Objective    To explore the effect of ceftriaxone sodium administered intraamniotically and by maternal intravenous injection on the expressions of placental interleukin-6 (IL-6) and matrix metalloproteinase-9 (MMP-9) in treatment of intrauterine infection with E.coli in late pregnant SD rats.     Methods    Thirty-six SD rats on gestation day 15 were randomly divided into four groups (9 in each). On gestation day 15

0.

2 ml E. coli suspension at a dose of 10

10

/L was inoculated into one horn of uterus; On gestation day 16

each gestational sac in inoculated side of rats in intrauterine administration (IUA) group and control (IUC) group was given ceftriaxone sodium or appropriate volume of isotonic Na chloride (NS) intraamniotically

and each rat in maternal intravenous injection (IVA) group and control (IVC) group was given ceftriaxone sodium or appropriate volume of isotonic NS intravenously. From the gestation day 17 on

3 rats of each group were sacrificed randomly each day. One of the top 3 sacs in inoculated side of each rat was randomly selected

and the expressions of IL-6 and MMP-9 were analyzed semi-quantitively by immunohistochemical method.     Results    After administration

the levels of IL-6 and MMP-9 in each treatment group were lower than those in the corresponding control groups (P0.05)

and those in IUA group were lower than those in IVA group (P0.05)

but those in IUC group were higher than those in IVC group (P0.05). The levels of IL-6 decreased to the lowest on the 2nd day after administration in both treatment groups (P0.05)

but increased day by day in both control groups

while MMP-9 expressions increased gradually in each group (P0.05).     Conclusion    Compared with maternal intravenous injection

ceftriaxone sodium administered intraamniotically with a single dose is more effective treatment for intrauterine infection of E. coli in late pregnant SD rats

through inhibiting the expressions of IL-6 and MMP-9 in placenta and reducing inflammation and risk of premature rupture of membranes.