To explore the effects of tanshinolon on Rho/ROCK signaling pathway in brain nerve cells and brain tissues of IUGR fetal rats. Methods:A total of 40 pregnant rats were randomly divided into a normal group, a IUGR group, a IUGR+ low-dose, a medium-dose and a high-dose tanshinol group. The IUGR model was established by low-protein diet. Normal group and IUGR group were injected with 5.0 mg/kg saline intravenously on the 12th day of pregnancy. Low, medium and high dose groups of tanshinolon were injected with tanshinol solution with equal volume and different concentration intravenously from the 12th day of pregnancy, respectively, with low dose group 10 μ g/(kg·d), medium dose group 20 μ g/(kg·d) and high dose group 30 μ g/(kg·d). The weight of fetal rats was measured within 6 h after natural delivery. After anesthesia, the brain tissue was stained with HE. The expressions of RhoA and ROCKⅡmRNA and protein were determined by RT-PCR and Western blot, and the apoptosis rate of brain nerve cells was detected by flow cytometry. Results:The body weight of fetal rats in IUGR group was significantly lower than that in normal group. The body weight of fetal rats in IUGR+tanshinolhigh-dose group was higher than that in medium dose group and low-dose group (P<0.05). The expression of RhoA, rock Ⅱ mRNA, protein and apoptosis rate of brain nerve cells in IUGR group were higher than those in normal group, while those in IUGR+tanshinol high-dose group were lower than those in middle dose group and low-dose group (P<0.05). Conclusion:Tanshinol can regulate Rho/ROCK signaling pathway and inhibit its activity, so as to promote the proliferation and improve the growth and development of IUGR fetal rat brain cells.