesis by affecting the action of

A) tyrosine hydroxylase.
B) aromatic acid decarboxylase.
C) dopamine β-hydroxylase.
D) DOPA.

Answer 1

A

Question 2

Which of the following most accurately represents the synthesis of the catecholamines?

A) DOPA $\rightarrow$ tyrosine $\rightarrow$ dopamine $\rightarrow$ norepinephrine
B) Tyrosine $\rightarrow$ DOPA $\rightarrow$ dopamine $\rightarrow$ norepinephrine
C) Tyrosine $\rightarrow$ dopamine $\rightarrow$ DOPA $\rightarrow$ norepinephrine
D) DOPA $\rightarrow$ dopamine $\rightarrow$ tyrosine $\rightarrow$ norepinephrine

Answer 2

Tyrosine $\rightarrow$ DOPA $\rightarrow$ dopamine $\rightarrow$ norepinephrine

Question 3

Once synthesis has occurred, a protein called the _______ is responsible for packaging molecules of dopamine into membrane packets for release.

A) autoreceptor
B) terminal receptor
C) vesicular monoamine transporter
D) dopamine transporter

Answer 3

C

Question 4

Under conditions of high excitatory input, a dopaminergic neuron can switch from _______ to _______, causing an increase in extracellular neurotransmitter levels.

A) single-spiking mode; burst mode
B) inhibitory; excitatory
C) dopaminergic; adrenergic
D) phasic; tonic

Question 5

Catecholamine levels can be decreased by _______, which serves to _______.

A) reserpine; block tyrosine hydroxylase
B) α-methyl-para-tyrosine; inhibit uptake into vesicles
C) α-methyl-para-tyrosine; block tyrosine hydroxylase
D) Adderall; inhibit reuptake

Question 6

A group of mice is given reserpine as part of an experiment. Behaviorally, these animals would be expected to show

A) repetitive head and limb movements.
B) sedation.
C) stereotyped behaviors.
D) increased activity.

Question 7

Activation of terminal autoreceptors inhibits dopamine release, in part, by

A) increasing Cl^- entry into the terminal.
B) decreasing Ca²⁺ entry into the terminal.
C) preventing reuptake into vesicles.
D) decreasing Na⁺ entry into the terminal.

Question 8

The initial breakdown of catecholamines involves the enzymes

A) catechol-O-methyltransferase and tyrosine hydroxylase.
B) monoamine oxidase and homovanillic acid.
C) catechol-O-methyltransferase and monoamine oxidase.
D) monoamine oxidase and tyrosine hydroxylase.

Question 9

High levels of MHPG, HVA, and VMA in the blood and urine can indicate

A) increased transporter activation.
B) hypertension.
C) dysfunctional receptors.
D) level of catecholaminergic activity in the nervous system.

Question 10

The first means of inactivation of the catecholamines is

A) reuptake by transporter proteins.
B) reuptake by autoreceptors.
C) metabolism by monoamine oxidase.
D) rapid diffusion.

Question 11

Which drugs can bypass the requirement for cellular excitation and cause a release of catecholamines independently of nerve cell firing?

A) Amphetamine and methamphetamine
B) Dopamine and tyrosine
C) Clonidine and lofexidine
D) Albuterol and levalbuterol

Question 12

_______ and _______ exert their pharmacological effects by blocking monoamine reuptake.

A) Cocaine; phenelzine
B) Cocaine; tricyclic antidepressants
C) Clonidine; tricyclic antidepressants
D) Clonidine; yohimbine

Question 13

A patient with Parkinson's disease is being treated with a drug that has been shown to show improvements cognitive functioning. The patient's doctor notices that the drug is working and thus increases the dose only to find that the increased dose has a negative effect cognitive functions. Which drug is the doctor likely administering?

A) Tyrosine
B) Reserpine
C) Valbenazine
D) Methylphenidate

Question 14

A(n) _______ inhibitor of catecholamine vesicular uptake allows some action of the target protein while the cell synthesizes new protein molecules that have not been subjected to the inhibitory drug, whereas a(n) _______ inhibitor does not.

A) COMT; MAO
B) MAO; COMT
C) reversible; irreversible
D) irreversible reversible

Question 15

The drugs Ritalin and Adderall are used to treat attention-deficit/hyperactivity disorder (ADHD) and work by _______ reuptake.

A) blocking prolactin
B) enhancing prolactin
C) enhancing DA and NE
D) blocking DA and NE

Question 16

The A9 and A10 cell groups are associated with the _______ and the _______, respectively.

A) ventral tegmental area; locus coeruleus
B) ventral tegmental area; substantia nigra
C) substantia nigra; ventral tegmental area
D) substantia nigra; locus coeruleus

Question 17

Dopaminergic cell bodies in the VTA send projections to the nucleus accumbens and the amygdala via the _______ dopamine pathway.

A) nigrostriatal
B) mesocortical
C) mesolimbic
D) tuberohypophyseal

Question 18

Patients with Parkinson's disease patients are often administered a catechol-O-methyltransferase (COMT) inhibitor because COMT

A) interacts poorly with other drugs frequently used to treat Parkinson's disease.
B) metabolizes a major portion of the administered l-DOPA before it reaches the brain.
C) prevents the conversion of tyrosine to DOPA.
D) builds up very quickly in the body and can lead to adverse reactions.

Question 19

The dopamine pathway most important for regulating voluntary movement is the _______ pathway.

A) nigrostriatal
B) mesocortical
C) mesolimbic
D) tuberohypophyseal

Question 20

D₁ and D₂ dopamine receptor subtypes have _______ effects on adenylyl cyclase, which synthesizes cAMP; D₁ receptors _______ it, and D₂ receptors _______ it.

A) opposite inhibit; stimulate
B) opposite; stimulate; inhibit
C) similar; inhibit; also inhibit
D) similar; stimulate; also stimulate

Question 21

Which statement regarding D₂ dopamine receptors is false?

A) They are found only in the hypothalamus.
B) They function as autoreceptors.
C) They inhibit adenylyl cyclase and decrease the synthesis of cAMP.
D) They can enhance K⁺ channel opening via activation of a G protein.

Question 22

A scientist investigating a newly identified receptor in rat cortex determines that it is a metabotropic receptor that regulates membrane-bound K⁺ channels in some cells and inhibits adenylyl cyclase. Based on these findings, the receptor is most likely a(n)

A) β-adrenoceptor.
B) D₁-like dopamine receptor.
C) D₂-like dopamine receptor.
D) autoreceptor.

Question 23

Which statement regarding receptor up-regulation is false?

A) It can lead to behavioral supersensitivity to an agonist.
B) It can result from chronic treatment with an antagonist.
C) It can result from depletion of normal neurotransmitter input.
D) It occurs only in the case of autoreceptors.

Question 24

6-hydroxydopamine (6-OHDA) is a(n) _______ used to _______.

A) neurotoxin; damage catecholamine neurons
B) antagonist; block catecholamine receptors
C) transporter inhibitor; prevent catecholamine reuptake
D) agonist; activate catecholamine receptors

Question 25

Which symptom would not be expected in an animal treated bilaterally with 6-OHDA?

A) Decreased interest in motivated behaviors such as eating and drinking
B) Difficulty initiating movement
C) Increased locomotor activity
D) Sensory neglect

Question 26

To create a dopamine-deficient (DD) mouse that retains the ability to produce NE, the gene for _______ is selectively restored in noradrenergic neurons.

A) tyrosine hydroxylase
B) 6-hydroxydopamine
C) dopamine β-hydroxylase
D) DOPA

Question 27

A _______ receptor antagonist, which is thought to block DA receptors in the limbic system, would likely be prescribed to a patient with schizophrenia.

A) D₁
B) D₂
C) D₄
D) D₅

Question 28

Recent research indicates that supersensitivity to a drug can be reduced by _______ of striatal D₂ receptor occupancy.

A) alternating the drug of choice with placebo to allow for an increase
B) complete withdrawal from the drug to allow for a reduction
C) an increased dose of a drug to allow for increase
D) intermittent drug dosing to allow for a reduction

Question 29

The D₂/D₃ receptor agonist bromocriptine (Cycloset), is used to treat type 2 diabetes by regulating blood insulin and glucose levels. The mechanism of action of this drug is thought to be _______ nervous system resulting in reduced glucose production.

A) inhibition of the sympathetic
B) activation of the sympathetic
C) inhibition of the parasympathetic
D) activation of the peripheral

Question 30

Dopamine transporter knockout mice are hyperactive compared to wild-type mice because

A) they produce more dopamine than wild-type mice.
B) they have fewer receptors than wild-type mice.
C) there is consistent activation of postsynaptic DA receptors.
D) they cannot synthesize dopamine.

Question 31

The main location of noradrenergic cell bodies in the CNS is the

A) ventral tegmental area.
B) locus coeruleus.
C) substantia nigra.
D) hypothalamus.

Question 32

In the CNS, dopaminergic cell bodies are found primarily in the _______, whereas adrenergic cell bodies are found in the _______.

A) midbrain; pons and medulla
B) midbrain; hypothalamus
C) pons and medulla; forebrain
D) frontal cortex; cerebellum

Question 33

Which statement about norepinephrine (NE) is false?

A) It acts in both the central nervous system and the autonomic nervous system.
B) It is thought to play a role in arousal.
C) NE terminals are found throughout the forebrain.
D) NE-producing cell bodies are widespread throughout the brain.

Question 34

Which feature of norepinephrine makes its action similar to that of a hormone?

A) It is released from the locus coeruleus into the general circulation.
B) It is released from the hypothalamus into the general circulation.
C) It is released from the adrenal glands into the general circulation.
D) None of the above; it does not show action similar to a hormone.

Question 35

Norepinephrine produced in cell bodies in the sympathetic chain ganglia

A) enters the general circulation.
B) can act on the heart and other organs.
C) causes arousal by acting on the medulla.
D) cannot cross the blood-brain barrier.

Question 36

Noradrenergic receptors

A) are ionotropic.
B) inhibit adenylyl cyclase.
C) are metabotropic.
D) stimulate adenylyl cyclase.

Question 37

$\beta$ ₁- and $\beta$ ₂-adrenoceptors _______, whereas ?₂-receptors _______.

A) stimulate adenylyl cyclase; enhance free Ca²⁺ levels
B) inhibit adenylyl cyclase; stimulate adenylyl cyclase
C) stimulate adenylyl cyclase; inhibit adenylyl cyclase
D) increase K⁺ channel opening; inhibit adenylyl cyclase

Question 38

Working memory can be enhanced by activation of _______ in the prefrontal cortex (PFC), whereas activation of _______ in the PFC has detrimental effects on cognitive function.

A) α₁-adrenoreceptors; β₁-adrenoreceptors
B) α₂-adrenoreceptors; α₁-adrenoreceptors
C) β₂-adrenoreceptors; β₁-adrenoreceptors
D) α₂-adrenoreceptors; β₁-adrenoreceptors

Question 39

Injections of isoproterenol and/or phenylephrine into the lateral hypothalamus of the rat show that

A) NE is involved in hunger.
B) α₁- and β-receptors are involved in wakefulness.
C) α₁- and β-receptors are involved in sedation.
D) NE is important in pupil dilation.

Question 40

In the passive avoidance learning paradigm, learning is demonstrated by

A) increased latency to enter the dark compartment.
B) decreased latency to enter the dark compartment.
C) increased physiological response to foot shock.
D) increased latency to enter the light compartment.

Question 41

You are crossing a busy street and carefully look both ways for oncoming traffic. As soon as you step into the street someone near you pulls you back as you suddenly notice a car approaching. Your heart is pounding and you suddenly feel sweaty. Which brain structure plays a key role in your response to this upsetting event and subsequent memory of it?

A) Substantia nigra
B) Frontal cortex
C) Basolateral amygdala
D) Ventral tegmental area

Question 42

Signs of opioid withdrawal include increased heart rate, diarrhea, and elevated blood pressure, which can be relieved by stimulating

A) µ opioid receptors.
B) D₂ autoreceptors.
C) NE transporters.
D) α₂-autoreceptors.

Question 43

Why are adrenergic agonists and antagonists important in the treatment of many nonpsychiatric medical conditions?

A) NE cells innervate many diverse brain regions.
B) Movement disorders like Parkinson's are caused by changes in NE systems.
C) Alterations in brain NE can cause disorders of sleeping and eating.
D) Adrenergic receptors are found in a wide variety of peripheral organs.

Question 44

The β₂-adrenoreceptor agonists albuterol and levalbuterol are used to treat _______ because they _______.

A) asthma and COPD; constrict blood vessels in the bronchial lining and reduce congestion
B) asthma and COPD; relax the bronchial muscles and create a wider airway
C) colds; constrict blood vessels in the nose and reduce congestion
D) hypertension; decrease the rate of contraction of the heart

Question 45

The main reason for administering albuterol via inhaler is that it

A) reduces congestion in the nose.
B) reduces cardiovascular side effects.
C) is the most cost-effective method of delivery.
D) acts very quickly on the respiratory system to provide relief.

Question 46

In the treatment of hypertension, prazosin _______, whereas propranolol _______.

A) blocks α₁-receptors and causes dilation of blood vessels; blocks β-receptors in the heart and decreases the contractile force
B) blocks α₁-receptors and causes constriction of blood vessels; activates β-receptors in the heart and increases the contractile force
C) activates α₁-receptors and causes dilation of blood vessels; activates β-receptors in the heart and decreases the contractile force
D) activates α₁-receptors and causes constriction of blood vessels; blocks β-receptors in the heart and increases the contractile force

Question 47

Hypertension and _______ can be treated with β-receptor antagonists.

A) depression
B) drug addiction
C) asthma
D) anxiety

Question 48

Why might a physician prescribe metoprolol rather than propranolol to treat high blood pressure?

A) It works only in the central nervous system.
B) It is more effective because it acts as an antagonist at all adrenergic receptors.
C) It dilates blood vessels by antagonizing α₁-receptors.
D) It has fewer side effects because it selectively antagonizes β₁-receptors.

Question 49

β-antagonists, such as propranolol, help patients with generalized anxiety by _______.

A) reducing some of the physical symptoms associated with anxiety.
B) acting directly on brain regions involved in anxiety.
C) increasing sympathetic nervous system activity, which makes the person feel better able to cope with anxiety-producing situations.
D) causing sedation.

Question 50

Describe the steps involved in the synthesis and metabolism of the catecholamines, including all the enzymes involved.

Question 51

Write a coherent and informative paragraph incorporating the following terms: phasic release, extracellular DA, tonic release, burst mode, VTA.

Question 52

Explain how the two forms of the human COMT gene code for slightly different proteins and affect the prefrontal cortex differently.

Question 53

Describe the anatomy and briefly explain the function of the four main dopaminergic systems of the brain.

Question 54

Compare and contrast the D₁ and D₂ receptors, including consequences of activation.

Question 55

Write a coherent and informative paragraph incorporating the following terms: behavioral supersensitivity, 6-OHDA, antagonist, receptor up-regulation, D₂ receptors.

Question 56

Describe restless legs syndrome. Which dopamine receptor has been used to treat this syndrome?

Question 57

Describe the relationship between noradrenergic α₂-autoreceptors and opiate withdrawal, including pharmacological evidence supporting this relationship.

Question 58

Describe the evidence linking wakefulness to orexin and NE in the lateral hypothalamus.

Question 59

Draw a curve describing the relationship between noradrenergic activity in the prefrontal cortex and working memory. Explain what the curve shows and describe the presumed receptor mechanisms responsible.

Question 60

Describe the release and actions of norepinephrine (NE) and epinephrine (EPI) associated with one-trial passive avoidance learning, which is used to study emotional memory consolidation.