Gozal D, Xue Y D, Simakajornboon N
Department of Pediatrics, Tulane University School of Medicine, New Orleans, LA 70112, USA.
Neurosci Lett. 1999 Mar 5;262(2):93-6. doi: 10.1016/s0304-3940(99)00065-8.
Glutamatergic transmission within the nucleus tractus solitarii (nTS) is critical to full expression of hypoxia-induced cardiorespiratory responses in the rat. To further examine the role of N-methyl-D-aspartate (NMDA) and alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionate (AMPA) glutamate receptors in these responses, double-labeling studies of immunoreactivity for c-Fos protein and either NMDA (NR1) or AMPA (mGluR2/3) receptor expression were conducted in normoxic rats and in hypoxic rats receiving vehicle, MK801, or NBQX. Hypoxia markedly increased c-Fos immunoreactivity within nTS neurons which in the vast majority co-labeled for NMDA. Furthermore, MK801 markedly attenuated such responses. In contrast, co-localization of AMPA and c-Fos occurred in only a small proportion of neurons, and NBQX failed to modify hypoxia-induced c-Fos enhancements. These data suggest a predominant role for NMDA but not for AMPA glutamate receptors in nTS mediated components of the hypoxic response.
孤束核（nTS）内的谷氨酸能传递对于大鼠缺氧诱导的心肺反应的充分表达至关重要。为了进一步研究N-甲基-D-天冬氨酸（NMDA）和α-氨基-3-羟基-5-甲基-4-异恶唑丙酸（AMPA）谷氨酸受体在这些反应中的作用，在常氧大鼠以及接受载体、MK801或NBQX的缺氧大鼠中，进行了c-Fos蛋白免疫反应性与NMDA（NR1）或AMPA（mGluR2/3）受体表达的双重标记研究。缺氧显著增加了nTS神经元内的c-Fos免疫反应性，绝大多数这些神经元同时标记有NMDA。此外，MK801显著减弱了此类反应。相比之下，AMPA和c-Fos的共定位仅发生在一小部分神经元中，并且NBQX未能改变缺氧诱导的c-Fos增强。这些数据表明，在nTS介导的缺氧反应成分中，NMDA谷氨酸受体起主要作用，而AMPA谷氨酸受体不起主要作用。
