Abstract: Objective To investigate the changes of endoplasmic reticulum stress (ERS)- and apoptosis-related factors in rat
cerebral cortex following controlled hypotension. Methods Twenty-four healthy male SD rats were randomly divided into 4
equal groups, including a sham hypotension group (group A) and 3 hypotension groups with the mean arterial pressure
maintained for 60 min at 70 mmHg (group B), 50 mmHg (group) and 30 mmHg (group D) with sodium nitroprusside and
esmolol. All the rats received an equal volume of fluid infusion. Twelve hours after controlled hypotension, the rats were
sacrificed to examine the protein expressions of Bax, Bcl-2, glucose-regulated protein 78 (GRP78), C/EBP homologous protein
(CHOP) and caspase-12 in the cortex with Western blotting. GRP78 mRNA expression was measured by RT-PCR, and the cell
apoptosis was evaluated by TUNEL staining. Results Compared with those in group A, GRP78 mRNA and protein
expressions of GRP78, CHOP, caspase-12 related with ERS increased significantly in groups C and D (P<0.05), especially in
group D (P<0.05), but not in group B (P>0.05). Apoptotic cells and Bax expression increased and Bcl-2 expression decreased
significantly in groups C and D (P<0.05), but not in group B (P>0.05); such changes were more prominent in group D than in
group C (P<0.05). Conclusion Mild controlled hypotension (70 mmHg) does not induce neuronal injury in rat cerebral cortex,
but severe hypertension (lower than 50 mmHg) can cause neuronal ERS and apoptosis.