Alpha7 nicotinic ACh receptor mediated neuroprotective action by nicotine and GTS-21: An approach by the hippocampal organotypic slice cultures.

Nicotine, main constituent of tabaco, is known as a nicotinic acetylcholine receptor (nAChR) agonist and increases cognitive performance. 3-(2,4-dimethoxybenzylidene)-anabaseine (GTS-21) is derived from the marine worm toxin, anabaseine, and is alpha7-selective nAChR (Δ 7-nAChR) agonist. Both nicotine and GTS-21 were expected as therapeutic agents of Alzheimer’s disease. Several studies showed that nicotine and GTS-21 protected neuron by activating nAChR, especially Δ 7-nAChR. It has been reported that Δ 7-nAChR has been shown to be an essential regulator of inflammation. The purpose of this study is to examine the neuroprotective and anti-inflammatory effects of nicotine and GTS-21 using organotypic hippocampal slice cultures. Kainic acid (KA, 5-50 �� M) induced concentration- and time-dependent neuronal cell death in the hippocampal organotypic slice cultures. The pretreatment with nicotine and GTS-21 tended to decrease in KA toxicity. In a CA3 area-specific analysis, pretreatment with nicotine resulted in significant inhibition of KA-induced neurotoxicity. The results suggest that nicotine may protect KA-induced neuronal cell death via Δ 7-nAChR. We also examined anti-inflammatory effects of nicotine and GTS-21. Hippocampal slices were pretreated with nicotine or GTS-21, and then treated with lipopolysaccharide (LPS). LPS