Effects of lipopolysaccharide on the tryptophan-kynurenine metabolic pathway / 中华行为医学与脑科学杂志

ABSTRACT

Objective To investigate the effects of lipopolysaccharide(LPS) on the tryptophan-kynurenine(TRP) metabolic pathway in rat brains and provide new evidence for the relationship between inflammation and depression.Methods Rats in LPS group were given a single dose of 3.5 mg/kg LPS.while the rats in control group were given the same dosage of saline.The dialysis in ventro-hippocampus were collected by microdialysis within 8 hours and then the TRP,KYN and KA were detected by LC-MS/MS.And the expression of indoleamine 2,3-dioxygenase was detected by Western-blot.Results The level of TRP((550.15± 107.96) pmol/L) and KYN ((337.95±62.73) pmol/L) showed a time-dependent increase after administration LPS 4 h compared with the control group(TRP (368.38±59.31) pmol/L,KYN (172.80±43.96) pmol/L),while KA level in the circulation exhibited a trend to decrease,especially at 7 h ((3.47±0.62) pmol/L,P＜0.05).The ratio of KYN/TRP significantly increased at about 5 h (0.69±0.11,P＜ 0.05),and an ratio of KA/KYN (0.02±0.00) was dramatically decreased after administering LPS 4 h compared with the control group (0.05±0.01)(P＜0.05).Most of the analytes showed more dramatic changes around 4 h to 8 h.LPS group(1.48±0.37) increased the protein expression of indoleamine 2,3-dioxygenase compared with the control group(1.00±0.24) (P＜0.01).Conclusions LPS may cause tryptophan metabolic abnormalities and accelerate the way of kynurenine metabolism,leading to decreased the kynurenic acid status.