Pharm - Introduction To CNS Pharmacology

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Pharm - Introduction To CNS Pharmacology - Quiz

A person that has central nervous system disorders or ailments needs specialized care and specific medication for the various ailments. It is therefore important for a pharmacist or medical practitioner to have adequate information on the various drugs. If you just covered introduction to CNS pharmacology take the test and jog your memory.


Questions and Answers
  • 1. 

    Which of the following statements regarding CNS drug action on synaptic potentials are correct? (Check all that apply)

    • A.

      A drug-induced EPSP usually makes the membrane potential less negative

    • B.

      An IPSP may be produced by drugs that cause opening of Cl- channels

    • C.

      An IPSP may be produced by drugs that cause opening of K+ channels

    • D.

      Most CNS drugs affect synaptic potential by activating or inhibiting NA+/K+ ATPase

    • E.

      All drug-induced EPSP and IPSP are very short-lasting potentials (less than 5 milliseconds)

    Correct Answer(s)
    A. A drug-induced EPSP usually makes the membrane potential less negative
    B. An IPSP may be produced by drugs that cause opening of Cl- channels
    C. An IPSP may be produced by drugs that cause opening of K+ channels
    Explanation
    Answer: ABC
    (Katzung, pp 340, Golan pp 94)
    By definition an excitatory post synaptic potential (EPSP) occurs when the membrane potential
    of the postsynaptic cell becomes less negative (depolarization) so making the neuron in an
    “excited” state (action potential generation is facilitated). Conversely an inhibitory postsynaptic
    potential occurs when the membrane potential of the postsynaptic cell becomes more negative.
    (hyperpolarization). This can happen either by increasing the negative charges inside the cell
    (when Cl- channels open, Cl- enters the cell since the concentration of Cl- outside is higher
    than the concentration inside) or by decreasing the positive charges inside the cell (when K+
    channels open, K+ exits the cell since the concentration of K+ inside is higher than the
    concentration outside ).
    D) CNS drugs do not act on NA+/K+ ATPase. Actually this enzyme is very seldom a drug
    target. A notable exception are cardiac glycosides, whose mechanism of action involves a
    specific blockade of the enzyme.
    E) EPSP and IPSP can be either fast (few milliseconds) or slow (few seconds).

    Rate this question:

  • 2. 

    CNS drugs often act on a specific neurotransmitter system. Which of the following statements correctly pairs the system with the drug class that mainly affects it?

    • A.

      Serotonergic system - Opioids

    • B.

      Cholinergic system - MAO inhibitors

    • C.

      Dopaminergic system - Phenothiazines

    • D.

      Noradrenergic system - Benzodiazepines

    • E.

      GABAergic system - Tricyclic antidepressants

    Correct Answer
    C. Dopaminergic system - Phenothiazines
    Explanation
    Answer: C
    (Katzung, pp 463, Brunton pp 462)
    Phenothiazines, butyrophenones as well as other neuroleptic drugs mainly interfere with the
    dopaminergic system by blocking dopaminergic receptors. This blockade seems to underlie
    both their clinical usefulness and their major adverse effects.
    A) Opioids act on the endorphinergic system.
    B, E) MAO inhibitors and tricyclic antidepressants mainly act on the noradrenergic and the
    serotonergic systems
    D) Benzodiazepines mainly act on the GABAergic system

    Rate this question:

  • 3. 

    Which of the following statements correctly matches the CNS receptor with the appropriate postreceptor mechanism? (Check all that apply)

    • A.

      M3 muscarinic - decreased NA+ conductance

    • B.

      Alpha-1 adrenergic - decreased Ca++ conductance

    • C.

      GABA A - increased Cl- conductance

    • D.

      Glycine r - decreased Cl- conductance

    • E.

      NMDA - decreased cation conductance

    • F.

      Beta-1 adrenergic - increased cAMP

    • G.

      5-HT3 - increased cation conductance

    Correct Answer(s)
    C. GABA A - increased Cl- conductance
    F. Beta-1 adrenergic - increased cAMP
    G. 5-HT3 - increased cation conductance
    Explanation
    Answer: CFG
    (Katzung, pp 345, Golan pp 82)
    All GABA receptors are inhibitory. Therefore they must hyperpolarize the postsynaptic
    membrane. GABA A receptors do so by increasing Cl- conductance whereas GABA B receptors
    do the same by increasing K+ conductance. All beta receptors are metabotropic and act by
    increasing the synthesis of the second messenger cAMP. 5-HT3 receptors are mainly
    excitatory. Therefore they must depolarize the postsynaptic membrane. By increasing cation
    conductance Na+ can enter the cell and depolarization occurs.
    A) M3 receptors are mainly excitatory. A decrease in Na+ conductance would cause an
    inhibitory effect at the postsynaptic membrane. Actually activation of these receptors causes
    the increased synthesis of IP3/DAG
    B) Alpha-1 adrenergic receptors are excitatory. A decrease in Ca++ conductance would cause
    an inhibitory effect at the postsynaptic membrane. Actually activation of these receptors
    causes the increased synthesis of IP3/DAG
    D) Glycine receptors are inhibitory and cause hyperpolarization of the postsynaptic membrane
    by increasing, not decreasing, Cl- conductance.
    E) NMDA receptors are glutamate receptors. All glutamate receptors are excitatory and cause
    depolarization of the membrane by increasing, nor decreasing, cation conductance.

    Rate this question:

  • 4. 

    Some CNS depressant drugs act on a system which is critical in maintaining tonic inhibitory control on most other neuronal systems. Which of the following systems is the target for those drugs?

    • A.

      Noradrenergic

    • B.

      Serotonergic

    • C.

      Cholinergic

    • D.

      Dopaminergic

    • E.

      GABAergic

    • F.

      Endorphinergic

    Correct Answer
    E. GABAergic
    Explanation
    Answer: E
    (Katzung, pp 344, Brunton pp 330)
    The GABAergic system is the most important inhibitory system in the brain. GABA neurons are
    short interneurons located throughout the cerebrum and cerebellum, as well as in the spinal
    cord.
    Several CNS drugs , including anxiolytics (i.e. benzodiazepines), hypnotics (i.e. zolpidem) and
    anticonvulsants (i.e. barbiturates, gabapentin, vigabatrin) exert their CNS depressant actions
    by increasing, with different mechanisms, GABA activity.
    A, B, C, D) All these systems are not purely inhibitory, but can exert excitatory or inhibitory
    effects according to the receptors activated and the target tissue.
    F) The endorphinergic system is an inhibitory system but it controls mainly pain circuits and is
    not as ubiquitous as the GABAergic system.

    Rate this question:

  • 5. 

    Which the following statements related to GABA A and GABA B receptors are correct? (Check all that apply)

    • A.

      GABA A receptors are G-protein coupled receptors

    • B.

      GABA A receptors activation leads to increased Na+ conductance

    • C.

      GABA B receptors activation leads to IPSP

    • D.

      GABA A receptors blockade leads to decreased Cl- conductance

    • E.

      GABA B receptors blockade leads to increased K+ conductance

    Correct Answer(s)
    C. GABA B receptors activation leads to IPSP
    D. GABA A receptors blockade leads to decreased Cl- conductance
    Explanation
    Answer: CD
    (Katzung, pp 345, Brunton pp 330)
    GABA B receptors activation leads to opening of K+ channels. This causes a hyperpolarization
    of the postsynaptic membrane (K+ exits from the cell) and therefore the production of IPSP.
    GABA receptors activation directly opens Cl- channels on postsynaptic membrane, so causing
    an increase of Cl- conductance. GABA A receptors blockade does the opposite.
    A) GABA A ionotropic, GABA B receptors are metabotropic, i.e. G-protein coupled..
    B) GABA receptors do not regulate Na+ channels.
    E Actually GABA B receptors activation leads to increased K+ conductance. GABA B receptors
    blockade does the opposite.

    Rate this question:

  • 6. 

    A 32-year-old man, recently diagnosed with partial seizure, started a treatment with felbamate, a drug that is thought to act by blocking NMDA receptors in the brain. Which of the following systems was most likely affected by the drug?

    • A.

      Noradrenergic

    • B.

      Cholinergic

    • C.

      Histaminergic

    • D.

      Dopaminergic

    • E.

      Serotonergic

    • F.

      GABAergic

    • G.

      Glutamatergic

    Correct Answer
    G. Glutamatergic
    Explanation
    Answer: G
    (Katzung, pp 385, Brunton pp 520)
    Glutamate is important excitatory neurotransmitter in the brain. Glutamate receptors include
    NMDA and Ampa receptors. Drugs, like felbamate, that seem to act by blocking these
    receptors can be used effectively as anticonvulsants.
    A, B, C, D, E) These systems are not exclusively excitatory and therefore drugs affecting these
    systems are not used as anticonvulsants.
    G) The GABAergic system is a central inhibitory system. Drugs that increase the activity of this
    system (like benzodiazepines and barbiturates) are currently used as anticonvulsants.

    Rate this question:

  • 7. 

    A 25-year-old woman presented to the psychiatric hospital describing a one year history of anxiety. She has been feeling tense most of the time, was often irritable and found hard to concentrate because of a great deal of distress. She was prescribed an anxiolytic drug and a cycle of psychotherapy. Which of the following neurotransmitter systems is most likely involved in the therapeutic action of the prescribed drug?

    • A.

      Cholinergic

    • B.

      Histaminergic

    • C.

      Glutamatergic

    • D.

      GABAergic

    • E.

      Dopaminergic

    • F.

      Endorphinergic

    Correct Answer
    D. GABAergic
    Explanation
    Answer: D
    (Katzung, pp 356, Koda-Kimble, pp 76-2)
    The most commonly used anxiolytic drugs are benzodiazepines, which act by increasing the
    GABAergic activity of the brain. Other drugs frequently used include buspirone (a serotonin
    agonist) and SSRIs. This would indicate that the serotonergic system is also involved in
    the pathogenesis of anxiety disorders.
    A, B, C, E, F) these systems do not seem to play a major role in anxiety disorders.

    Rate this question:

  • 8. 

    A 25-year-old woman was brought to the Emergency Room because of a generalized tonic-clonic seizure. Her husband stated that his wife has been suffering from epilepsy since childhood, but the seizures were only partially controlled by medication. Which of the following pairs of neurotransmitters are thought to be mainly involved in seizure disorders?

    • A.

      GABA and serotonin

    • B.

      GABA and glutamate

    • C.

      GABA and acetylcholine

    • D.

      Serotonin and glutamate

    • E.

      Serotonin and acetylcholine

    • F.

      Acetylcholine and glutamate

    Correct Answer
    B. GABA and glutamate
    Explanation
    Answer: B
    (Katzung, pp 380, Golan, pp 194)
    Epilepsy is a chronic recurrent disorder of cerebral function that may be characterized by
    repeated seizures. The essence of epilepsy is probably a chronic low seizure threshold which
    can be due to several mechanisms. A leading mechanism postulates that the cause of seizures
    is either the attenuation of pre and/or postsynaptic inhibition (mainly due to a genetic or
    postpathologic hypofunction of GABA neurons) or an increased effectiveness of excitatory
    synapses (mainly due to a genetic or postpathologic hyperfunction of glutamate neurons).
    A, C, D, E, F) (see explanation above)

    Rate this question:

  • 9. 

    A 34-year-old man who is a heavy smoker started a medical assisted program to quit smoking. Therapy included the administration of clonidine, an agonist at alpha-2 presynaptic receptors which is believed to act mainly on noradrenergic neurons in the brain. Which of the following areas of the brain is the richest in noradrenergic neurons?

    • A.

      Median Raphe Nucleus

    • B.

      Stria Terminalis

    • C.

      Locus Ceruleus

    • D.

      Substantia Nigra

    • E.

      Thalamus

    Correct Answer
    C. Locus Ceruleus
    Explanation
    Answer: C
    (Katzung, pp 520, Brunton, pp 452)
    Most noradrenergic neurons in the brain are found in the locus ceruleus, a bluish area on each
    side of the median eminence of the brain stem. Locus ceruleus sends a particularly large
    number of projections to the amygdala and hippocampus, where norepinephrine release is
    thought to mediate emotion and memory formation. Another brain region which is rich in
    noradrenergic neurons is the lateral tegmental area of the reticular formation.
    Clonidine activates presynaptic alpha-2 receptors located on noradrenergic terminals and this
    decreases norepinephrine release from those terminals. It seems that this reduction of central
    adrenergic activity is the basis of the therapeutic effect of the drug in case of withdrawal from
    addicting drugs, including nicotine and opioids.

    Rate this question:

  • 10. 

    A 23-year-old woman presented to his physician complaining of a distressing and behavior. For the past months she has experienced an irresistible urge to check that everything was in a certain order at home and found hard to get out of the house because she needed to control that the door was locked again and again. She admitted that she had an irrational fear that things were not perfect. Which of the following neurotransmitter has been most consistently implicated in this disorder?

    • A.

      Acetylcholine

    • B.

      Norepinephrine

    • C.

      GABA

    • D.

      Serotonin

    • E.

      Glutamate

    Correct Answer
    D. Serotonin
    Explanation
    Answer: D
    (Katzung, pp 490, Koda-Kimble, pp 76-38)
    The patient is most likely suffering from an obsessive-compulsive disorder. In this disorder the
    person feels driven to perform certain acts according to rigid rules, in order to prevent or
    reducing distress. The person is aware that the behavior is excessive and inappropriate but
    can’t stop it. Serotonin has been frequently implicated in obsessive-compulsive disorder. This
    is mainly related to the good therapeutic response obtained with serotonergic medications like
    SSRIs.
    A, B, C, E) (see explanation above)

    Rate this question:

  • 11. 

    Receptors located on CNS nerve terminals can be autoreceptors or heteroreceptors. Which of the following descriptions refers to heteroreceptors? (Check all that apply)

    • A.

      5-HT1A receptors on nerve terminals of most neurons of Raphe Nucleus

    • B.

      M2 cholinergic receptors on the motor nerve terminals

    • C.

      Alpha-2 receptors on nerve terminals of most neurons of Locus Ceruleus

    • D.

      D2 receptors on nerve terminals of nigrostriatal pathway

    • E.

      GABA A receptors on nerve terminals of cortical pyramidal neurons

    • F.

      Glutamate receptors on nerve terminals mesolimbic pathway

    Correct Answer(s)
    E. GABA A receptors on nerve terminals of cortical pyramidal neurons
    F. Glutamate receptors on nerve terminals mesolimbic pathway
    Explanation
    Answer: EF
    (Katzung, pp 88, Brunton, pp 148)
    By definition heteroreceptors are receptors located on nerve terminals that regulate the
    release of a transmitter different from the one that activate them, whereas autoreceptors are
    receptors located on nerve terminals that regulate the release of the transmitter which activate
    them. Cortical pyramidal neurons are glutamatergic and therefore GABA A receptors located on
    nerve terminal of those neurons are heteroreceptors. Neurons of the mesolimbic pathway are
    dopaminergic and therefore glutamate receptors located on nerve terminal of those neurons
    are heteroreceptors.
    A) Most neurons of the Raphe Nucleus are serotonergic an therefore 5-HT1A receptors on
    nerve terminals of most neurons
    B) Motor neurons are cholinergic and therefore M2 receptors located on nerve terminal of
    those neurons are autoreceptors.
    C) Most neurons of Locus Ceruleus are noradrenergic and therefore alpha-2 receptors located
    on nerve terminal of those neurons are autoreceptors.
    D) Neurons of the mesolimbic pathway are dopaminergic and therefore D2 receptors located
    on nerve terminal of those neurons are autoreceptors.

    Rate this question:

  • 12. 

    A 45-year-old woman, admitted to a psychiatric hospital, has been standing immobile for several hours with one of his arm stretched upwards. The patient was mute, unresponsive and did not appear aware of her surrounding. When placed in another awkward posture the patient maintained that posture for a long time without apparent distress. .Which of the following neurotransmitter has been consistently implicated in the patient’s syndrome?

    • A.

      Norepinephrine

    • B.

      Acetylcholine

    • C.

      Histamine

    • D.

      Dopamine

    • E.

      GABA

    Correct Answer
    D. Dopamine
    Explanation
    Answer: D
    (Katzung, pp 463, Koda-Kimble, pp 78-3)
    The patient is most likely suffering from the catatonic subtype of schizophrenia which is
    characterized by motor immobility and abnormal posture maintained for a long time ( the so
    called “waxy flexibility”). A number of theories related to major neurotransmitter systems has
    been proposed to explain the symptoms of schizophrenia. Of these, the dopamine hypothesis
    states that the illness results from an excessive dopaminergic activity in mesolimbic and
    mesocortical pathways. The dopamine hypothesis is the most fully developed and is supported
    by several lines of evidence, including the fact that most antipsychotic drugs block D2
    receptors and there is a very good correlation between clinical potency of these drugs and
    their in vitro affinity for these receptors. Other two major hypotheses of schizophrenia are the
    serotonin hypothesis (it is known that alteration in serotonergic functioning affects multiple
    neurotransmitter systems), and the glutamate hypothesis that proposes a hypofunctional
    glutamate system in schizophrenia.
    A, B, C, E) (see explanation above)

    Rate this question:

  • 13. 

    A 31-year-old woman seeks evaluation in a psychiatric clinic. She reports episodic feeling of sadness since adolescence, but she has noticed a gradual worsening in her mood over the past three weeks. She has depressed mood most of the day, has lost interest in any leisure activity, has difficulty sleeping, poor appetite, low energy, feeling of guilt and recurrent though of death. Which of the following pairs of neurotransmitters are most likely involved in the patient’s disorder?

    • A.

      Glutamate and serotonin

    • B.

      Norepinephrine and glutamate

    • C.

      Glutamate and acetylcholine

    • D.

      Serotonin and norepinephrine

    • E.

      Serotonin and acetylcholine

    • F.

      Acetylcholine and norepinephrine

    Correct Answer
    D. Serotonin and norepinephrine
    Explanation
    Answer: D
    (Katzung, pp 482, Koda-Kimble, pp 79-4)
    The patient has six of the symptoms that are essential features of major depression. Among
    the biochemical theories of depression the strongest evidence is for an abnormality in
    serotonergic and noradrenergic function. This amine hypothesis of depression is supported by
    several lines of evidence including the fact that most antidepressant drugs increase the
    availability of serotonin and norepinephrine in the CNS.
    A, B, C, E, F) Glutamate and acetylcholine do not seem to be involved in the pathogenesis of
    depression

    Rate this question:

  • 14. 

    The following table shows the relative activities of five new drugs, which are able to increase the availability of specific CNS neurotransmitters into the synaptic cleft. Examine the table and identify which one of the drugs A, B, C, D, E, is most likely to be effective in the treatment of major obsessive-compulsive disorders. (+ represents the degree of increased availability; - represents negligible effect)

    • A.

      A

    • B.

      B

    • C.

      C

    • D.

      D

    • E.

      E

    Correct Answer
    C. C
    Explanation
    Answer: C
    (Katzung, pp 490, Koda-Kimble, pp 76-37)
    Drugs that increase the availability of serotonin in the synaptic cleft (like SSRIs and
    clomipramine) are the only first line medication treatments for obsessive compulsive disorders.
    The pathophysiology of these disorders seems to involve orbitofrontal-limbic-basal ganglia
    circuits and, after treatment with SSRIs, functional imaging studies have shown a normalization
    of hyperactivity in areas such as the caudate, orbitofrontal lobes and cingulate cortex.
    A, B, D, E) (see explanation above)

    Rate this question:

  • 15. 

    A 34-year-old man was brought to the emergency room after a serious car accident. He begun to experience sever pain throughout the body. Which of the following triplets of neurotransmitters most likely acted to decrease pain signaling in this patient?

    • A.

      Norepinephrine, GABA, glutamate

    • B.

      Glutamate, norepinephrine, opioid peptides

    • C.

      Histamine, acetylcholine, GABA

    • D.

      Histamine, acetylcholine, opioid peptides

    • E.

      Glutamate, GABA, serotonin

    • F.

      Opioid peptides, norepinephrine, serotonin

    Correct Answer
    F. Opioid peptides, norepinephrine, serotonin
    Explanation
    Answer: F
    (Katzung, pp 501, Golan, pp 233)
    Opioid peptides, serotonin and norepinephrine are the three major neurotransmitters that act in
    the CNS to decrease pain signaling and producing analgesia. Endogenous opioids are
    released at several CNS sites in response to noxious stimuli, including the spinal cord, the
    thalamus and the cortex. Endogenous opioids can also modulate pain transmission indirectly,
    by activating the following pathways that descend from the brainstem to the dorsal horn:
    a) a noradrenergic pathway from the locus ceruleus. Norepinephrine, released from these
    projections in the spinal cord, activates alpha-2 receptors (the primary receptors for
    norepinephrine in the CNS) located on nociceptive neurons of the dorsal horn. This activation
    causes hyperpolarization of the neuron so inhibiting nociceptive transmission.
    b) a serotonergic pathway from the raphe nuclei. Serotonin, released from these projections in
    the spinal cord, activates serotonergic receptors located on nociceptive neurons of the dorsal
    horn. This activation causes hyperpolarization of the neuron so inhibiting nociceptive
    transmission
    A, B, C, D, E) (see explanation above)

    Rate this question:

  • 16. 

    A 57-year-old woman, suffering from initial insomnia, was prescribed a hypnotic drug that increases the activity of a major neurotransmitter system in the brain. Which of the following neurotransmitter systems is most likely involved in the therapeutic action of that drug?

    • A.

      Cholinergic

    • B.

      Noradrenergic

    • C.

      Glutamatergic

    • D.

      GABAergic

    • E.

      Dopaminergic

    • F.

      Endorphinergic

    Correct Answer
    D. GABAergic
    Explanation
    Answer: D
    (Katzung, pp 357, Brunton, pp 405)
    Most drugs used to relieve insomnia (i.e. benzodiazepines, zolpidem) are GABAergic drugs,
    that is they increase the activity of GABA, the most abundant inhibitory neurotransmitter in the
    brain.
    A, B, C, E, F) Drugs acting on these neurotransmitter systems are not currently used to treat
    insomnia.

    Rate this question:

  • 17. 

    A 76-year-old man, suffering from Alzheimer’s disease, was prescribed a drug that increases the central levels of a neurotransmitter thought to play an important role in cognitive functions. Which of the following neurotransmitters was most likely increased by that drug?

    • A.

      Acetylcholine

    • B.

      Norepinephrine

    • C.

      Histamine

    • D.

      GABA

    • E.

      Dopamine

    Correct Answer
    A. Acetylcholine
    Explanation
    Answer: A
    (Katzung, pp 1010 , Brunton, pp 539)
    The main class of drugs currently approved for the treatment of Alzheimer’s disease are
    cholinesterase inhibitors, which increase the central levels of acetylcholine. Patients with
    Alzheimer’s disease have a significant loss of cholinergic neurons especially in the temporal
    lobe and entorhinal cortex, two areas responsible for maintaining memory and cognition.
    B, C, D, E) (see explanation above)

    Rate this question:

  • 18. 

    A 18-year-old boy was brought to the emergency room by a friend after being found acting crazy in a discotheque. The man admitted he had smoked an “angel dust”, the street name for phencyclidine. Which of the following neurotransmitters seems mainly involved in the mechanism of action of that drug?

    • A.

      Acetylcholine

    • B.

      Histamine

    • C.

      Glycine

    • D.

      GABA

    • E.

      Glutamate

    Correct Answer
    E. Glutamate
    Explanation
    Answer: E
    (Katzung, pp 524, Brunton, pp 625)
    Phencyclidine is a hallucinogenic drug that binds with high affinity and blocks the N-methyl-Daspartate
    (NMDA) subtype of glutamate receptor in the brain. A closely related drug, ketamine,
    seems to act in a similar way ,is used as a general anesthetic agent but is sometimes abused
    (with the street name of special K).
    A, B, C, D) (see explanation above)

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  • 19. 

    A 28-year-old man with a long history of poly-drug abuse states he feels an intense euphoric sensation every time he self administered any illicit drug. Which of the following neurotransmitters, released in the nucleus accumbens, is thought to mediate the rewarding effect of most abused drugs?

    • A.

      Acetylcholine

    • B.

      Norepinephrine

    • C.

      Histamine

    • D.

      GABA

    • E.

      Dopamine

    Correct Answer
    E. Dopamine
    Explanation
    Answer: E
    (Katzung, pp 518, Graham, pp 65)
    Acute rewarding effects of most abused drug are thought to be mediated by and increased in
    synaptic levels of dopamine in nucleus accumbens, a nucleus that seems to comprise a major
    portion of the brain reward circuitry. Because of this, dopamine is thought to play an important
    role in the development of drug dependence.
    A, B, C, D) (see explanation above)

    Rate this question:

  • 20. 

    A 79-year-old woman complained of sharp headache in the temporal area. Fifteen minutes later she lost consciousness and was brought to the Emergency Room. A CT scan showed a diffuse brain hemorrhage and the diagnosis of left middle cerebral artery stoke was made. Which of the following neurotransmitters has been implicated as a cause of cell death following stroke?

    • A.

      Acetylcholine

    • B.

      Norepinephrine

    • C.

      GABA

    • D.

      Serotonin

    • E.

      Glutamate

    Correct Answer
    E. Glutamate
    Explanation
    Answer: E
    (Katzung, pp 347, Brunton, pp 332)
    Although glutamate is essential for brain function, too much glutamate can be toxic to neurons.
    When blood flow to the brain tissue is impaired, mechanism of normal glutamate reuptake
    stops and glutamate accumulates into the synaptic cleft. This high concentration of glutamate
    can activate a large amount of glutamate ionotropic receptors, so triggering a huge influx of
    Ca++ into postsynaptic cells. This intracellular high Ca++ level can cause neuronal death. This
    property of glutamate is called excitotoxicity and can play an important role in a number of
    brain disorders including stroke and epilepsy.
    A, B, C, D) These neurotransmitters do not cause excitotoxicity.

    Rate this question:

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