Objective To investigate the effects of Taurine on the proliferation of neural stem cells(NSCs) with intrauterine growth restriction(IUGR) in fetal rats and the expressions of Ras homolog gene family member A(RhoA) and Rho-associated coiled-coil containing protein kinase (ROCK) Ⅱ in the process of proliferation.Methods IUGR fetal rats models were established with low protein diet.NSCs from subventricular zone were isolated and cultured in vitro.The NSCs were divided into 5 groups:normal control group(group Ⅰ),IUGR group(group Ⅱ),IUGR + Taurine group (group Ⅲ),IUGR + ROCK blockers group(group Ⅳ),IUGR + Taurine + ROCK blockers group(group Ⅴ).The cells were examined by immunofluorescence for counting fatty acid binding protein 7 (FABP7)-positive cells.mRNA and protein levels of RhoA and ROCK were detected by quantitative real time polymerase chain reaction (PCR) and Western blot,respectively.Results (1) Data of group Ⅰ were presented as standard,the number of FABP7 positive cells in group Ⅰ,group]Ⅱ,group Ⅲ,group Ⅳ,group Ⅴ was (100.0 ±1.6)％,(63.8 ±5.2)％,(82.8 ±4.3)％,(78.6 ± 2.7) ％,and (87.6 ± 3.2) ％,respectively.Compared with group Ⅰ,FABP7 positive cells in group Ⅱ decreased significantly by approximately 36％ (t =14.98,P ＜0.01).The number of FABP7 positive cells in group Ⅱ,group Ⅳ,group Ⅲ and group Ⅴ increased gradually and there were significant differences among the groups(F =66.53,P ＜0.01).(2) The levels of RhoA mRNA in group Ⅰ,group Ⅱ,group Ⅲ,group Ⅳ,group Ⅴ were 1,3.05 ± 0.36,2.15 ± 0.19,1.89 ± 0.11,and 1.66 ± 0.11 respectively;the levels of ROCK Ⅱ mRNA in group Ⅰ,group Ⅱ,group Ⅲ,group Ⅳ,group Ⅴ were 1,2.78 ± 0.27,2.12 ± 0.21,1.74 ± 0.12,and 1.65 ± 0.05,respectively.Cells of group Ⅱ showed a statistically higher level of RhoA and ROCK Ⅱ mRNA than those of control cells(t =-12.61,-14.67,all P ＜ 0.01).The levels of RhoA and ROCK Ⅱ mRNA in group Ⅱ,group Ⅲ,group Ⅳ,group Ⅴ decreased gradually,and there were significant differences among the groups(F =73.20,76.38,all P ＜ 0.01).(3)The levels of RhoA protein in group Ⅰ,group Ⅱ,group Ⅲ,group ⅢⅣ,group Ⅴ were 0.37 ± 0.03,0.87 ± 0.02,0.73 ± 0.04,0.72 ± 0.04,and 0.55 ± 0.04 respectively;the levels of ROCK Ⅱ protein in group Ⅰ,group Ⅱ,group Ⅲ,group Ⅳ,group Ⅴ were 0.46 ± 0.03,0.96 ± 0.02,0.74 ± 0.01,0.63 ± 0.02,and 0.55 ± 0.03,respectively.The levels of RhoA and ROCK Ⅱ protein were significantly higher in group Ⅱ than those in group Ⅰ (t =-27.60,-35.77,all P ＜ 0.01).The levels of ROCK Ⅱ protein in group Ⅱ,group Ⅲ,group Ⅳ,group Ⅴ reduced gradually,and there were significant differences among the groups(F =390.16,P ＜ 0.01).The levels of RhoA protein in group Ⅱ,group Ⅲ,group Ⅴ reduced gradually,and there were significant differences among the groups (F =130.51,P ＜ 0.01),but there was no significant difference between group Ⅲ and group Ⅳ (t =0.46,P ＞ 0.05).Conclusions Taurine supplementation can promote the proliferation of NSCs in IUGR fetal rats by inhibiting Rho/ROCK signaling pathway,thus to improve IUGR fetal brain development.