Objective To analyze the expression changes of placental growth factor(PLGF) in neonatal rats with hypoxic-ischemic brain damage,and to discuss the possible roles of PLGF in alleviating cerebral ischemia,promoting regeneration of blood vessels as well as the protective effects of Shenfu injection on the expression of PLGF. Method All the neonatal rats were randomly divided into three groups:sham operation group (S),Shenfu injection treatment group (SF),and saline control group (C).They were further divided into five subgroups(n=8 per subgroup) according to the time points:6 h,12 h,1 d,3 d,7 d.Models of postnatal 7-day Sprague Dawley rats with HIBD were established with Rice methods.Group SF was treated with Shenfu injection (10 mg/kg,ip) immediately after hypoxic-ischemic brain damage (HIBD).The injection lasted for three days once a day at the same time.Group C was treated with saline in the same way with the same dosage.There was no treatment with any drugs in Group S.RT-PCR and immunohistochemistry method were used to detect the changes of PLGF in the lesion side cerebral cortex in neonatal rats. Results Expression of PLGF in group S was the same at different time points(P>0.05); In group C,the expression of PLGF started to increase at 6 h,and reached a peak at 1 d and then gradually declined.The expression level was higher than S group from 12 h to 7 d(P<0.05);In SF group,the expression increased before 6 h,and the tendency of expression was similar to C group;However it had a more obvious decline at 3 d.The whole level was apparently higher than S and C groups. Conclusion The expression levels of PLGF increase highly after hypoxic-ischemic brain damage,and Shenfu injection can protect the brain from damage effectively through facilitating the expression of PLGF.