CHANGES IN ENDOPLASMIC-RETICULUM CA2-ATPASE MESSENGER-RNA 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 recirc ulation, total RNA was isolated from the cortex, striatum and hippocam pus and reverse-transcribed into cDNA. Endoplasmic reticulum (ER) calc ium-ATPase (SERCA, subunit 2b) cDNA was amplified using appropriate pr imers. 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 cont rol brains SERCA mRNA levels amounted to 392 +/- 43, 431 +/- 86, and 4 09 +/- 21 mu g mRNA/ g total RNA in the cortex, striatum and hippocamp us, respectively. SERCA mRNA levels did not change significantly durin g the first 8 h of recovery. After 24 h of recovery, however, SERCA mR NA levels decreased sharply in the hippocampus and striatum (P < 0.001 versus control) but not in the cortex. It is concluded that in vulner able brain structures a post-ischemic disturbance in ER calcium homeos tasis may limit the recovery of neurons from metabolic stress.