Effects of Intravenous anesthetics on Phosphatidylinositol Response of Spinal Descending Inhibitory Pathways of Rat

去甲肾上腺素能神经元起源于蓝斑，广泛投射至脊髓、大脑皮质等。脊髓中的去甲肾上腺素能通路被认为是对脊髓感觉传递的中枢下行抑制作用之一。中枢神经系统中的去甲肾上腺素（NE）通过肾上腺素能受体刺激磷脂酰肌醇（PI）反应。本研究旨在观察静脉麻醉药对NE诱导的大鼠脊髓PI反应的影响。材料与方法：实验选用雄性Wistar大鼠，体重250-350 g。戊巴比妥钠麻醉后，快速分离胸段脊髓。将脊髓切成1 mm宽的切片。将三片切片置于小平底管中，并在含有5 mM LiCl的K-H溶液中孵育。观察了静脉麻醉药对NE诱导的磷酸肌醇（IP_1）蓄积的影响。用液体闪烁计数器测定了[^3H]肌醇孵育的脊髓片[^3H]IP_1。结果如下：氟哌利多能剂量依赖性地抑制NE诱导的脊髓片IP_1蓄积，而氯胺酮、芬太尼和咪达唑仑则不能抑制NE诱导的IP_1蓄积。

Noradrenergic neurons arise from the locus coeruleus and project widely to the spinal cord, cerebral cortex andothers. Noradrenergic pathways in the spinal cord are considered to be one of the central descending inhibitory influences on spinal sensory transmission. Norepinephrine (NE) in the central nervous system has the effect to stimulate phosphatidylinositol (PI) response through aradrenergic receptors. The present study was designed to examine the effects of intravenous anesthetics on NE-induced PI response of rat spinal cords. Materials and Methods: Male Wistar ratsweighing 250-350 g were used for the experiments. , The rats were anesthetized with pentobarbital and their thoracic spinal cord was rapidly isolated. The spinal cord waschopped into 1-mm-wide slices. Three pieces of the slice were placed in small flat-bottomed tubes andincubated in K-H solution containing 5 mM LiCI. The effects of intravenous anesthetics on NE-induced inositol monophosphate (IP_1) accumulation were examined. We measured [^3H]IP_1 in spinal cord slices incubated with [^3H]myo-inositol with aliquid scintillation counter. Results : NE-induced IP_1 accumulation of spinal cord slices was attenuated dose-dependently by droperidol, but was not attenuated by ketamine, fentanyl and midazolam.