Objective  To investigate the effect of different retinoic acid (RA) configurations

all-trans retinoic acid (ATRA) and 9-Cis-RA on apoptosis of PC12 cells after oxygen and glucose-deprivation (OGD) injury

and explore the receptor pathway involved in.   Methods  Cell morphology before and after OGD injury was observed with inverted microscopy

and the apoptotic rate of PC12 cells treated with different concentrations of ATRA and 9-Cis-RA was studied by flow cytometr after OGD injuryy. Finally

LDH release from PC12 cells was measured by ELISA after 4 hours’ RA treatment for degree of membrane damage. There were 9 groups: A (0 μmol/L RA); B (1 μmol/L ATRA); C (1 μmol/L 9-CisRA); D (5 μmol/L ATRA); E (5 μmol/L 9-CisRA); F (10 μmol/L ATRA); G (10 μmol/L 9-CisRA); H (20 μmol/L ATRA); I (20 μmol/L 9-CisRA).   Results  ATRA at a dose of 1 μmol/L had no effect on the apoptosis of PC12 cells after OGD injury

as the cells without RA treatment (P0.05). But the apoptotic rate were significant increasing when the concentration of ATRA was elevated from 5 μmol/L to 20 μmol/L (P0.05). The apoptotic rates in 10 and 20 μmol/L groups were significantly higher than those of the 9-Cis-RA groups with same stimulus concentration (P0.05) and 0 μmol/L group (P0.05). However

the apoptotic rate in 20 μmol/L 9-Cis-RA was lower than that of 0 μmol/L group (P0.05)

but was not significantly. The levels of LDH release of ATRA stimulation groups were significantly increasing from 5 μmol/L with the concentration rising (P0.01)

and were significantly higher than that of control and 9-Cis-RA stimulation groups (P0.05). There was no significant difference in LDH release between 0 μmol/L group

and each 9-Cis-RA group (P0.05).   Conclusion  ATRA improves the apoptosis of PC12 cells after OGD injury through activating retinoic acid receptors (RAR)

while this effect might be inhibited by 9-Cis-RA via retinoid X receptors (RXRs).