Caruana Douglas A, Reed Sean J, Sliz Diane J, Chapman C Andrew
Center for Studies in Behavioral Neurobiology, Department of Psychology, Concordia University, 7141 Sherbrooke Street West, Rm.SP-244, Montréal, Que. H4B 1R6, Canada.
Neurosci Lett. 2007 Oct 9;426(1):6-11. doi: 10.1016/j.neulet.2007.08.025. Epub 2007 Aug 19.
Synaptic plasticity in olfactory inputs to the lateral entorhinal cortex may result in lasting changes in the processing of olfactory stimuli. Changes in dopaminergic tone can have strong effects on basal evoked synaptic responses in the superficial layers of the entorhinal cortex, and the current study investigated whether dopamine may modulate the induction of long-term potentiation (LTP) and depression (LTD) in piriform cortex inputs to layer II of the lateral entorhinal cortex in awake rats. Groups of animals were pretreated with either saline or the selective dopamine reuptake inhibitor GBR12909 prior to low or high frequency stimulation to induce LTD or LTP. In saline-treated groups, synaptic responses were potentiated to 122.4+/-6.4% of baseline levels following LTP induction, and were reduced to 84.5+/-4.9% following induction of LTD. Changes in synaptic responses were maintained for up to 60min and returned to baseline levels within 24h. In contrast, induction of both LTP and LTD was blocked in rats pretreated with GBR12909. Dopaminergic suppression of synaptic plasticity in the entorhinal cortex may serve to restrain activity-dependent plasticity during reward-relevant behavioral states or during processing of novel stimuli.
嗅觉输入至内嗅皮层的突触可塑性可能导致嗅觉刺激处理过程中的持久变化。多巴胺能张力的改变可对内嗅皮层浅层的基础诱发突触反应产生强烈影响，并且当前研究调查了多巴胺是否可能调节清醒大鼠外侧内嗅皮层II层梨状皮层输入中的长时程增强（LTP）和长时程抑制（LTD）的诱导。在进行低频或高频刺激以诱导LTD或LTP之前，对动物组分别用生理盐水或选择性多巴胺再摄取抑制剂GBR12909进行预处理。在生理盐水处理组中，诱导LTP后突触反应增强至基线水平的122.4±6.4%，诱导LTD后突触反应降低至84.5±4.9%。突触反应的变化持续长达60分钟，并在24小时内恢复至基线水平。相比之下，用GBR12909预处理的大鼠中，LTP和LTD的诱导均被阻断。内嗅皮层中多巴胺能对突触可塑性的抑制可能有助于在与奖励相关的行为状态或新刺激处理过程中抑制活动依赖性可塑性。
