Association between the transcriptional levels of Htr-1a and tryptophan hydroxylase-1 in the hippocampus and the antifatigue effects of leucine on rats with postoperative fatigue

Leucine (Leu), a branched-chain amino acid (BCAA), is widely used in clinical practice following severe burns, gastrointestinal surgery, trauma and sepsis. In the present study, the antifatigue effects of BCAAs on a postoperative fatigue (POF) rat model, induced by 70% intestinal resection, were investigated. Leu (16.5 g/l) was administered intraperitoneally at a dose of 18 ml/kg/day. The fatigue level and antifatigue effects of Leu were evaluated by open-field testing on day 1, 3, 5 and 7 after surgery. In addition, mRNA specimens were extracted and measured using a quantitative polymerase chain reaction method. The open-field test results indicated that Leu exhibited a significant antifatigue effect. The total distance travelled and the number of times the rats passed from the outermost grids of an open-top case were greatly improved in the Leu treatment group when compared with the POF model group. With the exception of the normal group, the mRNA expression levels of Htr-1a exhibited a similar trend in all other groups, reaching a climax on day 3 and 5, while being restored to a normal level on day 7. With regard to the Leu intervention group, the mRNA expression level of Htr-1a decreased significantly on day 3 and 5 following surgery. The mRNA expression levels of tryptophan hydroxylase-1 were unchanged in this short time period; however, the levels were increased gradually in the Leu treatment group. Therefore, Leu exhibited an apparent antifatigue effect on various 5-hydroxytryptamine-associated genes.