| Objective：Salacia oblonga root (SOR) is a traditionally herbalmedicine for obesity and diabetes, which are closely associated with fattyliver. SOR has been demonstrated to improve fatty liver. This study aimedto investigate the molecular mechanisms of SOR in the treatment ofdietary-induced fatty liver.Methods：24rats were randomly divided into4groups (n=6pergroup), administered for10weeks.(1) control group: free access to water;(2) fructose group: free access to10%fructose solution (w/v, preparationevery day);(3)SOR low concentration group: fructose solution+SOR5mg/kg (4)SOR high concentration group: fructose solution+SOR20mg/kg. The weight was recorded every three days and the drug dosagewas adjusted According to the weight change in rats. The initial fructose solution concentrations of SOR groups were both10%. The consumedchow and fructose solution were measured daily and the intake of fructosewas calculated. The fructose concentration was adjusted based on theresults in the fructose group during the previous3days. On10weeks， ratswere deprived of chow, but still had free access to water over night. Bloodsamples were collected by retroorbital venous puncture under etheranesthesia for determination of plasma concentrations of TG, TC, NEFA,glucose and insulin. Immediately, animals were weighed and killed byprompt dislocation of the neck vertebra. Liver was collected and weighed.A portion of liver was cut and stained with H.E and Oil Red O. Meanwhilethe liver concentrations of TG and TC were determined; Total RNA wasisolated from livers of individual rats using TRIzol, cDNA was synthesizedusing M-MLV RTase cDNA Synthesis Kit according to the manufacturer’sinstructions. Real-Time PCR was performed to test liver lipid synthesisrelated genes expression of SREBP-1c, ChREBP, FAS, ACC-1, SCD-1,LPK, and lipid oxidation related genes expression of PPAR-α, PPAR-γ,CPT-1a, ACO, CD36. Nuclear protein was prepared individually fromlivers using the NE-PER nuclear and cytoplasmic extraction reagent kitaccording to the manufacturer’s instructions. Nuclear proteins ofSREBP-1c and ChREBP, which were the two main transcription factorsregulating lipid synthesis, were demonstrated by Western blot analysis;Data were analyzed by the StatView software, and all results were expressed as x±SEM and the two group of data were compared by T-test.Results：1.Biochemical indicators: compared to control group, fructose groupsignificantly increased plasma levels of TC, TG, glucose and insulin, whileNEFA decreased significant (P<0.05); relative to fructose group, SORgroups did not show significant effect on plasma concentrations of TC, TG,glucose, insulin and NEFA(P＞0.05).2. Liver related parameters: Each group had no difference in liver weightand TC levels(P＞0.05); compared to control group, fructose groupsignificantly increased the ratio of liver weight to body weight and TGcontent; SOR(20mg/kg) relative to fructose group, TG content in liverdecreased large(P <0.05).3. Histological examination:(1) H.E staining, the vacuolization in liver cellincreased from fructose group compared with control group, SOR(20mg/kg)could reduce the vacuolization;(2) the ORO staining, compared to controlgroup, fructose group significantly increased Oil Red O staining area,SOR(20mg/kg) obviously improved Oil Red O staining area(P <0.05).4. Real-Time PCR results: compared to control group, fructose groupclearly increased mRNA levels of SREBP-1c, FAS, ACC-1, SCD-1,ChREBP and LPK, meanwhile it decreased mRNA levels of ACO andCPT-1α(P <0.05), then it did not show large effect on the levels of PPAR-γ,PPAR-α, and CD36(P＞0.05); SOR(20mg/kg) distinctly diminished SREBP-1c, FAS, ACC-1, SCD-1and ChREBP mRNA levels(P <0.05), ithad no change on LPK, PPAR-γ, PPAR-α, ACO, CPT-1α and CD36mRNAlevels(P＞0.05).5. Western blot analysis: compared to control group, The increase innuclear SREBP-1c and ChREBP protein content was demonstrated infructose group(P<0.05); SOR(20mg/kg) suppressed fructose-stimulatedoverexpression of nuclear SREBP-1c protein expression(P<0.05), but it didnot significantly alter nuclear ChREBP protein content(P＞0.05).Conclusions1. SOR (20mg/kg) can improve high fructose-induced fatty liver in rats.2.The hepatic SREBP-1c is an important molecular target of SOR in theimprovement of high fructose-induced fatty liver in rats. |
