Namvar Simin, Fathollahi Yaghoub, Javan Mohammad, Zeraati Maryam, Mohammad-Zadeh Mohammad, Shojaei Amir, Mirnajafi-Zadeh Javad
Department of Physiology, Faculty of Medical Sciences, Tarbiat Modares University, Tehran, Iran.
Cellular and Molecular Research Center, Department of Physiology and Pharmacology, School of Medicine, Sabzevar University of Medical Sciences, Sabzevar, Iran.
J Neurol Sci. 2017 Apr 15;375:450-459. doi: 10.1016/j.jns.2017.02.047. Epub 2017 Feb 22.
G-protein coupled receptors may have a role in mediating the antiepileptogenic effect of low-frequency stimulation (LFS) on kindling acquisition. This effect is accompanied by changes at the intracellular level of cAMP. In the present study, the effect of rolipram as a phosphodiesterase inhibitor on the antiepileptogenic effect of LFS was investigated. Meanwhile, the expression of α- and α-subunit of G proteins and regulators of G-protein signaling (RGS) proteins following LFS application was measured. Male Wistar rats were kindled by perforant path stimulation in a semi-rapid kindling manner (12 stimulations per day) during a period of 6days. Application of LFS (0.1ms pulse duration at 1Hz, 200 pulses, 50-150μA, 5min after termination of daily kindling stimulations) to the perforant path retarded the kindling development and prevented the kindling-induced potentiation and kindling-induced changes in paired pulse indices in the dentate gyrus. Intra-cerebroventricular microinjection of rolipram (0.25μM) partially prevented these LFS effects. Twenty-four hours after the last kindling stimulation, the dentate gyrus was removed and changes in protein expression were measured by Western blotting. There was no significant difference in the expression of α-subunit of G and G proteins in different experimental groups. However, application of LFS during the kindling procedure decreased the expression RGS4 and RGS10 proteins (that reduce the activity of G) and prevented the kindling-induced decrease of RGS2 protein (which reduces the G activity). Therefore, it can be postulated that the G protein signaling pathways may be involved in antiepileptogenetic effect of LFS, and this is why decreasing the cAMP metabolism by rolipram attenuates this effect of LFS.
G蛋白偶联受体可能在介导低频刺激（LFS）对点燃形成的抗癫痫发生作用中发挥作用。这种作用伴随着细胞内cAMP水平的变化。在本研究中，研究了磷酸二酯酶抑制剂咯利普兰对LFS抗癫痫发生作用的影响。同时，检测了施加LFS后G蛋白的α和α亚基以及G蛋白信号调节剂（RGS）蛋白的表达。雄性Wistar大鼠在6天的时间里通过穿通通路刺激以半快速点燃方式（每天12次刺激）进行点燃。在穿通通路施加LFS（1Hz，脉冲持续时间0.1ms，200个脉冲，50 - 150μA，在每日点燃刺激结束后5分钟）可延缓点燃发展，并防止点燃诱导的增强以及齿状回中配对脉冲指数的点燃诱导变化。脑室内微量注射咯利普兰（0.25μM）部分阻止了这些LFS效应。在最后一次点燃刺激后24小时，取出齿状回，通过蛋白质印迹法测量蛋白质表达的变化。不同实验组中G蛋白α亚基的表达没有显著差异。然而，在点燃过程中施加LFS可降低RGS4和RGS10蛋白（降低G活性）的表达，并防止点燃诱导的RGS2蛋白（降低G活性）减少。因此，可以推测G蛋白信号通路可能参与LFS的抗癫痫发生作用，这就是为什么咯利普兰通过降低cAMP代谢会减弱LFS的这种作用。
