Effect of chronic stress on KYN, IDO, and TRP in hippocampus of depression model rats and the electro-acupuncture effect

Abstract

Objective To observe the changes of kynurenine(KYN), Indoleamine 2, 3 oxidase (IDO), and tryptophan (TRP) in chronicity stress depression model rats and the effect of electro-acupuncture (EA), and to explore the effect of kynurenine pathway in the onset and treatment of depression. Methods The study was performed after the rats were allowed to acclimate for 1 week. The chronic unpredictable mild stress and solitarily feeding method were used to make the depression models. After 21 consecutive days’ chronic unpredictable mild stress, the hippocampus was collected, and the levels of TRP, IDO, KYN were detected by ELISA. Results The cross and rear scores were significantly lower in the model group than in the control group [(37.40±10.13) vs. (60.00±19.74) and (4.20±2.94) vs. (16.33±2.94); both P<0.05], and were higher in the EA group and the fluoxetine group than in the model group (all P<0.5). The levels of TRP and KYN were higherand the level of IDO was lower in the model group than in the blank group [(0.78±0.81) μg/ml vs. (0.66±0.10) μg/ml, (601.23±18.13) nmol/L vs. (550.18±21.30) nmol/L, and (276.33±36.05) pg/ml vs. (329.89±30.11) pg/ml; all P<0.05]. Compared with those of the model group, the levels of TRP and KYN decreased and the level of IDO increased in the EA group (all P<0.05). Conclusion Electro-acupuncture may relieve depression by adjusting the abnormality of kynurenine pathway. Key words: Depression; Electro-acupuncture; Kynurenine pathway