Neuropharmacology Questions

Correct answer: A

Naloxone is a competitive antagonist at opioid receptors, which means that it works by binding to the same receptors that opioid drugs bind to, but instead of activating those receptors like opioid drugs, naloxone blocks activity at them. Naloxone also causes opioid drugs that are already attached to the receptor to be displaced.

Correct answer: D

The sedating and anxiety-reducing effects of benzodiazepines are believed to be attributable to the drugs’ actions at receptors for the neurotransmitter gamma-aminobutyic acid, or GABA. By increasing GABA activity, these drugs reduce neural activity, which can help to reduce anxiety by reducing the occurrence of anxiogenic thoughts. Benzodiazepines are no longer a first-line option to treat anxiety, however, because they have a high potential to cause dependence.

Correct answer: C

Amphetamine enters neurons and disrupts the storage of monoamines (e.g., dopamine, norepinephrine, serotonin) in synaptic vesicles. This leads to high levels of free-floating monoamines inside the neuron. Amphetamine then can cause the monoamine transporters to run in reverse, leading to increased release of monoamines into the synaptic cleft. These elevated monoamine levels (especially dopamine & norepinephrine) are thought to be responsible for the main psychoactive effects of amphetamine.

Correct answer: B

Most of the effects of caffeine are thought to be traceable back to its action as an antagonist at receptors for the neurotransmitter adenosine, meaning it binds to and blocks adenosine receptors (reducing activity there). Adenosine receptors are thought to be involved in promoting sleep, so by blocking those receptors caffeine promotes wakefulness.

Correct answer: C

Neurotransmitter reuptake is a method neurons use to remove excess neurotransmitters from the synaptic cleft. The inhibition of reuptake leads to higher levels of neurotransmitters in the synaptic cleft. Thus, SSRIs increase serotonin levels in the synaptic cleft, an effect which is either directly or indirectly related to an improvement in the symptoms of depression.

Correct answer: A

Alcohol is thought to act as a positive allosteric modulator at GABA receptors, in the process increasing the effects of GABA. This increased GABA signaling may help to explain alcohol's sedative and anxiolytic effects. Alcohol also inhibits activity at glutamate receptors.

Correct answer: B

LSD’s activity at a subtype of serotonin receptor called the 5-HT2A receptor is critical to the drug’s psychedelic effects. LSD acts as a partial agonist at the 5-HT2A receptor, which means that it binds to the 5-HT2A receptor and generates a response that is a fraction of what the natural ligand, serotonin, generates. LSD also interacts with other receptors, although the role of these receptors in the effects of LSD is less clear.

Correct answer: C

Xanomeline (sold as xanomeline-trospium, or Cobenfy) is an acetylcholine receptor agonist. This means that it stimulates acetylcholine receptors (specifically M1 and M4 receptor subtypes). This is unique because most other antipsychotics primarily target dopamine and/or serotonin receptors.

Correct answer: D

Zolpidem exerts its effects by increasing activity at receptors for the neurotransmitter GABA. GABA is primarily an inhibitory neurotransmitter, and increasing GABA activity can promote sleep as GABA can decrease activity in parts of the brain that promote wakefulness.

Correct answer: C

Cocaine binds to and inhibits the transporters responsible for the reuptake of dopamine, norepinephrine, and serotonin (monoamines) from the synaptic cleft, increasing their levels and prolonging their effects at synapses in the brain.

Correct answer: B

Methadone is a full agonist at μ-opioid receptors (similar to other opioids). Taken orally, it has a slow onset and long half-life, providing steady effects that reduce withdrawal and cravings while also avoiding injection-related risks like blood-borne infections.

Correct answer: C

Ketamine and norketamine act as antagonists at the NMDA receptor, which means that they block the receptor and inhibit activity there. This action alone does not seem to be capable of fully explaining ketamine's antidepressant effects, but it is the main mechanism of the drug, and it may lead to downstream effects (e.g., new synapse formation) that help treat depression.

Correct answer: C

MAOIs block the activity of monoamine oxidase, the enzyme responsible for breaking down serotonin, norepinephrine, and dopamine in the synapse. This leads to increased availability of these neurotransmitters, which is thought to play a role in antidepressant effects.

Correct answer: D

When a substance binds to a receptor and causes a decrease in signaling below baseline at the receptor, it can produce effects that are opposite to those of a full agonist. These substances are called inverse agonists, and beta-carbolines are a good example of them.

Correct answer: B

SNRIs work primarily by inhibiting a mechanism called reuptake. In reuptake, a protein called a transporter transports excess neurotransmitter molecules out of the synaptic cleft, typically back into the neuron that released them. SNRIs inhibit the reuptake of serotonin and norepinephrine, thereby decreasing the activity of a protein that removes serotonin and norepinephrine from the synapse.

Correct answer: A

Nicotine primarily exerts its effects by activating, or acting as an agonist, at certain receptors for the neurotransmitter acetylcholine. These receptors, known as nicotinic acetylcholine receptors, are found throughout the central and peripheral nervous systems.

Correct answer: B

Beta blockers are antagonists at receptors called beta-adrenergic receptors, meaning they block these receptors. Beta-adrenergic receptors are normally activated by epinephrine and norepinephrine, and their activation increases heart rate and blood pressure (among other effects). Thus, by blocking beta-adrenergic receptors, beta-blockers can decrease heart rate and blood pressure and help to decrease physical symptoms of anxiety.

Correct answer: A

SNRIs work primarily by inhibiting a mechanism called reuptake. In reuptake, a protein called a transporter transports excess neurotransmitter molecules out of the synaptic cleft, typically back into the neuron that released them. SNRIs inhibit the reuptake of serotonin and norepinephrine, causing levels of these neurotransmitters in the synaptic cleft to rise.

Correct answer: A

Drugs that bind to a receptor at a different site from where an agonist binds and influence the function of the receptor are called allosteric modulators. Allosteric modulators may increase or decrease the likelihood of an agonist binding to a receptor, enhance or reduce the effects an agonist has when it does bind, or activate the receptor on their own.

Correct answer: D

Unlike first-generation antipsychotics that mainly block dopamine receptors, many atypical agents also target serotonin receptors. Most act as antagonists, while some newer drugs partially agonize certain serotonin receptors, allowing them to modulate rather than fully block signaling.

Correct answer: A

Most of the effects of caffeine are thought to be traceable back to its action as an antagonist at receptors for a neurotransmitter called adenosine. This means that caffeine binds to adenosine receptors and blocks adenosine from binding there and activating the receptor; thus, it reduces activity at the adenosine receptor.

Correct answer: C

Similar to the benzodiazepines, zolpidem exerts its effects by increasing activity at receptors for the neurotransmitter GABA. GABA is primarily an inhibitory neurotransmitter, and increasing GABA activity can promote sleep as GABA can decrease activity in parts of the brain that promote wakefulness.

Correct answer: D

Ketamine and its metabolite norketamine both act at a receptor for the neurotransmitter glutamate called the NMDA receptor. Glutamate is the primary excitatory neurotransmitter in the brain, and ketamine and norketamine act as antagonists at the NMDA receptor, which means that they block the receptor and inhibit activity there.

Correct answer: A

Tricyclic antidepressants are thought to work to treat depression by blocking the reabsorption, or reuptake, of neurotransmitters like serotonin and norepinephrine.

Correct answer: C

Allosteric modulators bind to a receptor at a different site from where an agonist binds and influence the function of the receptor. Allosteric modulators can increase or decrease the likelihood of an agonist binding to a receptor, enhance or reduce the effects an agonist has when it does bind, or activate the receptor on their own.

Correct answer: B

Studies suggest that DMT’s action at the 5-HT2A serotonin receptor is especially important for producing its characteristically intense visual hallucinations.

Correct answer: C

The active ingredients in kratom are thought to activate opioid receptors involved in pain relief to account for kratom’s analgesic and other opioid-like effects. Some refer to kratom alkaloids as "atypical opioids."

Correct answer: C

Psilocybin itself is not thought to be very psychoactive, but soon after it is ingested it is metabolized into a substance called psilocin, which is highly psychoactive. We don't have a complete understanding of how psilocin produces its effects, but its action at serotonin receptors is thought to be critical to the effects of the drug.

Correct answer: A

Most addictive drugs cause dopamine levels to increase, especially in areas of the brain that are considered part of the brain's reward system (e.g,. nucleus accumbens). While this relationship might seem to imply that dopamine causes pleasure, evidence suggests a more nuanced role for dopamine in addiction.

Correct answer: A

Agonism occurs when a drug binds to a receptor and causes a biological response. Agonists that can generate a maximal response at a receptor are called full agonists. Partial agonists are only able to generate a fraction of the possible response at a receptor.