Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, WA, USA.
Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, WA, USA; Department of Anesthesiology and Pain Medicine, Seattle, WA, USA; Department of Neurology, University of Washington, Seattle, WA, USA.
Br J Anaesth. 2022 Jan;128(1):77-88. doi: 10.1016/j.bja.2021.09.036. Epub 2021 Nov 30.
If anaesthetics cause permanent cognitive deficits in some children, the implications are enormous, but the molecular causes of anaesthetic-induced neurotoxicity, and consequently possible therapies, are still debated. Anaesthetic exposure early in development can be neurotoxic in the invertebrate Caenorhabditis elegans causing endoplasmic reticulum (ER) stress and defects in chemotaxis during adulthood. We screened this model organism for compounds that alleviated neurotoxicity, and then tested these candidates for efficacy in mice.
We screened compounds for alleviation of ER stress induction by isoflurane in C. elegans assayed by induction of a green fluorescent protein (GFP) reporter. Drugs that inhibited ER stress were screened for reduction of the anaesthetic-induced chemotaxis defect. Compounds that alleviated both aspects of neurotoxicity were then blindly tested for the ability to inhibit induction of caspase-3 by isoflurane in P7 mice.
Isoflurane increased ER stress indicated by increased GFP reporter fluorescence (240% increase, P<0.001). Nine compounds reduced induction of ER stress by isoflurane by 90-95% (P<0.001 in all cases). Of these compounds, tetraethylammonium chloride and trehalose also alleviated the isoflurane-induced defect in chemotaxis (trehalose by 44%, P=0.001; tetraethylammonium chloride by 23%, P<0.001). In mouse brain, tetraethylammonium chloride reduced isoflurane-induced caspase staining in the anterior cortical (-54%, P=0.007) and hippocampal regions (-46%, P=0.002).
Tetraethylammonium chloride alleviated isoflurane-induced neurotoxicity in two widely divergent species, raising the likelihood that it may have therapeutic value. In C. elegans, ER stress predicts isoflurane-induced neurotoxicity, but is not its cause.
如果麻醉剂会导致一些儿童出现永久性认知缺陷，那么其影响将是巨大的，但麻醉诱导神经毒性的分子原因，以及相应的可能治疗方法，仍存在争议。在发育早期接触麻醉剂会对无脊椎动物秀丽隐杆线虫造成神经毒性，导致内质网（ER）应激和成年后化学趋性缺陷。我们在该模型生物中筛选了缓解神经毒性的化合物，然后在小鼠中测试了这些候选药物的疗效。
我们通过诱导绿色荧光蛋白（GFP）报告基因来检测异氟烷诱导的秀丽隐杆线虫 ER 应激，从而筛选出缓解 ER 应激的化合物。筛选出抑制 ER 应激的药物，以减少麻醉诱导的化学趋性缺陷。然后，将缓解神经毒性的两个方面的化合物用于盲法测试，以抑制异氟烷在 P7 小鼠中诱导的 caspase-3 。
异氟烷增加了 ER 应激，表现为 GFP 报告荧光增加（增加 240%，P<0.001）。有 9 种化合物将异氟烷诱导的 ER 应激降低了 90-95%（所有情况下 P<0.001）。在这些化合物中，四乙铵和海藻糖也缓解了异氟烷诱导的化学趋性缺陷（海藻糖缓解 44%，P=0.001；四乙铵缓解 23%，P<0.001）。在小鼠大脑中，四乙铵减少了异氟烷诱导的皮质前部（-54%，P=0.007）和海马区（-46%，P=0.002）的 caspase 染色。
四乙铵缓解了两种差异很大的物种中异氟烷诱导的神经毒性，增加了其具有治疗价值的可能性。在秀丽隐杆线虫中，ER 应激预测了异氟烷诱导的神经毒性，但不是其原因。
