MPTP (2′-methyl-l, 2, 3, 4′- tetrahydro-carbolines) is a causative factor for
**Core Concept**
MPTP (2'-methyl-l, 2, 3, 4'- tetrahydro-carbolines) is a neurotoxin that selectively targets the dopaminergic neurons in the substantia nigra, a region of the brain responsible for motor control.
**Why the Correct Answer is Right**
MPTP works by inhibiting the enzyme monoamine oxidase B (MAO-B), which is responsible for breaking down dopamine. By inhibiting MAO-B, MPTP increases the concentration of dopamine in the synaptic cleft, but also causes an accumulation of its toxic metabolite, 6-hydroxydopamine. This leads to the degeneration of dopaminergic neurons, resulting in parkinsonian symptoms. The substantia nigra is particularly susceptible to MPTP toxicity due to its high concentration of dopamine and the presence of MAO-B.
**Why Each Wrong Option is Incorrect**
**Option A:** MPTP is not associated with Alzheimer's disease, which is characterized by the accumulation of amyloid beta plaques and tau tangles in the brain.
**Option B:** MPTP does not cause Huntington's disease, which is an autosomal dominant disorder caused by an expansion of CAG repeats in the huntingtin gene.
**Option C:** MPTP is not a causative factor for amyotrophic lateral sclerosis (ALS), which is a neurodegenerative disorder affecting motor neurons.
**Clinical Pearl / High-Yield Fact**
MPTP is a valuable tool in the study of Parkinson's disease, as it can induce parkinsonian symptoms in humans and animals, providing a model for studying the disease's pathophysiology.
**Correct Answer: C. Parkinsonism**