The Effects Of Melatonin On Lipopolysaccharide-induced TNF-α And IL-10 Levels In Rats During Pregnancy

Objective:To investigate the effects of melatonin on LPS-evoked releases of cytokines in maternal serum and fetal brain.Methods:The d19 of pregnant Sprague-Dawley rats were divided randomly into three groups. All pregnant rats except controls(saline)received an intraperitoneal(i.p.) injection of LPS(500μg/kg). In melatonin groups,pregnant rats were treated with MT 10mg/kg (i.p.), according the time of MT injection, the pregnant rats were divided into four groups respectively: LPS at the same time, at 30 min before LPS, at 2 hour before LPS, at 6 hour before LPS. All rats were sacrificed at 1.5h after LPS. Blood serum were collected for measurements of TNF-αand IL-10 by ELISA. Fetal brains were dissected for measurements of TNF-αand IL-10 by ELISA. The SPSS 16.0 statistical software package was used for all calculations, A p value﹤0.05 was considered to indicate statistical significance.Results:1. The effects of melatonin on LPS-evoked releases of cytokines in maternal serum:1.1 The effects of melatonin on LPS-evoked releases of TNF-αin maternal serum: Comparing with the control group, all LPS injection of pregnant rats, serum TNF-αprotein content were significantly increased (P <0.001); with the LPS group, the serum TNF-αconcentration of MT groups decreased (P <0.001); and with the treatment group of MT and LPS at the same time, the serum levels of TNF-αdecreased in MT pretreatment groups.1.2 The effects of melatonin on LPS-evoked releases of IL-10 in maternal serum:IL- 10 levels in all LPS injection of pregnant rats were more than that in the control group; Comparing with LPS group, the serum IL-10 protein content were significantly increased (P<0.005) in MT-treat-ment groups; and with MT and LPS treatment simultaneously group, the serum levels of IL-10 rised in MT pretreatment 30 minute and 2 hour groups however dropped in the group that melatonin injection at 6 hour before LPS. 2. The effects of MT on LPS-stimulated cytokines production in fetal brain:2.1 The effects of melatonin on LPS-evoked releases of TNF-αin fetal brain:Maternal LPS exposure increased the levels of TNF-αin fetal brain (P<0.05),Melatonin effectually inhibited LPS-induced TNF-αin fetal brain;And LPS with the MT group at the same time, MT pretreatment group decreased TNF-αbut no significant difference.2.2 The effects of melatonin on LPS-evoked releases of IL-10 in fetal brain:After 1.5h treatment with LPS, the IL-10 production were rised(P<0.05); the content of IL-10 in fetal brain were higher in the MT treatment groups than the LPS group (P<0.05); To compare with the MT and LPS at the same time treatment group, IL-10 elevated in MT30'+ LPS group and MT2h + LPS group, and which is maximum in MT2h + LPS group.3. Correlation analysis showed that:pregnant mice after exposure to LPS of serum TNF-αand IL-10 secretion was positively correlated (r=0.531, P= 0.003), so did in TNF-αlevels of fetal brain and serum secretion (r=0.667, P<0.001), Correlation analysis showed no linear association between TNF-αand IL-10 levels in fetal brain(r=0.107, P =0.574), concentration of IL-10 in fetal brain added as more the IL-10 level in serum of pregnant rats increased(r =0.726, P<0.001).Conclusion:①.LPS infection in late pregnancy increases maternal blood levels of inflammatory cytokines, and LPS exposure in late pregnancy also elevates TNF-α, IL-10 content in fetal brain;②. The protective effect of MT on LPS-induced intrauterine infection may be related to melatonin differentially regulates LPS-induced proinflammatory and antiinflammatory cytokines release;③.Compared with LPS and melatonin treatment simultaneously, the protective effects of melatonin pretreatment was more obvious.