Leszkowicz Emilia, Trojniar Weronika
Department of Animal Physiology, Gdańsk University, Poland.
Acta Neurobiol Exp (Wars). 2005;65(4):373-86. doi: 10.55782/ane-2005-1566.
The pedunculopontine tegmental nucleus (PPN) is one of the reticular generators of the hippocampal theta rhythm. The PPN neuronal circuitry related to theta generation involves its cholinergic, GABA-ergic and glutamatergic components. Here we provide data indicating that the PPN tachykinin system may also be a part of this circuitry. In the experimental model of the tail-pinch elicited hippocampal theta in urethane-anesthetized rats (implanted with bilateral recording electrodes in the stratum moleculare of the upper blade of the dentate gyrus and with injection cannula unilaterally inserted into the PPN) it was found that intra-PPN microinjection of Substance P (SP) and [d-Pro2, d-Phe7, d-Trp9]-Substance P (DPDPDT) caused suppression of the theta and enhancement of the delta activity in the hippocampal EEG. Accordingly, there was approximately a 50% (SP)-70% (DPDPDT) decline of the peak power in the theta frequency range and a decrease by 0.4 Hz in the corresponding peak frequency (DPDPDT only) in both hippocampi. The circuitry through which SP exerts its effect in the PPN can be only hypothetical at present. We suggest SP-evoked activation (either direct or indirect through the glutamatergic inputs) of the GABA interneurons which may tonically inhibit PPN outputs to the other theta-relevant structures.
脚桥被盖核（PPN）是海马θ节律的网状发生器之一。与θ节律产生相关的PPN神经元回路涉及其胆碱能、γ-氨基丁酸能和谷氨酸能成分。在此，我们提供的数据表明，PPN速激肽系统也可能是该回路的一部分。在乌拉坦麻醉大鼠（在齿状回上叶片分子层植入双侧记录电极，单侧将注射套管插入PPN）的夹尾诱发海马θ节律的实验模型中，发现向PPN内微量注射P物质（SP）和[D-脯氨酸2，D-苯丙氨酸7，D-色氨酸9]-P物质（DPDPDT）会导致海马脑电图中θ节律的抑制和δ活动的增强。相应地，两个海马中θ频率范围内的峰值功率下降约50%（SP）-70%（DPDPDT），相应的峰值频率下降0.4 Hz（仅DPDPDT）。目前，SP在PPN中发挥作用的回路只能是推测性的。我们认为，SP诱发GABA中间神经元的激活（直接或通过谷氨酸能输入间接激活），这可能会持续抑制PPN向其他与θ节律相关结构的输出。
