NICOTINE-EVOKED NITRIC-OXIDE RELEASE IN THE RAT HIPPOCAMPAL SLICE

The effects of cholinergic agonists on nitric oxide (NO) release in hi ppocampal slices from male Sprague-Dawley rats were investigated using electrochemical recording procedures using Nafion and o-phenylenediam ine-treated carbon fiber microelectrodes. These microelectrodes are hi ghly selective for NO versus other interferents. Acetylcholine (Ach) w ith neostigmine, or nicotine was delivered by pressure ejection from p ipettes placed within 300 mu m of the NO sensors. Both Ach and nicotin e produced NO signals ranging from 0.04 to 2.14 mu M in the CA1, CA3, and dentate gyrus of the rat hippocampus that lasted for 2-5 min. The Ach responses were not antagonized by the muscarinic antagonist atropi ne. However, nicotine-evoked responses were partially antagonized by a lpha-bungarotoxin, a finding consistent with alpha-nicotinic cholinerg ic receptors being involved with the effects of nicotine. These data s upport the hypothesis that nicotine is capable of evoking long lasting NO release in the hippocampus. (C) 1998 Elsevier Science Ireland Ltd. All rights reserved.