Calbindin-D_28K-containing neurons in animal models of neurodegeneration: possible protection from excitotoxicity

Brain levels of the calcium binding protein Calbindin-D_28K (CaBP_28K) and CaBP_28K mRNA were measured for various animal models of neurodegenerative diseases (MPTP-treated C57BL/6J mice and Sprague-Dawley rats receiving striatal/intraperitoneal kainic acid or quinolinic acid into the nucleus basalis magnocellularis). Brain areas were tested (radioimmunoassay, Western blot, slot blot, and Northern blot) for levels of CaBP_28K and CaBP_28K mRNA. The various models did not exhibit any changes in protein or mRNA levels from the controls, suggesting that CaBP_28K-containing neurons were not lost after exposure to these neurotoxins. Immunocytochemical characterization of the substantia nigra of the MPTP-treated mice revealed that there was significant dopaminergic cell loss in this brain area after MPTP treatment. The majority of dopaminergic neurons that degenerated did not contain CaBP_28K. The small percentage of surviving neurons were CaBP_28K-positive. These results suggest that the presence of CaBP_28K may protect neurons from calcium-mediated neurotoxicity.