Nimodipine protects dopaminergic neurons against inflammation-mediated degeneration through inhibition of microglial activation

Nimodipine, a calcium channel blocker, has been used mainly in the therapy of cardiovascular diseases. Recently, its indications have been extended experimentally to a wider range of disorders especially some central nervous system (CNS) disorders. In this study, we investigated whether nimodipine is neuroprotective to inflammation-mediated neurodegenerative diseases. Pretreatment with nimodipine reduced the degeneration of dopaminergic (DA) neurons induced by LPS in mesencephalic neuron–glia cultures in a dose-dependent manner. The neuroprotective effect of nimodipine was attributed to the inhibition of microglial activation, since nimodipine significantly inhibited the production of nitric oxide (NO), tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β) and prostaglandin E2 (PGE2) from LPS-stimulated microglia. Moreover, nimodipine was not neuroprotective to 1-methyi-4-phenylpyridinium (MPP+)-induced DA neurotoxicity in the absence of microglia. Mechanistic study showed that nimodipine failed to protect the degeneration of neurons in neuron–glia cultures from mice lacking functional NADPH oxidase (PHOX), a key enzyme for extracellular superoxide production in immune cells. Taken together these results suggest that nimodipine is protective to DA neurodegeneration via inhibiting the microglial-mediated oxidative stress and inflammatory response. Thus, nimodipine may be a potential therapeutic agent for the treatment of inflammation-related neurodegenerative disorders such as Parkinson's disease.