Cyclic adenosine monophosphate (cAMP) functions as a
dif-fusible second messenger after activation of
(A) Acetylcholine M 1 receptors
(B) Beta 1 adrenoceptors
(C) 5-HT 3 receptors
(D) GABA A receptors
This transmitter is mostly located in diffuse neuronal systems
in the CNS, with cell bodies particularly in the raphe nuclei. It
appears to play a major role in the expression of mood states,
and many antidepressant drugs are thought to increase its
functional activity.
(A) Acetylcholine
(B) Dopamine
(C) Glutamate
(D) Serotonin
(E) Substance P - ANSWER D (Amine transmitters thought to be involved in the
control of mood states include norepinephrine and serotonin. Cell
bodies of serotonergic neurons are found in the raphe nuclei.
Many of the drugs used for the treatment of major depressive
disorders act to increase serotonergic activity in the CNS. The
answer is D.)
Cyclic adenosine monophosphate (cAMP) functions as a
dif-fusible second messenger after activation of
(A) Acetylcholine M 1 receptors
(B) Beta 1 adrenoceptors
(C) 5-HT 3 receptors
(D) GABA A receptors
,(E) Glutamate NMDA receptors - ANSWER B (Metabotropic receptors modulate voltage-gated
ion chan-
nels directly (membrane-delimited action) and also by the
formation of diffusible second messengers through G-protein-
mediated effects on enzymes involved in their synthesis. An
example of the latter type of action is provided by the β 1
adrenoceptor, which generates cAMP via the activation of
adenylyl cyclase. The answer is B.)
One of the first neurotransmitter receptors to be identified
in the CNS is located on the Renshaw cell in the spinal cord.
Activation of this receptor results in excitation via an
increase in cation conductance independently of G protein-
coupled mechanisms. Which of the following compounds is
most likely to activate this receptor?
(A) Aspartate
(B) Dopamine
(C) GABA
(D) Nicotine
(E) Serotonin - ANSWER D (Nicotinic receptors on the Renshaw cell are activated by the
release of ACh from motor neuron collaterals. This results in
the release of glycine, which, via interaction with its receptors
on the motor neuron, causes membrane hyperpolarization, an
example of feedback inhibition. The receptors were so named
because of their activation by nicotine. The answer is D.)
This neurotransmitter, found in high concentrations in cell
,bodies in the pons and brain stem, can exert both excitatory
and inhibitory actions. Multiple receptor subtypes have
been identified, some of which are targets for drugs that can
exert both CNS and peripheral actions.
(E) Norepinephrine - ANSWER E (The brief description might apply to several CNS
neurotrans-mitters, including serotonin and possibly dopamine (neither
of which is listed). Cell bodies of noradrenergic neurons
located in the pons and brain stem project to all levels of
the CNS. Most of the subclasses of adrenergic receptors that
occur in peripheral tissues are present in the CNS. Agents that
activate presynaptic α 2 receptors on such neurons (eg, cloni-
dine, methyldopa) decrease central noradrenergic activity, an
action thought to result in decreased vasomotor outflow. The
answer is E.)
A 43-year-old very overweight man complains of not
sleeping well and feeling tired during the day. He tells his
physician that his wife is the cause of the problem because
she wakes him up several times during the night because of
his loud snores. This appears to be a breathing-related sleep
disorder, so you should probably write a prescription for
(A) Buspirone
(B) Eszopiclone
, (C) Flurazepam
(D) Secobarbital
(E) None of the above - ANSWER E (Benzodiazepines and barbiturates are contraindicated
in breathing-related sleep disorders because they further com-
promise ventilation. In obstructive sleep apnea (pickwickian
syndrome), obesity is a major risk factor. Buspirone is a selec-
tive anxiolytic not a hypnotic. The best prescription you can
give this patient is to lose weight. The answer is E.)
Which statement concerning the barbiturates is accurate?
(A) Abstinence syndromes are more severe during withdrawal
from phenobarbital than from secobarbital
(B) Alkalinization of the urine accelerates the elimination
of phenobarbital
(C) Barbiturates may increase the half-lives of drugs metabo-
lized by the liver
(D) Compared with barbiturates, the benzodiazepines
exhibit a steeper dose-response relationship
(E) Respiratory depression caused by barbiturate overdosage
can be reversed by flumazenil - ANSWER B (Withdrawal symptoms from use of the shorter-
acting barbi-
turate secobarbital are more severe than with phenobarbital.
The dose-response curve for benzodiazepines is flatter than
that for barbiturates. Induction of liver drug-metabolizing
enzymes occurs with barbiturates and may lead to decreases in
half-life of other drugs. Flumazenil is an antagonist at BZ
receptors and is used to reverse CNS depressant effects of
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