Alojado M E, Ohta Y, Kemmotsu O
Department of Anesthesiology and Intensive Care, Hokkaido University School of Medicine, Sapporo, Japan.
Anesth Analg. 1994 Aug;79(2):257-60. doi: 10.1213/00000539-199408000-00009.
The dorsal raphe (DR) nucleus is a system of nuclei in the midline of the lower brainstem, which is considered one of the most important nuclei in the modulation of pain in the central nervous system. Central noradrenergic systems play an important role in the control of cardiovascular regulation and pain transmission. Clonidine, an alpha 2-adrenergic agonist is used extensively in anesthesia research. In this study, we evaluated the involvement of clonidine in the activity of DR nucleus and its possible role in pain modulation. Seventy-four neurons within the DR nucleus in the rat brainstem slice preparation were tested using extracellular recording techniques. Application of noradrenaline (NA), 50 mumol/L, induced firing activity in 68 neurons tested (92%). NA produced a regular long-lasting firing activity on the DR neurons. Fifty-six neurons (88%) previously excited by NA were inhibited by clonidine, 20 mumol/L. Clonidine suppressed the firing activity of neurons. The results indicate that the firing of DR neurons was under noradrenergic influence and was inhibited by clonidine, which in turn alters nociception by modifying the central serotonergic system.
中缝背核是位于脑干下部中线的一个核团系统，被认为是中枢神经系统中调节疼痛最重要的核团之一。中枢去甲肾上腺素能系统在心血管调节和疼痛传递的控制中发挥重要作用。可乐定，一种α2肾上腺素能激动剂，在麻醉研究中被广泛使用。在本研究中，我们评估了可乐定在中缝背核活动中的作用及其在疼痛调节中的可能作用。使用细胞外记录技术对大鼠脑干切片制备中的74个中缝背核内的神经元进行了测试。应用50μmol/L的去甲肾上腺素（NA），在68个被测试的神经元（92%）中诱导出放电活动。NA在中缝背核神经元上产生了规则的持久放电活动。先前被NA兴奋的56个神经元（88%）被20μmol/L的可乐定抑制。可乐定抑制了神经元的放电活动。结果表明，中缝背核神经元的放电受去甲肾上腺素能的影响，并被可乐定抑制，而可乐定又通过改变中枢5-羟色胺能系统来改变伤害感受。
