Zheng Qi-Hui, Li Guo-Cai, Cheng Jing, Fang Fang, Wu Zhong-Hai
Department of Physiology, Southern Medical University, Guangzhou, China.
Sheng Li Xue Bao. 2011 Jun 25;63(3):233-7.
The study aims to identify the role of cAMP-PKA pathway in the group Ⅱ metabotropic glutamate receptors (mGluRs)-mediated regulation of respiratory rhythm from the brainstem slice. Neonatal (aged 0-3 d) Sprague-Dawley rats of either sex were used. The brainstem slice containing the medial region of the nucleus retrofacialis (mNRF) and the hypoglossal nerve rootlets was prepared, and the surgical procedure was performed in the modified Kreb's solution (MKS) with continuous carbogen (95% O2 and 5% CO2) bubbling, and ended in 3 min. Respiratory rhythmical discharge activity (RRDA) of the hypoglossal nerve rootlets was recorded by suction electrode. Eighteen brainstem slice preparations were divided into 3 groups. In group 1, group Ⅱ mGluRs specific antagonist (2S)-α-ethylglutamic acid (EGLU) was added into the perfusion solution for 10 min. In group 2, after application of Forskolin for 10 min, washout with MKS, the slice was perfused with Rp-cyclic 3', 5'-hydrogen phosphorothioate adenosine triethylammonium salt (Rp-cAMPS) alone for another 10 min. In group 3, after application of Rp-cAMPS for 10 min, additional EGLU was added into the perfusion for another 10 min. The results showed EGLU shortened respiratory cycle (RC), but the changes of integral amplitude (IA) and inspiratory time (TI) were not statistically significant. Forskolin induced significant decreases in RC, and increased TI, IA. Rp-cAMPS could make the opposite effect compared with the changes of RRDA with Forskolin. The effect of EGLU on the RRDA was inhibited after blocking the cAMP-PKA pathway. Taken together, cAMP-PKA pathway may play an important role in the group Ⅱ mGluRs-mediated regulation of RRDA in the brainstem slice of neonatal rats.
本研究旨在从脑干切片中确定环磷酸腺苷-蛋白激酶A（cAMP-PKA）信号通路在Ⅱ型代谢型谷氨酸受体（mGluRs）介导的呼吸节律调节中的作用。选用新生（0-3日龄）的Sprague-Dawley大鼠，雌雄不限。制备包含面神经后核内侧区域（mNRF）和舌下神经根的脑干切片，手术操作在改良的克雷布斯溶液（MKS）中进行，持续通入混合气体（95% O₂和5% CO₂），3分钟内完成。用吸引电极记录舌下神经根的呼吸节律性放电活动（RRDA）。18个脑干切片标本分为3组。第1组，在灌注液中加入Ⅱ型mGluRs特异性拮抗剂（2S）-α-乙基谷氨酸（EGLU）10分钟。第2组，用福司可林处理10分钟后，用MKS冲洗，然后仅用Rp-环磷腺苷3',5'-硫代磷酸三乙铵盐（Rp-cAMPS）灌注切片10分钟。第3组，用Rp-cAMPS处理10分钟后，在灌注液中再加入EGLU 10分钟。结果显示，EGLU缩短了呼吸周期（RC），但积分幅度（IA）和吸气时间（TI）的变化无统计学意义。福司可林使RC显著缩短，TI和IA增加。与福司可林引起的RRDA变化相比，Rp-cAMPS产生相反的作用。阻断cAMP-PKA信号通路后，EGLU对RRDA的作用受到抑制。综上所述，cAMP-PKA信号通路可能在新生大鼠脑干切片中Ⅱ型mGluRs介导的RRDA调节中起重要作用。
