Dringenberg H C, Vanderwolf C H
Neuroscience Program, University of Western Ontario, London, Canada.
Brain Res Bull. 1995;36(3):285-92. doi: 10.1016/0361-9230(94)00204-e.
In urethane-anesthetized rats, neocortical LVFA induced by 100 Hz electrical stimulation of the median raphe area or by tail pinching was completely eliminated by a combination of scopolamine (5 mg/kg, IP) and p-chlorophenylalanine (500 mg/kg/day x 3, IP), providing evidence that LVFA is dependent on cholinergic-muscarinic and serotonergic inputs to the neocortex in urethane-anesthetized as well as in freely moving rats. The serotonergic receptor antagonists ketanserin and methiothepin (1-10 mg/kg, IP) also produced a dose-dependent blockade of LVFA in urethane-anesthetized rats, and eliminated virtually all LVFA when combined with scopolamine. A combination of diethyl ether anesthesia and scopolamine completely eliminated all neocortical LVFA without additional antiserotonergic treatment, and a combination of chloral hydrate anesthesia and scopolamine similarly blocked all LVFA in about 50% of the rats tested. In the remaining chloral hydrate-anesthetized rats, the residual LVFA could be eliminated by the serotonergic antagonist ritanserin (10 mg/kg, IP). As shown previously, in nonanesthetized rats treated with scopolamine, LVFA can be maintained by a serotonergic input to the neocortex. The present data suggest that some general anesthetics reduce or completely abolish this serotonergic LVFA. Further, the serotonergic antagonists used here exert much stronger antiserotonergic effects in rats anesthetized with urethane or chloral hydrate than in freely moving rats. Therefore, studies of serotonergic transmission or antagonist action, especially in the neocortex, in anesthetized rats may not be applicable to the waking state.
在氨基甲酸乙酯麻醉的大鼠中，通过对中缝核区域进行100 Hz电刺激或夹尾诱导的新皮质低频场活动（LVFA），可被东莨菪碱（5 mg/kg，腹腔注射）和对氯苯丙氨酸（500 mg/kg/天×3，腹腔注射）联合用药完全消除，这表明在氨基甲酸乙酯麻醉的以及自由活动的大鼠中，LVFA依赖于向新皮质的胆碱能 - 毒蕈碱能和5-羟色胺能输入。5-羟色胺能受体拮抗剂酮色林和甲硫噻平（1 - 10 mg/kg，腹腔注射）在氨基甲酸乙酯麻醉的大鼠中也产生了剂量依赖性的LVFA阻断作用，并且与东莨菪碱联合使用时几乎消除了所有LVFA。乙醚麻醉和东莨菪碱联合用药可完全消除所有新皮质LVFA，无需额外的抗5-羟色胺能治疗，水合氯醛麻醉和东莨菪碱联合用药在约50%的受试大鼠中同样阻断了所有LVFA。在其余水合氯醛麻醉的大鼠中，残余的LVFA可被5-羟色胺能拮抗剂利坦色林（10 mg/kg，腹腔注射）消除。如先前所示，在用东莨菪碱治疗的未麻醉大鼠中，LVFA可通过向新皮质的5-羟色胺能输入得以维持。目前的数据表明，一些全身麻醉剂可降低或完全消除这种5-羟色胺能LVFA。此外，此处使用的5-羟色胺能拮抗剂在氨基甲酸乙酯或水合氯醛麻醉的大鼠中比在自由活动的大鼠中发挥更强的抗5-羟色胺能作用。因此，对麻醉大鼠中5-羟色胺能传递或拮抗剂作用的研究，尤其是在新皮质中的研究，可能不适用于清醒状态。
