Research report Seizure-induced alterations of plasma membrane calcium ATPase isoforms 1, 2 and 3 mRNA and protein in rat hippocampus

Improper intracellular regulation of the ubiquitous second messenger, calcium, has been linked to several pathological conditions. The . plasma membrane calcium ATPase PMCA is one of the primary systems for translocating calcium from the cytosol to the extracellular . milieu. As an initial assessment of the possible involvement of PMCAs in kainate KA -induced neurodegeneration, we have determined the effect of KA-induced seizures upon PMCA mRNA and protein. In situ hybridization was performed on tissue from adult male Sprague-Dawley rats sacrificed at various time points following i.p. injection of KA. KA altered the expression within the hippocampal subfields for mRNAs of PMCA isoforms 1 and 2. PMCA 1 and 2 mRNAs exhibited hybridization below control levels 12-48 h post-injection within CA1 and CA3. Within the dentate gyrus, PMCA 2 mRNA hybridized below control levels 4 h post-injection, but recovered to control levels by 24 h post-injection. Alterations in combined PMCA protein levels occurred at all time points examined post-injection. These observations provide evidence that KA-induced seizures alter the PMCAs at the mRNA and protein levels, suggesting a possible role for this calcium efflux system in the neuronal degeneration inherent to this paradigm.