Changes in endoplasmic reticulum Ca(2-)-ATPase mRNA levels in transient cerebral ischemia of rat: a quantitative polymerase chain reaction study

Transient cerebral ischemia was produced in rats using the four-vessel occlusion model. After 30 min ischemia and 2, 4, 8, or 24 h of recirculation, total RNA was isolated from the cortex, striatum and hippocampus and reverse transcribed into cDNA. Endoplasmic reticulum (ER) calcium-ATPase (SERCA, subunit 2b) cDNA was amplified using appropriate primers. Ischemia-induced changes in SERCA mRNA levels were analyzed by quantitative polymerase chain reaction (PCR). For quantification, each PCR reaction was run in the presence of an internal standard. In control brains SERCA mRNA levels amounted to 392 +/- 43,431 +/- 86, and 409 +/- 21 micrograms mRNA/g total RNA in the cortex, striatum and hippocampus, respectively. SERCA mRNA levels did not change significantly during the first 8 h of recovery. After 24 h of recovery, however, SERCA mRNA levels decreased sharply in the hippocampus and striatum (P < 0.001 versus control) but not in the cortex. It is concluded that in vulnerable brain structures a post-ischemic disturbance in ER calcium homeostasis may limit the recovery of neurons from metabolic stress.