Neuroprotection by Nicotine in Mouse Primary Cortical Cultures Involves Activation of Calcineurin and L-Type Calcium Channel Inactivation

Abstract

Regulation of intracellular calcium influences neuronal excitability, synaptic plasticity, gene expression, and neurotoxicity. In this study, we investigated the role of calcium in mechanisms underlying nicotine-mediated neuroprotection from glutamate excitotoxicity. Neuroprotection by nicotine in primary cortical cultures was not seen in knock-out mice lacking the beta2 subunit of the nicotinic acetylcholine receptor (nAChR). Neuroprotection was partially blocked in wild-type cultures by alpha-bungarotoxin, an antagonist of the alpha7 nAChR subtype, suggesting a potential cooperative role for these subtypes. Pretreatment with nicotine decreased glutamate-mediated calcium influx in primary cortical cultures by 41%, an effect that was absent in cultures from knock-out mice lacking the beta2 subunit of the nAChR. This effect was dependent on calcium entry through L-type channels during nicotine pretreatment in wild-type cultures. The ability of nicotine to decrease glutamate-mediated calcium influx was occluded by cotreatment with nifedipine during glutamate application, suggesting that nicotine pretreatment decreased subsequent activity of L-type calcium channels. Treatment with the calcineurin antagonists FK506 and cyclosporine during pretreatment eliminated both nicotine-mediated neuroprotection and the effects of nicotine on L-type channels. We conclude that neuroprotective effects of nicotine in cortical neurons involve both beta2- and alpha7-containing nAChRs, activation of calcineurin, and decreased intracellular calcium via L-type channels.

FK506 prevents mitochondrial-dependent apoptotic cell death induced by 3-nitropropionic acid in rat primary cortical cultures

“…This calcium-dependent phosphatase has been described to be involved in many pathways that ultimately lead to cell death (Asai et al, 1999;Springer et al, 2000). Accordingly, inhibition of calcineurin as a relevant event in FK506-mediated protective effects has been demonstrated by many authors (Ankarcrona et al, 1996;Asai et al, 1999;Mobley and Agrawal, 2003;Nishino et al, 1996;Stevens et al, 2003). However, numerous other studies have excluded a substantial contribution of inhibited calcineurin for neuroprotection exerted by FK506 (Sabatini et al, 1997;Snyder et al, 1998;Toung et al, 1999;Yardin et al, 1998).…”

Nicotinic acetylcholine receptor-mediated calcium signaling in the nervous system

“…These signalling molecules could increase the expression of calcium buffering proteins such as calbindin-D28K, which have been implicated in the nAChR-dependent amelioration of excitotoxic insults [85] . In cortical cultures, the nicotine-induced calcium-dependent activation of the phosphatase calcineurin is proposed to mediate the protection afforded by nicotine against glutamate excitotoxicity [88] .…”

The subtypes of nicotinic acetylcholine receptors on dopaminergic terminals of mouse striatum

“…[15,16], and increases or decreases locomotor activity, depending on dose, species and strain [17,18]. Nicotine treatment also protects animals and neuronal cells in culture from cell death produced by several neurotoxic chemicals [19,20,21,22]. …”

“…For example, nicotine injection enhances several components of learning and memory in rats and mice [11,12,13], decreases anxiety [14] and pain perception [15,16], and increases or decreases locomotor activity, depending on dose, species and strain [17,18]. Nicotine treatment also protects animals and neuronal cells in culture from cell death produced by several neurotoxic chemicals [19,20,21,22].…”