Which of the following actions most likely mediate the adverse effect reported by the patient?

Correct Answer: B

Rationale: The correct answer is B: Decreased acetylcholine release from cholinergic terminals. Acetylcholine release from cholinergic terminals contributes to the parasympathetic response, which can cause adverse effects such as bradycardia. By decreasing acetylcholine release, the parasympathetic response is reduced, leading to a more balanced autonomic control of the heart rate. Activation of cardiac dopamine receptors (choice A) and β receptors (choice C) would usually have positive effects on the heart, while blockade of cardiac M receptors (choice D) would exacerbate the adverse effects by blocking the already decreased parasympathetic response.

Correct Answer: C

Rationale: The correct answer is C: Haloperidol. The patient's syndrome is most likely caused by Haloperidol, an antipsychotic drug known to cause extrapyramidal symptoms such as dystonia, akathisia, and parkinsonism. Imipramine (A) is a tricyclic antidepressant associated with anticholinergic effects. Temazepam (B) is a benzodiazepine used for insomnia. Fluoxetine (D) is a selective serotonin reuptake inhibitor used for depression and not typically associated with extrapyramidal symptoms. Therefore, the most likely culprit is Haloperidol due to its known side effect profile.

Correct Answer: C

Rationale: Rationale: The correct answer is C because increased expression of brain-derived neurotrophic factor (BDNF) is a common mechanism underlying the therapeutic effectiveness of long-term therapy with most antidepressants. BDNF promotes neuronal survival, growth, and differentiation, which are essential for mood regulation and combating depression. A: Inhibition of central monoamine metabolism is a common mechanism of action for some antidepressants, but not all. B: Upregulation of central postsynaptic adrenoceptors is not a common mechanism of action for antidepressants. D: Decreased hippocampal neurogenesis is associated with depression, and antidepressants aim to increase neurogenesis.

Correct Answer: B

Rationale: The correct answer is B: 5-HT serotonergic receptors. This is because drugs that affect serotonin receptors can cause adverse effects such as serotonin syndrome, which presents with symptoms like confusion, agitation, and hyperthermia. Beta-1 adrenergic receptors (A) are involved in heart function, not typically associated with adverse effects. M cholinergic receptors (C) mediate the parasympathetic nervous system and are unlikely to cause adverse effects in this scenario. Alpha-1 adrenergic receptors (D) are involved in vasoconstriction and blood pressure regulation, not commonly linked to adverse drug effects in this context.

Correct Answer: A

Rationale: The correct answer is A: Bupropion. Bupropion is a norepinephrine-dopamine reuptake inhibitor (NDRI), meaning it blocks the reuptake of both norepinephrine and dopamine by brain neurons, leading to increased levels of these neurotransmitters in the brain. This mechanism of action is specifically associated with bupropion and not the other choices. Methylphenidate primarily affects dopamine reuptake, Lamotrigine is an anticonvulsant that modulates glutamate release, and Aripiprazole is a partial dopamine agonist. Therefore, only bupropion matches the criteria of decreasing reuptake of both norepinephrine and dopamine.