Establishment Of A Disease Model About Intrahepatic Cholestasis In Pregnant Rabbits And The Study On Alteration Of Cardiac Function In Rabbit Foetus

Background and objective Intrahepatic Cholestasis of pregnancy (ICP) is a disease characterized with skin pruritus, jaundice and hepatic dysfunction in gestation period. Prognosis of perinatal neonates with ICP is poor, which incidence rate of fetal distress in perinatal neonates is 35-65%, mortality rate of neonates with ICP is four times than normal pregnancy. However, little is known about the pathogenesis of fetal complications of ICP. The focus on pathogenesis of fetal distress or stillbirth in perinatal neonates is perfusion of placent-fetus, however there are few studies on role of vital organs dysfunction in fetus in pathogenesis of ICP. the interspace of villus becoming narrow and villus blood vessel spasm lead to decrease of blood flow in placent, which can result in acute anoxia, even death of fetal with ICP when uterine contraction or diffusion dysfunction of placental membrane, however some researches demonstrated that the interspace of villus becoming narrow only decreased capacity of oxygen potentiality and can't lead to stillbirth. Recent researches displayed that taurocholic acid can lead to decrease of contraction intensity and heart rate, bradycardia even asystole. There a great quantity of and lethal congestion point on pericardium. Many clinical studies discovered that non-symptom stillbirth will occur when uterine contraction, simultaneously. All those data show that stillbirth and fetal distress with ICP is resulted by poly-causes. Cardiac dysfunction resulted by myocardial cell damage maybe participate the pathogenesis of fetal complications of ICP. ICP animal model is established in order to observe the alteration of energy metabolism, alteration of cardiac function in rabbit fetal with ex vivo perfusion with normal oxygen and hypoxia. To gain an understanding whether cardiac function and tolerance to hypoxia are suppressed or not in pregnant rabbits with ICP. In order to approach whether or not cardiogenic factor play an important role in pathogenesis of fetal complications of ICP. Methods 1. 32 pregnant rabbits were randomly divided into four groups, benovocylin was subcutaneous injected at dose of 0.2mg·kg^-1·d^-1 in high dose group, 0.1 mg·kg-1·d-1 in moderate dose group, 0.05 mg·kg-1·d-1 in low dose group until delivery and saline was subcutaneous injected in control group until delivery. Biochemical makers were estimated and hepatic pathologic alteration was observed in order to establish suitable animal model. 2. ICP group was randomly divided into group Ⅰand group Ⅱ, control group were divided into group Ⅲand group Ⅳ. Hearts in groupⅠand group Ⅲwas perfused with hypoxia, hearts in group Ⅱand group Ⅳwas perfused with normal oxygen. HR, LVDP, LVEDP, ±dp/dtmax and CF were monitored. The level of CK-MB and CTn-I in outflow from coronary artery were determined. Water content of myocardial tissue was estimated. Ultrastructure of cardiac muscle cell in each group was observed. 3. The level of ATP, SOD and MDA in myocardial tissue of ICP and control groups is estimated. Ultrastructure and number of apoptosis cell were observed. Results 1. The rates of premature labor and fetal death in high, moderate and low dosage groups were significantly higher than control group(P<0.01). Survival rate of rabbit fetus in high dose group is 11.9%, survival rate of rabbit fetus in moderate dose group is 54.4%. Serum level of TBA,AST,ALT,CG in high dose and moderate dose group were significantly higher than control group(P<0.01), serum level of TBA,CG in low dose group were significantly higher than control group(P<0.05 ). Live cell swelling, bile deposition in cytoplasm was observed in high and moderate dose group with light microscope. Mitochondrion swelling, endoplasmic reticulum dilataltion, cholangiectasis, edema, cavitation, bile salt deposition in cytoplasm were observed with electron microscope. Pathologic alteration in low dose group and control group was minimal. 2. Heart rate and cardiac contraction in group Ⅰdecreased at 50% compare with group Ⅱat 15min post-perfusion. Flow of coronary artery significantly reduced and the level of CK-MB, CTn-I in effluent from coronary artery significantly increased compare with control group at 15 min post-perfusion. Flow of coronary artery ingroup Ⅰwas only one tenth of group Ⅱand the level of CK-MB, CTn-I in effluent from coronary artery in group Ⅰadvanced increased at 30 min post-perfusion. Left ventricle contractility striking weaken, bradycardia become extreme. Edema of myocardium tissue was severe at 30 min post-perfusion. Alteration of cardiac function in group Ⅲwas minimal after perfusion. There were significantly difference in preceding maker between group Ⅰand group Ⅱ, group Ⅲ.3.The level of ATP, SOD in embryocardia tissue in ICP group significantly decreased compare with control group, the level of MDA and number of apoptosis cell of embryocardia tissue in ICP group significantly increased compare with control group(P<0.01). Mitochondrion swelling, vacuoles and Myelinoclasis, increasing number of micro-mitochondrion and decreasing of glycogen granule in cytoplasm were observed in ICP group through electron microscope, however alteration of ultrastructure was minimal in control group. Conclusion 1. Subcutaneous injection of benovocylin at dose of 0.2 mg·Kg-1·d-1, 0.1 mg·Kg-1·d-1 can lead to biochemical alteration in circulation and pathologic alteration in liver, which is similar to human ICP. The animal model of 0.1 mg·Kg-1·d-1 dose can meet the demand of this study. 2. Normal cardiac function can be maintained in occasion of normal oxygen, however heart of rabbit foetus with ICP is sensitive and can't tolerance to hypoxia, severe cardiac dysfunction will occur after shour-term hypoxia, furthermore cardiac dysfunction is progressively deteriorated with hypoxia and cardiac arrest will occur at last. 3. Abnormal structure of mitochondrion and disturbance of energy metabolism are found in myocardial cell in rabbit fetus with ICP, which may play an important role in pathogenesis of dead fetus.