Adult male Sprague-Dawley rats weighing 230 ± 10 g were obtained from the Animal Breeding Centre of Beijing Vital River Laboratories Company (Beijing, China). The project identification code was 20162005. All animals were housed at 22 ± 2°C with a relative humidity of 50 ± 10% and a 12 h light/12 h dark cycle. The animals had free access to water and fodder (Beijing Keaoxieli Co. Ltd.). All experimental animal procedures were approved by the China Academy of Chinese Medical Sciences' Administrative Panel on Laboratory Animal Care and performed in accordance with institutional guidelines and ethics of the committee as part of the China Academy of Chinese Medical Sciences (February 1st, 2016).
Ten AA standards including alanine, valine, taurine, leucine, isoleucine, glutamine, glutamate (glutamic acid), phenylalanine, (S)-tyrosine, and tryptophan (purity > 99%, all) were purchased from Sigma-Aldrich (St. Louis, MO, USA). Acetonitrile and methanol were provided from Fisher Scientific (Shanghai, China). Formic acid, ammonium formate, and phenylalanine-d5 (internal standard (IS)) were purchased from Toronto Research Chemicals (YTO, Canada). All chemicals used throughout this study were of HPLC grade unless stated otherwise. BNC (batch number: 140156) was provided from Buchang Pharma Co. Ltd.
Ten AA standards including alanine, valine, taurine, leucine, isoleucine, glutamine, glutamate (glutamic acid), phenylalanine, (S)-tyrosine, and tryptophan (purity > 99%, all) were purchased from Sigma-Aldrich (St. Louis, MO, USA). Acetonitrile and methanol were provided from Fisher Scientific (Shanghai, China). Formic acid, ammonium formate, and phenylalanine-d5 (internal standard (IS)) were purchased from Toronto Research Chemicals (YTO, Canada). All chemicals used throughout this study were of HPLC grade unless stated otherwise. BNC (batch number: 140156) was provided from Buchang Pharma Co. Ltd.