Presence of reactive microglia in monkey substantia nigra years after 1‐methyl‐4‐phenyl‐1,2,3,6‐tetrahydropyridine administration

Abstract

This report describes the presence of reactive microglia, the accumulation of extracellular melanin, and the extensive loss of dopaminergic neurons in the substantia nigra of monkeys administered 1‐methyl‐4‐phenyl‐1,2,3,6‐tetrahydropyridine (MPTP) 5 to 14 years before death. This evidence of chronic neuroinflammation years after MPTP exposure is similar to that previously reported in humans. The monkeys were drug free for at least 3 years before death, indicating that a brief exposure to MPTP had instituted an ongoing inflammatory process. The mechanism is unknown but could have important implications regarding the cause of Parkinson's disease and possible approaches to therapy.