Department of Pharmacology, Drug Development and Therapeutics, University of Turku, FIN-20014 Turku, Finland.
Neurochem Int. 2010 Apr;56(5):720-6. doi: 10.1016/j.neuint.2010.02.009. Epub 2010 Feb 16.
Depolarization of cultured mouse cerebellar granule cells with potassium or kainate results in developmentally arrested state that includes down-regulation of GABA(A) receptor alpha1, alpha6 and beta2 subunit expression. These subunits are normally strongly expressed in cerebellar granule cells from second postnatal week throughout the adulthood. In the present study we demonstrate that selective activation of AMPA subtype of glutamate receptors down-regulates alpha1 and alpha6 subunit mRNA expression. Removal of AMPA agonist from culture medium restores expression of these subunits indicating reversibility of the down-regulation. In serum-free culture medium AMPA receptor activation did not down-regulate alpha1 or alpha6 subunit expression. Furthermore, the down-regulation was strongly attenuated when the cells were cultured in the presence of dialysed fetal calf serum. The results indicate that down-regulation of GABA(A) receptor alpha1 and alpha6 subunits by AMPA receptor activation is dependent on the presence of low molecular weight compounds present in fetal calf serum. In order to study mouse cerebellar granule cell maturation and/or regulation of GABA(A) receptor subunit expression in culture, the experiments should be performed in the absence of fetal calf serum.
用钾离子或海人酸使培养的小鼠小脑颗粒细胞去极化会导致发育停滞状态，包括 GABA(A) 受体 α1、α6 和 β2 亚基表达下调。这些亚基在第二周后出生的整个成年期的小脑颗粒细胞中都强烈表达。在本研究中，我们证明了 AMPA 型谷氨酸受体的选择性激活下调了 α1 和 α6 亚基 mRNA 的表达。从培养基中去除 AMPA 激动剂可恢复这些亚基的表达，表明下调是可逆的。在无血清培养基中，AMPA 受体的激活不会下调 α1 或 α6 亚基的表达。此外，当细胞在含有透析胎牛血清的情况下培养时，下调作用被强烈减弱。结果表明，AMPA 受体激活导致 GABA(A) 受体 α1 和 α6 亚基下调依赖于胎牛血清中存在的低分子量化合物。为了研究培养中的小鼠小脑颗粒细胞成熟和/或 GABA(A) 受体亚基表达的调节，实验应在无胎牛血清的情况下进行。
