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Nicotine‐induced neuroprotection against N ‐methyl‐ d ‐aspartic acid or β‐amyloid peptide occur through independent mechanisms distinguished by pro‐inflammatory cytokines
Author(s) -
Gahring Lorise C.,
Meyer Erin L.,
Rogers Scott W.
Publication year - 2003
Publication title -
journal of neurochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.75
H-Index - 229
eISSN - 1471-4159
pISSN - 0022-3042
DOI - 10.1046/j.1471-4159.2003.02074.x
Subject(s) - neuroprotection , nicotine , pharmacology , nmda receptor , methyllycaconitine , nicotinic agonist , nicotinic acetylcholine receptor , chemistry , biology , biochemistry , receptor , neuroscience
Nicotine, the causative agent of addiction to tobacco, can also be a neuroprotectant. Nicotine‐induced neuroprotection against different toxins is imparted through pharmacologically distinct neuronal nicotinic acetylcholine receptors (nAChR) where protection against chronic N ‐methyl‐ d ‐aspartic acid (NMDA) exposure is through nAChRα7 but protection against the toxic peptide of amyloid precursor protein, Aβ 25−35 , is through nAChRα4β2. The inflammatory cytokine tumor necrosis factor alpha (TNFα) is also neuroprotective, however, in the presence of nicotine, neuroprotection against NMDA is abolished. The specificity of nicotine–TNFα antagonism was further refined using a mouse transgenic dominant negative of nAChRα7 in which nicotine failed to induce neuroprotection against NMDA and antagonism of TNFα was absent. However, nicotine‐mediated neuroprotection against Aβ 25−35 was unaffected and, therefore, did not require the expression of functional nAChRα7s. The mechanism of TNFα‐mediated neuroprotection and antagonism by nicotine was independent of caspase 8 activation or nuclear factor kappa B translocation in neurons but C6‐ceramide addition to neuronal cultures subsequently exposed to NMDA mimicked the neuroprotective effect of TNFα and, like TNFα, it was antagonized by cotreatment with nicotine. Therefore, the neuroprotective effects of nicotine against differing toxic assaults requires distinct nAChR subtypes and proceeds through intracellular pathways that overlap with similarly different mechanisms initiated by pro‐inflammatory cytokines. These results provide insight into how nicotine imparts neuroprotection and modulates inflammatory responses.