The Involvement of Hypothalamic Sleep Pathways in General Anesthesia: Testing the Hypothesis Using the GABAA Receptor β3N265M Knock-In Mouse
The Involvement of Hypothalamic Sleep Pathways in General Anesthesia: Testing the Hypothesis Using the GABAA Receptor β3N265M Knock-In Mouse
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DOI：
10.1523/jneurosci.4997-08.2009
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发表时间：
2009-02-18
影响因子：
5.3
通讯作者：
Franks, Nicholas P.
中科院分区：
文献类型：
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作者：
Zecharia, Anna Y.;Nelson, Laura E.;Franks, Nicholas P.
GABA(A) 受体已被确定为静脉麻醉异丙酚最重要的单一靶标。然而，对该受体的影响如何转化为意识丧失仍然是个谜。一种可能性是麻醉剂作用于自然睡眠途径。在这里，我们通过探索已知与睡眠有关的三个特定脑核中 GABA 突触电流的麻醉敏感性来检验这一假设。利用全细胞电生理学，我们在野生型小鼠和携带 GABAA 受体 β(3) 亚基 (N265M) 特定突变的小鼠的脑切片中记录了来自结节乳头核 (TMN)、穹窿周区 (Pef) 和蓝斑 (LC) 的 GABA 能 IPSC，这大大降低了它们对异丙酚的敏感性，但不降低对神经类固醇 alphaxalone 的敏感性。我们发现这种体内麻醉敏感性模式反映在下丘脑 TMN 和 Pef 核中，这与它们作为直接麻醉靶点的作用一致。相比之下，LC 的麻醉敏感性不受 β(3)N265M 突变的影响，排除了该细胞核作为异丙酚的主要靶点的可能。为了支持 Pef 中的食欲素能神经元参与异丙酚麻醉的假设，我们进一步证明这些神经元在麻醉过程中被体内 GABA 能药物选择性抑制，并且单独调节 Pef 神经元的活性就可以影响翻正反射的丧失。总体而言，我们的结果支持这样的观点，即异丙酚等 GABA 麻醉剂至少部分通过调节下丘脑睡眠通路发挥作用。
The GABA(A) receptor has been identified as the single most important target for the intravenous anesthetic propofol. How effects at this receptor are then translated into a loss of consciousness, however, remains a mystery. One possibility is that anesthetics act on natural sleep pathways. Here, we test this hypothesis by exploring the anesthetic sensitivities of GABAergic synaptic currents in three specific brain nuclei that are known to be involved in sleep. Using whole-cell electrophysiology, we have recorded GABAergic IPSCs from the tuberomammillary nucleus (TMN), the perifornical area (Pef), and the locus ceruleus (LC) in brain slices from both wild-type mice and mice that carry a specific mutation in the GABAA receptor beta(3) subunit (N265M), which greatly reduces their sensitivity to propofol, but not to the neurosteroid alphaxalone. We find that this in vivo pattern of anesthetic sensitivity is mirrored in the hypothalamic TMN and Pef nuclei, consistent with their role as direct anesthetic targets. In contrast, anesthetic sensitivity in the LC was unaffected by the beta(3)N265M mutation, ruling out this nucleus as a major target for propofol. In support of the hypothesis that orexinergic neurons in the Pef are involved in propofol anesthesia, we further show that these neurons are selectively inhibited by GABAergic drugs in vivo during anesthesia, and that a modulation in the activity of Pef neurons alone can affect loss of righting reflex. Overall, our results support the idea that GABAergic anesthetics such as propofol exert their effects, at least in part, by modulating hypothalamic sleep pathways.