View source for WBR0587

{{WBRQuestion
|QuestionAuthor={{Rim}}
|ExamType=USMLE Step 1
|MainCategory=Physiology
|MainCategory=Physiology
|MainCategory=Physiology
|MainCategory=Physiology
|MainCategory=Physiology
|MainCategory=Physiology
|MainCategory=Physiology
|MainCategory=Physiology
|MainCategory=Physiology
|MainCategory=Physiology
|Prompt=A 25 year old male student is brought to the emergency department by his girlfriend after she noticed he was acting very unusually and complaining of severe chest pain. On admission, his heart rate is 121bpm, blood pressure 152/88 and temperature 38.4 C. On exam, the patient is shaking and sweating profusely, his pupils are markedly dilated and poorly responsive to light with mild nystagmus noted. The resident suspects intravenous drug use after he finds track marks over both upper extremities. A urine toxicology screen is positive. On which of the following steps in the neurotransmitter cycle does the drug used by this patient exert its effects?


[[Image:Synapse_q.jpg|600px]]
|Explanation=Cocaine is a powerful stimulant drug and one of the most commonly abused substances in the world. Acute cocaine toxicity usually presents with hallucinations and paranoid behavior, nausea, vomiting, chest pain, dyspnea, tremors, fever, tachycardia, mydriasis, nystagmus, and seizures. Physical exam usually reveals track marks, skin puncture wounds, and/or eroded nasal mucosa depending on the route of administration. Cocaine acts by inhibiting reuptake of several neurotransmitters, with the most prominent effect on dopamine and norepinephrine reuptake from the synaptic cleft. This causes an increase in neurotransmitter concentration at the synaptic cleft leading to the classic cocaine associated symptoms. 

Educational objective: Cocaine exerts its effect by inhibiting the reuptake of dopamine and norepinephrine from the synaptic cleft.

References:

Gawin FH. Cocaine addiction: psychology and neurophysiology. Science. 1991;251(5001):1580-6.
|AnswerA=A
|AnswerB=B
|AnswerC=C
|AnswerD=D
|AnswerE=E
|RightAnswer=E
|WBRKeyword=Cocaine, Reuptake inhibitor, Neurotransmitter,
|Approved=No
}}