Branched-chain Amino Acids Supplementation Ameliorates Mental Fatigue In Rats Subjected To Sleep Deprivation

Objective The effects of branched-chain amino acids (BCAA) supplementation on the active behaviors, serum levels of free fatty acids (FFA) and amino acids, metabolism of neurotransmitters, and the expression of tryptophan hydroxylase (TPH) mRNA in brain stem were studied in rats subjected to sleep deprivation to provide theoretic basis of the mechanism and nutritional intervention of mental fatigue. Method To induce mental fatigue, sleep deprivation was adopted in male Sprague-Dawlay rats by employing "flower pot" technique. Fifty-six rats were divided into seven groups randomly: C (control group), 24hSD(being sleep-deprived for 24 hours), 24hSDB(being sleep-deprived for 24 hours and fed fodder enriched with BCAA), 48hSD, 48hSDB, 72hSD and72hSDB. After sleep deprivation, the behaviors of rats were studied by open-field test (OFT); serum level of FFA was measured by colorimetry; BCAA levels in blood were determined by amino acids analytical method; concentrations of 5-hydroxytryptamine (5-HT) , 5-hydroxyindolacetic acid (5-HIAA) in brain stem and hypothalamus and serum level of tryptophan (Trp) were measured using the fluorospectrophotometry by their natural fluorescence; and the expression of TPH mRNA in brain stem was determined by semiquantitative reverse-transcription polymerase chain reaction (RT-PCR). Results 1. Compared with the control group, the OFT scores increased significantly in all sleep-deprived groups (P<0.05), the 48hSD group showing the highest OFT scores. The OFT scores in 72hSD group were lower than that in 72SDB rats (P<0.05). 2. Compared with the control group, the serum FFA level increased significantly in sleep-deprived rats (P<0.05). The difference enlarged with the extension of sleep deprivation time. The serum level of FFA in 72hSDB group was lower than that in 72hSD group (P<0.05). 3. Compared with the control group, the serum level of F-Trp increased significantly in sleep-deprived rats (PO.05) in accordance to sleep deprivation time. The serum concentration of BCAA in sleep-deprived rats was slightly lower than but not significantly different from that in the control group (P>0.05), but the ratio of BCAA/Trp decreased markedly compared with the control group. In the groups supplememted with BCAA the serum levels of BCAA and BCAA/Trp increased significantly (P<0.05) compared with the groups without BCAA supplementation. 4. Compared with the control group, the concentrations of 5-HT, 5-HIAA in the two brain regions increased significantly in sleep-deprived rats (P<().05 in accordance to sleep deprivation time. 5-HIAA/5-HT ratios increased significantly in 24hSD in the hypothalamus and brain stem, but the ratios decreased in 48h and 72hSD groups. In the groups supplemented with BCAA the concentrations of 5-HT and 5-HIAA decreased significantly in 48h and 72hSD groups, but the ratios of 5-HIAA/5-HT did not change. 5. Expressions of TPH mRNA in the brain stem in 24h and 48h sleep-deprived groups were not significantly different from that in the control group (P>0.05), but increased significantly at 72h sleep deprivation (P<0.01). Expressions of TPH mRNA in the groups supplemented with BCAA were not significantly changed compared with the groups without BCAA supplementation. Conclusion The active behavior of rats is excited by sleep deprivation and oral supplementation of BCAA may improve the behavior deficit; Oral supplementation of BCAA may reduce serum level of FFA and enhance the serum level of BCAA/Trp in rats subjected to sleep deprivation; supplementation of BCAA may reduce the concentrations of 5-HT and 5-HIAA in two brain regions in rats subjected to sleep deprivation; Seventy two hour sleep deprivation enhances the expressions of TPH mRNA in rat brain stem; oral supplementation of BCAA doesn't alter the change.