OBJECTIVETo determine the changes in the levels of endogenous metabolites in rats with chronic immobilization stress (CIS) taking Xiaoyao Powder (XYP) and its modified prescription version, which lacks the volatile oils extracted from Herba Menthae.

METHODSTwenty-four experimental male SD rats were randomly divided into 4 groups of 6 rats each: control, model, XYP-1 (containing volatile oils from Herba Menthae), and XYP-2 (lacking volatile oils). All rats except control group rats were subjected to CIS 3 h per day for 21 consecutive days. Groups XYP-1 and XYP-2 were given the extracted XYS with or without volatile oils (3.854 g/kg; suspended in distilled water) via gavage 1 h before CIS each day for 21 days. Rats were anesthetized using intraperitoneal injection of pentobarbital sodium (40 mg/kg) on the 22nd day. Observations were made using a Varian INOVA 600 MHz NMR spectrometer at 27 °C. Carr-Purcell-Meiboom-Gill (CPMG) and longitudinal eddy-delay (LED) were applied, resulting in spectra showing only the signals from micro- and macro-metabolites.

RESULTSCompared to controls, rats subjected to CIS showed increased levels of plasma metabolites, such as acetic acid, choline, N-glycoprotein (NAC), saturated fatty acid, and blood sugars. Levels of low-density lipoprotein (LDL), very low-density lipoprotein (VLDL), and unsaturated fatty acids were decreased. The biochemical effects of XYS were characterized by elevated levels of VLDL, LDL, threonine, methionine, and glutamic acid in plasma.

CONCLUSIONSome common and characteristic metabolites on the anti-CIS of XYP and its modified prescription were obtained. The metabolomics technology is a valuable tool and may be used to identify the specific metabolites and potential biomarkers of therapeutic effect of Chinese medicinal prescriptions.