Objective: To investigate the effect of magnesium sulfate on the fetal rats of fetal growth retardation (FGR) and its relation with expression of caspase-3 on the placenta of maternal rat.
Methods: Model of FGR was constructed according to the method of passive smoking. The pregnant rats were divided into control group (n = 10), therapy group (n = 18) and FGR group (n = 10). The therapy group rats were given different doses of magnesium sulfate by subcutaneous injection: low dose group (300 mg/kg, n = 10), high dose group (600 mg/kg, n = 8). Serum concentration of magnesium sulfate was monitored. The expression of caspase-3 was measured by immunohistochemistry method and RT-PCR.
Results: Both of the concentration of magnesium sulfate in high and low dose groups (0.72 +/- 0.13), (0.61 +/- 0.03) mmol/L were higher than the FGR group (0.55 +/- 0.03) mmol/L (P < 0.01); the weight of placenta and fetal rat in high dose group [(0.80 +/- 0.16) and (3.58 +/- 0.10) g] were more than those of FGR group [(0.63 +/- 0.05) and (2.95 +/- 0.46) g] (P < 0.05, P < 0.01); the expression of mRNA and protein of caspase-3 in high dose group [(0.361 +/- 0.030), (183.0 +/- 3.3)] was lower than the FGR group [(0.626 +/- 0.036), (199.5 +/- 4.7)] (P < 0.05); the expression of mRNA in low dose group (0.525 +/- 0.029) was higher than the high dose group (P < 0.05); serum concentration of magnesium sulfate of maternal rat was correlated with the weight of fetal rat (r = 0.899, P = 0.038) and the expression of mRNA and protein of caspase-3 in placenta (r = -0.747, P = 0.033; r = -0.915, P = 0.001).
Conclusion: It is suggested that magnesium sulfate increases the weight of fetal rat probably by depressing the expression of caspase-3 of placenta, which improves the placental function.