Dopaminergic neurons expressing calbindin in normal and parkinsonian monkeys.

In cynomolgus monkeys, midbrain neurons immunoreactive (IR) for the calcium-binding protein calbindin D-28k (CaBP) occur principally in the dorsal tier of substantia nigra pars compacta (SNc) and in the ventral tegmental area (VTA), and most of these neurons co-express tyrosine hydroxylase (TH). In monkeys rendered parkinsonian (PD) after MPTP injections, CaBP-IR neurons are much less severely affected than TH-IR neurons in SNc and in VTA, and most spared neurons in SNc/VTA display both CaBP and TH immunoreactivity. These results reveal that, in contrast to the situation in other neurodegenerative diseases, CaBP may be used as a marker for a specific neuronal population that is less prone to degeneration in Parkinson's disease.