Acutain Maria Florencia, Griebler Luft Jordana, Vazquez Cecila Alejandra, Popik Bruno, Cercato Magalí C, Epstein Alberto, Salvetti Anna, Jerusalinsky Diana A, de Oliveira Alvares Lucas, Baez Maria Verónica
Instituto de Biología Celular y Neurociencia "Prof. E. De Robertis" (IBCN, CONICET-UBA), Buenos Aires, Argentina.
Instituto de Biociências, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil.
Front Neurosci. 2021 Apr 9;15:644100. doi: 10.3389/fnins.2021.644100. eCollection 2021.
-methyl-D-aspartate receptors are heterotetramers composed of two GluN1 obligatory subunits and two regulatory subunits. In cognitive-related brain structures, GluN2A and GluN2B are the most abundant regulatory subunits, and their expression is subjected to tight regulation. During development, GluN2B expression is characteristic of immature synapses, whereas GluN2A is present in mature ones. This change in expression induces a shift in GluN2A/GluN2B ratio known as developmental switch. Moreover, modifications in this relationship have been associated with learning and memory, as well as different pathologies. In this work, we used a specific shRNA to induce a reduction in GluN2A expression after the developmental switch, both in primary cultured hippocampal neurons and in adult male Wistar rats. After characterization, we performed a cognitive profile and evaluated seizure susceptibility . Our results showed that the decrease in the expression of GluN2A changes GluN2A/GluN2B ratio without altering the expression of other regulatory subunits. Moreover, rats expressing the anti-GluN2A shRNA displayed an impaired contextual fear-conditioning memory. In addition, these animals showed increased seizure susceptibility, in terms of both time and intensity, which led us to conclude that deregulation in GluN2A expression at the hippocampus is associated with seizure susceptibility and learning-memory mechanisms.
N-甲基-D-天冬氨酸受体是由两个必需的GluN1亚基和两个调节亚基组成的异源四聚体。在与认知相关的脑结构中，GluN2A和GluN2B是最丰富的调节亚基，它们的表达受到严格调控。在发育过程中，GluN2B的表达是未成熟突触的特征，而GluN2A存在于成熟突触中。这种表达变化会导致GluN2A/GluN2B比率发生转变，即发育转换。此外，这种关系的改变与学习和记忆以及不同的病理状况有关。在这项研究中，我们使用一种特异性短发夹RNA（shRNA），在发育转换后，在原代培养的海马神经元和成年雄性Wistar大鼠中诱导GluN2A表达降低。在进行表征后，我们进行了认知分析并评估了癫痫易感性。我们的结果表明，GluN2A表达的降低改变了GluN2A/GluN2B比率，而没有改变其他调节亚基的表达。此外，表达抗GluN2A shRNA的大鼠表现出情境恐惧条件记忆受损。此外，这些动物在发作时间和强度方面均表现出癫痫易感性增加，这使我们得出结论，海马中GluN2A表达失调与癫痫易感性和学习记忆机制有关。
