Shi Qing-yun, Lin Yu-geng, Zhou Xin, Lin Ying-qi, Yan Shi
Department of Obstetrics and Gynecology, Beijing Shijitan Hospital, Beijing, China.
Zhonghua Fu Chan Ke Za Zhi. 2010 Jun;45(6):440-4.
To investigate the relationship between interaction of peroxisome proliferators-activated receptor alpha (PPARα), cytochrome P450 oxysterol 7α-hydroxylase (CYP7B1) and estrogen receptor (ER) and intrahepatic cholestasis in pregnant rats.
Eighty clean SD pregnant rats were selected and divided into four groups randomly with 20 in each. Since the 13th day of pregnancy, rats in the control group was injected subcutaneously with refined vegetable oil 2.0 ml×kg(-1)×d(-1), those in the low-dose, moderate-dose and high-dose groups received 17-α-ethynylestradiol (EE) 1.0 mg×kg(-1)×d(-1), 1.25 mg×kg(-1)×d(-1) and 1.5 mg×kg(-1)×d(-1), respectively. All rats were sacrificed at the 21(st) day of pregnancy and maternal hepatic tissues were collected. The serum levels of alanine aminotransferase (ALT), aspartate transaminase (AST), total bile acid (TBA) and bilirubin (BIL) were determined by enzyme linked immunosorbent assay (ELISA). The mRNA expressions of PPARα, CYP7B1, ERα and ERβ in maternal rat livers were examined by real-time PCR.
(1) Biochemical indicators: the serum levels of ALT, AST, TBA and BIL were significantly lower in the control group than in the rest 3 groups, respectively [control group: (41.1 ± 2.8) U/L, (44.4 ± 3.6) U/L, (26.4 ± 5.6) µmol/L and (2.8 ± 0.2) U/L; low-dose group: (48.2 ± 3.4) U/L, (47.9 ± 3.7) U/L, (36.4 ± 4.2) µmol/L and (4.2 ± 0.2) U/L; moderate-dose group: (70.4 ± 5.3) U/L, (68.4 ± 5.6) U/L, (64.3 ± 3.8) µmol/L and (6.2 ± 1.2) U/L; high-dose group: (72.4 ± 7.6) U/L, (70.2 ± 3.8) U/L, (72.4 ± 7.8) µmol/L and (8.2 ± 2.2) U/L, P < 0.05], and those in the moderate or high-dose groups were higher than in the low-dose group (P < 0.05). (2) mRNA expression of ERα and ERβ: the mRNA expression of ERα in pregnant rat livers increased in a dose-dependent manner, which were all significantly higher than that in the control group, respectively (low-dose group: 0.76 ± 0.02); moderate-dose group: (0.99 ± 0.04; high-dose group: 1.21 ± 0.01; control group: 0.65 ± 0.01, P < 0.05), but no difference was found among the 4 groups in the mRNA expression of ERβ (P > 0.05). (3) mRNA expression of CYP7B1 and PPARα: the mRNA expression of CYP7B1 in pregnant rat livers increased from the low-dose group to the high-dose group, and were all higher than that of the control group (low-dose group: 0.93 ± 0.01; moderate-dose group: 0.99 ± 0.06; high-dose group: 1.22 ± 0.04; control group: 0.75 ± 0.02, P < 0.05). However, the mRNA expression of PPARα decreased from the low-dose group to the high-dose group, and were all lower than that of the control group (low-dose group: 0.83 ± 0.05; moderate-dose group: 0.71 ± 0.02; high-dose group: 0.64 ± 0.03; control group: 1.35 ± 0.05; P < 0.05).
The down regulated mRNA expression of PPARα, caused by higher dose of estrogen, may increase the expression of CYP7B1 due to the ineffectiveness of the inhibition of PPARα on CYP7B1, which may further stimulate the ERα activity and then induce intrahepatic cholestasis. Abnormal expression of PPARα, CYP7B1 and ER may play a role in the pathogenesis of estrogen-induced intrahepatic cholestasis.
探讨过氧化物酶体增殖物激活受体α（PPARα）、细胞色素P450氧化甾醇7α-羟化酶（CYP7B1）与雌激素受体（ER）相互作用与孕鼠肝内胆汁淤积的关系。
选取80只清洁级SD孕鼠，随机分为4组，每组20只。自妊娠第13天起，对照组孕鼠皮下注射精制植物油2.0 ml×kg⁻¹×d⁻¹，低剂量组、中剂量组和高剂量组孕鼠分别皮下注射17-α-乙炔雌二醇（EE）1.0 mg×kg⁻¹×d⁻¹、1.25 mg×kg⁻¹×d⁻¹和1.5 mg×kg⁻¹×d⁻¹。所有孕鼠于妊娠第21天处死，采集母鼠肝脏组织。采用酶联免疫吸附测定法（ELISA）检测血清丙氨酸氨基转移酶（ALT）、天冬氨酸氨基转移酶（AST）、总胆汁酸（TBA）和胆红素（BIL）水平。采用实时荧光定量PCR检测母鼠肝脏中PPARα、CYP7B1、ERα和ERβ的mRNA表达。
（1）生化指标：对照组血清ALT、AST、TBA和BIL水平分别显著低于其余3组[对照组：（41.1±2.8）U/L、（44.4±3.6）U/L、（26.4±5.6）μmol/L和（2.8±0.2）U/L；低剂量组：（48.2±3.4）U/L、（47.9±3.7）U/L、（36.4±4.2）μmol/L和（4.2±0.2）U/L；中剂量组：（70.4±5.3）U/L、（68.4±5.6）U/L、（64.3±3.8）μmol/L和（6.2±1.2）U/L；高剂量组：（72.4±7.6）U/L、（70.2±3.8）U/L、（72.4±7.8）μmol/L和（8.2±2.2）U/L，P<0.05]，且中、高剂量组均高于低剂量组（P<0.05）。（2）ERα和ERβ的mRNA表达：孕鼠肝脏中ERα的mRNA表达呈剂量依赖性增加，均显著高于对照组（低剂量组：0.76±0.02；中剂量组：0.99±0.04；高剂量组：1.21±0.01；对照组：0.65±0.01，P<0.05），但4组间ERβ的mRNA表达差异无统计学意义（P>0.05）。（3）CYP7B1和PPARα的mRNA表达：孕鼠肝脏中CYP7B1的mRNA表达从低剂量组到高剂量组逐渐增加，均高于对照组（低剂量组：0.93±0.01；中剂量组：0.99±0.06；高剂量组：1.22±0.04；对照组：0.75±0.02，P<0.05）。然而，PPARα的mRNA表达从低剂量组到高剂量组逐渐降低，均低于对照组（低剂量组：0.83±0.05；中剂量组：0.71±0.02；高剂量组：0.64±0.03；对照组：1.35±0.05，P<0.05）。
高剂量雌激素导致PPARα的mRNA表达下调，可能因PPARα对CYP7B1的抑制作用失效而增加CYP7B1的表达，进而可能进一步刺激ERα活性，从而诱导肝内胆汁淤积。PPARα、CYP7B1和ER的异常表达可能在雌激素诱导的肝内胆汁淤积发病机制中起作用。
