In Parkinson disease, which region of the brain shows the earliest and most severe loss of dopaminergic neurons, and what are the intraeuronal protein aggregates called?
- A Substantia nigra pars compacta; Lewy bodies (alpha-synuclein aggregates) ✓
- B Striatum (caudate and putamen); Negri bodies
- C Locus coeruleus; Pick bodies (tau aggregates)
- D Subthalamic nucleus; neurofibrillary tangles (tau/Abeta)
Correct answer: A. Substantia nigra pars compacta; Lewy bodies (alpha-synuclein aggregates)
Explanation
Parkinson disease is characterized by selective degeneration of dopaminergic neurons in the substantia nigra pars compacta (SNpc), leading to dopamine depletion in the striatum and the clinical motor features (tremor, rigidity, bradykinesia). Surviving neurons contain Lewy bodies — eosinophilic intracytoplasmic inclusions composed of aggregated alpha-synuclein (along with ubiquitin and neurofilaments). The progressive Braak staging scheme indicates that alpha-synuclein pathology actually begins in the olfactory bulb and dorsal vagal nucleus before the SNpc.
Reference: Robbins & Cotran Pathologic Basis of Disease, 10th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.