INDUCTION OF LONG-TERM OSCILLATIONS IN THE gamma FREQUENCY BAND BY nAChR ACTIVATION IN RAT HIPPOCAMPAL CA3 AREA

摘要

The hippocampal neuronal network oscillation at gamma frequency band (gamma oscillation) is generated by the precise interaction between interneurons and principle cells. gamma oscillation is associated with attention, learning and memory and is impaired in the diseased conditions such as Alzheimer's disease (AD) and schizophrenia. Nicotinic acetylcholine receptor (nAChR) plays an important role in the regulation of hippocampal neurotransmission and network activity. It is not known whether nicotine modulates plasticity of network activity at gamma oscillations in the hippocampus. In this study we investigated the effects of nicotine on the long-term changes of KA-induced gamma oscillations. We found that hippocampal gamma oscillations can be enhanced by a low concentration of nicotine (1 mu M), such an enhancement lasts for hours after washing out of nicotine, suggesting a form of synaptic plasticity, named as long-term oscillation at gamma frequency band (LTO gamma). Nicotine-induced LTO gamma was mimicked by the selective alpha 4 beta 2 but not by alpha 7 nAChR agonist and was involved in N-methyl-D-aspartate (NMDA) receptor activation as well as depended on excitatory and inhibitory neurotransmission. Our results indicate that nAChR activation induced plasticity in gamma oscillation, which may be beneficial for the improvement of cognitive deficiency in AD and schizophrenia. (C) 2015 IBRO. Published by Elsevier Ltd. All rights reserved.