Epileptogenesis in organotypic hippocampal cultures has limited dependence on culture medium composition

Rodent organotypic hippocampal cultures spontaneously develop epileptiform activity after approximately 2 weeks in vitro and are increasingly used as a model of chronic post-traumatic epilepsy. However, organotypic cultures are maintained in an artificial environment (culture medium), which contains electrolytes, glucose, amino acids and other components that are not present at the same concentrations in cerebrospinal fluid (CSF). Therefore, it is possible that epileptogenesis in organotypic cultures is driven by these components. We examined the influence of medium composition on epileptogenesis. Epileptogenesis was evaluated by measurements of lactate and lactate dehydrogenase (LDH) levels (biomarkers of ictal activity and cell death, respectively) in spent culture media, immunohistochemistry and automated 3-D cell counts, and extracellular recordings from CA3 regions. Changes in culture medium components moderately influenced lactate and LDH levels as well as electrographic seizure burden and cell death. However, epileptogenesis occurred in any culture medium that was capable of supporting neural survival. We conclude that medium composition is unlikely to be the cause of epileptogenesis in the organotypic hippocampal culture model of chronic post-traumatic epilepsy.

啮齿类器官型海马培养物在体外培养约2周后可自发产生癫痫样活动，该模型正日益被用作慢性创伤后癫痫的研究模型。然而，器官型培养物需维持于人工培养基环境中，此类培养基所含的电解质、葡萄糖、氨基酸及其他组分的浓度与脑脊液（CSF）中的浓度并不一致。因此，器官型培养物中的致痫过程可能由这些组分驱动。我们探究了培养基组成对致痫过程的影响：通过检测废弃培养基中的乳酸与乳酸脱氢酶（LDH）水平（分别为发作活动与细胞死亡的生物标志物）、免疫组织化学与自动化三维细胞计数，以及CA3区的细胞外记录来评估致痫情况。结果显示，培养基组分的变化会适度影响乳酸与LDH水平，同时也会影响脑电图样癫痫负荷与细胞死亡程度，但只要培养基能够支持神经元存活，无论其组成如何，均会发生致痫过程。据此我们认为，在慢性创伤后癫痫的器官型海马培养模型中，培养基组成不太可能是致痫过程的诱因。