OBJECTIVETo explore the intervention of Huayu Qutan Recipe (HQR) on liver SREBP-2 signal pathway of hyperlipidemia rats of Pi deficiency syndrome (PDS).

METHODSTotally 100 SPF grade SD rats were randomly divided into the blank control group, the hyperlipidemia group, the hyperlipidemia treatment group, the PDS hyperlipidemia group, and the PDS hyperlipidemia treatment group, 20 in each group. Common granular forage was fed to rats in the blank control group. High fat forage was fed to rats in the hyperlipidemia group and the hyperlipidemia treatment group. Rats in the PDS hyperlipidemia group and the PDS hyperlipidemia treatment group were treated with excessive labor and improper diet for modeling. They were administered refined lard by gastrogavage (3 mL each time, twice per day) and fed with high fat forage on the odd days, and fed with wild cabbage freely on even days. The modeling lasted for 30 days. Rats in the hyperlipidemia treatment group and PDS hyperlipidemia treatment group were administered with Huayu Qutan Recipe (20 mL/kg) by gastrogavage, once a day, for 30 successive days. Levels of serum cholesterol (TC), triglyceride (TG), low density lipoprotein cholesterol (LDL-C), high density lipoprotein cholesterol (HDL-C), and serum amylase (AMY) were detected by automatic biochemical analyzer. D-xylose excretion rate was determined using phloroglucinol method. Morphological changes of liver and the lipid deposition in liver were observed using HE stain and oil red O stain respectively, mRNA and protein expression levels of 3-hydroxy-3-methylglutaryl coenzyme A reductase (HMGCR), cholesterol 7α-hydroxylase 1 (CYP7A1), LDL-R, and sterol regulatory element binding protein-2 (SREBP-2) were detected using real time RT-PCR and Western blotting.

RESULTSCompared with the blank control group, serum levels of TC (1.84 ± 0.19 mmol/L, 2.23 ± 0.43 mmol/L) and LDL-C (0.99 ± 0.24 mmol/L, 1.13 ± 0.56 mmol/L) were higher in the hyperlipidemia group and the PDS hyperlipidemia group, serum levels of HDL-C (0.41 ± 0.66 mmol/L, 0.41 ± 0.11 mmol/L) and AMY activities (351 ± 45 mmol/L, 153 ± 30 mmol/L) were lower, and urinary D-xylose excretion rates were lower (26.9 ± 2.1 ng/mL, 15.0 ± 1.7 ng/mL) (all P < 0.05). Lipid deposition occurred in liver cells. Much fat vacuoles occurred in the cytoplasm. Expression levels of HMGCR, CYP7A1, LDL-R, and SREBP-2 mRNA and proteins in liver significantly decreased (P < 0.01). Compared with the hyperlipidemia group, serum levels of TC and LDL-C significantly increased (P < 0. 05), AMY activities and urinary D-xylose excre- tion rates significantly decreased in the PDS hyperlipidemia group (P < 0.01). A large amount of lipid deposition occurred in liver. The atrophy of liver cells was obviously seen. Expression levels of CYP7A1, LDL-R, and SREBP-2 mRNA and proteins in liver were significantly lower (P < 0.01, P < 0.05). Serum levels of TC and LDL-C significantly decreased (P < 0.05), AMY activities and urinary D-xylose excretion rates significantly increased in the hyperlipidemia treatment group (P < 0.01). Expression levels of CYP7A1, LDL-R, and SREBP-2 mRNA and proteins in liver were significantly increased (P < 0.01, P < 0.05). Compared with the PDS hyperlipidemia group, serum level of TC significantly decreased (P < 0.05), HDL-C levels, AMY activities and urinary D-xylose excretion rates significantly increased in the PDS hyperlipidemia treatment group (P < 0.01),expression levels of CYP7A1, LDL-R, and SREBP-2 mRNA and proteins in liver were significantly increased (P < 0.01). Similar changes occurred in the two treatment groups.

CONCLUSIONSPi deficiency exacerbates abnormal serum TC level and the lipid deposition in liver. These might be related to regulating expression levels of LDL-R, HMGCR, and CYP7A1 genes in the SREBP-2 signal pathway. HQR could regulate this pathway to intervene abnormal metabolism of TC.