Activation of nicotinic acetylcholine receptor prevents the production of reactive oxygen species in fibrillar beta amyloid peptide (1-42)-stimulated microglia.
- Author:
Ju Hyun MOON
1
;
Soo Yoon KIM
;
Hwan Goo LEE
;
Seung U KIM
;
Yong Beom LEE
Author Information
- Publication Type:Original Article ; Research Support, Non-U.S. Gov't
- Keywords: acetylcholine; adenosine triphosphate; amyloid beta-protein; microglia; NADPH oxidase; nicotine; reactive oxygen species; receptors, nicotinic; purinoceptor P2Z
- MeSH: Adenosine Triphosphate/analogs & derivatives/metabolism/pharmacology; Amyloid/*metabolism; Amyloid beta-Protein/*pharmacology; Animals; Calcium/metabolism; Enzyme Activation/drug effects; Microglia/cytology/*drug effects/enzymology/*metabolism; NADPH Oxidase/metabolism; Nicotine/pharmacology; Nicotinic Antagonists/pharmacology; Peptide Fragments/*pharmacology; Rats; Rats, Sprague-Dawley; Reactive Oxygen Species/*metabolism; Receptors, Nicotinic/*metabolism; Receptors, Purinergic P2/metabolism
- From:Experimental & Molecular Medicine 2008;40(1):11-18
- CountryRepublic of Korea
- Language:English
- Abstract: Recent studies have reported that the "cholinergic anti-inflammatory pathway" regulates peripheral inflammatory responses via alpha7 nicotinic acetylcholine receptors (alpha7 nAChRs) and that acetylcholine and nicotine regulate the expression of proinflammatory mediators such as TNF-alpha and prostaglandin E2 in microglial cultures. In a previous study we showed that ATP released by beta-amyloid-stimulated microglia induced reactive oxygen species (ROS) production, in a process involving the P2X7 receptor (P2X7R), in an autocrine fashion. These observations led us to investigate whether stimulation by nicotine could regulate fibrillar beta amyloid peptide (1-42) (fA beta(1-42))-induced ROS production by modulating ATP efflux-mediated Ca2+ influx through P2X7R. Nicotine inhibited ROS generation in fA beta(1-42)-stimulated microglial cells, and this inhibition was blocked by mecamylamine, a non-selective nAChR antagonist, and a-bungarotoxin, a selective alpha7 nAChR antagonist. Nicotine inhibited NADPH oxidase activation and completely blocked Ca2+ influx in fA beta(1-42)-stimulated microglia. Moreover, ATP release from fA beta(1-42)-stimulated microglia was significantly suppressed by nicotine treatment. In contrast, nicotine did not inhibit 2',3'-O-(4-benzoyl)-benzoyl ATP (BzATP)-induced Ca2+ influx, but inhibited ROS generation in BzATP-stimulated microglia, indicating an inhibitory effect of nicotine on a signaling process downstream of P2X7R. Taken together, these results suggest that the inhibitory effect of nicotine on ROS production in fA beta(1-42)-stimulated microglia is mediated by indirect blockage of ATP release and by directly altering the signaling process downstream from P2X7R.
