Neuronal-Specific Inhibition of Endoplasmic Reticulum Mg2+/Ca2+ ATPase Ca2+ Uptake in a Mixed Primary Hippocampal Culture Model of Status Epilepticus

• Published in: Brain sciences Vol. 10; no. 7; p. 438
• Main Authors: Deshpande, Laxmikant S., DeLorenzo, Robert J., Churn, Severn B., Parsons, J. Travis
• Format: Journal Article
• Language: English
• Published: Basel MDPI AG 10.07.2020; MDPI
• Subjects: Adenosine triphosphate; Animal models; Ca2-transporting ATPase; Calcium (intracellular); Calcium (reticular); Calcium homeostasis; Calcium influx; Calcium sequestration; Cell culture; Convulsions & seizures; Endoplasmic reticulum; Enzymatic activity; Enzymes; Epilepsy; glia; Hippocampus; Homeostasis; Homogenization; Intracellular; Kinases; Laboratory animals; Magnesium; Neuronal-glial interactions; NMDA; Phenotypes; Physiology; seizure; SERCA; Sucrose; United States > US
• ISSN: 2076-3425; 2076-3425
• DOI: 10.3390/brainsci10070438

Loss of intracellular calcium homeostasis is an established mechanism associated with neuronal dysfunction and status epilepticus. Sequestration of free cytosolic calcium into endoplasmic reticulum by Mg2+/Ca2+ adenosinetriphosphatase (ATPase) is critical for maintenance of intracellular calcium homeostasis. Exposing hippocampal cultures to low-magnesium media is a well-accepted in vitro model of status epilepticus. Using this model, it was shown that endoplasmic reticulum Ca2+ uptake was significantly inhibited in homogenates from cultures demonstrating electrophysiological seizure phenotypes. Calcium uptake was mainly neuronal. However, glial Ca2+ uptake was also significantly inhibited. Viability of neurons exposed to low magnesium was similar to neurons exposed to control solutions. Finally, it was demonstrated that Ca2+ uptake inhibition and intracellular free Ca2+ levels increased in parallel with increasing incubation in low magnesium. The results suggest that inhibition of Mg2+/Ca2+ ATPase-mediated endoplasmic reticulum Ca2+ sequestration contributes to loss of intracellular Ca2+ homeostasis associated with status epilepticus. This study describes for the first time inhibition of endoplasmic reticulum Mg2+/Ca2+ ATPase in a mixed primary hippocampal model of status epilepticus. In combination with animal models of status epilepticus, the cell culture model provides a powerful tool to further elucidate mechanisms that result in inhibition of Mg2+/Ca2+ ATPase and downstream consequences of decreased enzyme activity.