Does the calcium binding protein calretinin protect dopaminergic neurons against degeneration in Parkinsons disease?
Parkinson’s disease (PD) is characterized by a heterogeneous loss of dopaminergic neurons in the human mesencephalon affecting mainly the substantia nigra pars compacta (SNpc) and to a lesser extent the other dopaminergic cell groups. A rise in intracellular calcium concentrations represents one of the final events leading to nerve cell death. Calbindin D28k, a protein capable of buffering intracellular calcium concentrations is present in the dopaminergic neurons that are selectively preserved in PD but not in those that degenerate. To determine whether other calcium-binding proteins also represent putative protective factors of dopaminergic neurons in PD, we analyzed immunohistochemically the distribution of calretinin-containing (CR+) neurons, in the human mesencephalon of three control subjects and four patients with PD. No significant differences were observed between the number of CR+ neurons in the two subject groups. Sequential double immunostaining for calretinin and tyrosine
