Protective effect of nicotine through nicotinic acetylcholine receptor alpha 7 on hypoxia-induced membrane disintegration and DNA fragmentation of cultured PC12 cells.
To investigate the effect of nicotine on hypoxic neuronal damage, cultured PC12 cells were exposed to hypoxia for 9 h and then reoxygenated for 72 h. The cells were stained by propidium iodide (PI), a marker of cell membrane disintegration and the TUNEL method, which indicates DNA fragmentation. In control cultures, the ratio of PI-positive cells to total cells progressively increased during and after exposure to hypoxia, constituting 39% of total cells at 72 h posthypoxia. This increase in PI-positive cells was completely inhibited by nicotine until 12 h posthypoxia, and was partially and dose-dependently inhibited thereafter. The ratio of TUNEL-positive cells to total cells started to increase at 24 h posthypoxia and reached 36% at 72 h in control cultures. This ratio was also dose-dependently inhibited by nicotine. These inhibitory effects of nicotine on the increase in PI-positive and TUNEL-positive cells were abolished by the addition to the medium of alpha-bungarotoxin, an antagonistic ligand for nicotinic acetylcholine receptor (AChR) alpha7. These findings suggest that nicotine inhibits, through AChR alpha7, hypoxia-induced cell membrane disintegration and DNA fragmentation of cultured PC12 cells exposed to hypoxia.
Tohgi
H
H
Department of Neurology, Iwate Medical University, Uchimaru 19-1, Morioka, Iwate, Japan.
Utsugisawa
K
K
Nagane
Y
Y
D000818:Animals; D002038:Bungarotoxins / Q000502:physiology*; D015687:Cell Hypoxia / Q000187:drug effects / Q000502:physiology; D002460:Cell Line; D002462:Cell Membrane / Q000187:drug effects / Q000502:physiology; D053938:DNA Fragmentation / Q000187:drug effects / Q000502:physiology*; D020287:In Situ Nick-End Labeling; D009538:Nicotine / Q000494:pharmacology*; D016716:PC12 Cells / Q000187:drug effects / Q000502:physiology*; D051381:Rats; D011978:Receptors, Nicotinic / Q000502:physiology*; D064569:alpha7 Nicotinic Acetylcholine Receptor
D002038:Bungarotoxins; C579165:Chrna7 protein, rat; D011978:Receptors, Nicotinic; D064569:alpha7 Nicotinic Acetylcholine Receptor; D009538:Nicotine