Department of Pharmacology, Kyung Hee University School of Medicine, Seoul, South Korea.
Doctorado en Ciencias Biologicas, Universidad Autonoma de Tlaxcala, Tlax, Mexico.
Sci Rep. 2019 Nov 5;9(1):15981. doi: 10.1038/s41598-019-52413-0.
The Na/HCO cotransporter NBCn1/SLC4A7 can affect glutamate neurotoxicity in primary cultures of rat hippocampal neurons. Here, we examined NMDA-induced neurotoxicity in NBCn1 knockout mice to determine whether a similar effect also occurs in the mouse brain. In primary cultures of hippocampal neurons from knockouts, NMDA had no neurotoxic effects, determined by lactate dehydrogenase release and nitric oxide synthase (NOS)-dependent cGMP production. Male knockouts and wildtypes (6-8 weeks old) were then injected with NMDA (75 mg/kg; ip) and hippocampal neuronal damages were assessed. Wildtypes developed severe tonic-clonic seizures, whereas knockouts had mild seizure activity (motionless). In knockouts, the NOS activity, caspase-3 expression/activity and the number of TUNEL-positive cells were significantly low. Immunochemical analysis revealed decreased expression levels of the NMDA receptor subunit GluN1 and the postsynaptic density protein PSD-95 in knockouts. Extracellular recording from hippocampal slices showed no Mg/NMDA-mediated epileptiform events in knockouts. In conclusion, these results show a decrease in NMDA neurotoxicity by NBCn1 deletion. Given that acid extrusion has been known to prevent pH decrease and protect neurons from acid-induced damage, our study presents novel evidence that acid extrusion by NBCn1 stimulates neurotoxicity.
钠/碳酸氢根共转运蛋白 NBCn1/SLC4A7 可影响原代培养的大鼠海马神经元中的谷氨酸神经毒性。在这里，我们研究了 NBCn1 敲除小鼠中的 NMDA 诱导的神经毒性，以确定这种类似的效应是否也发生在小鼠大脑中。在 NBCn1 敲除的海马神经元原代培养物中，NMDA 没有神经毒性作用，这是通过乳酸脱氢酶释放和一氧化氮合酶（NOS）依赖性 cGMP 产生来确定的。然后，雄性敲除和野生型（6-8 周龄）小鼠被注射 NMDA（75mg/kg；ip），并评估海马神经元损伤。野生型小鼠发展为严重的强直-阵挛性癫痫发作，而敲除型小鼠仅有轻度的癫痫活动（不动）。在敲除型小鼠中，NOS 活性、caspase-3 表达/活性和 TUNEL 阳性细胞数量明显降低。免疫化学分析显示，敲除型小鼠中 NMDA 受体亚基 GluN1 和突触后密度蛋白 PSD-95 的表达水平降低。从海马切片进行的细胞外记录显示，敲除型小鼠中没有 Mg/NMDA 介导的癫痫样事件。总之，这些结果表明 NBCn1 缺失可降低 NMDA 神经毒性。鉴于已知酸外排可防止 pH 值下降并保护神经元免受酸诱导的损伤，我们的研究提供了新的证据，表明 NBCn1 的酸外排刺激了神经毒性。
