ABSTRACT
OBJECTIVE: To investigate the mechanisms involved in the mRNA expressions of hCG, LH/CG receptor and in hormone secretion in the trophoblast of normal and abnormal early pregnancy. METHODS: hCG, free Beta-hCG, and progesterone concentrations were measured in serum and the mRNA expressions of alpha,Beta-hCG and LH/CG receptor were measured in the placental trophoblast of 22 spontaneous abortion patients (spontaneous abortion group), 20 normal pregnancy women (normal pregnancy group) and 6 hydatidiform mole patients (hydatidiform mole group). RESULTS: 1. Mean values of serum hCG and free Beta-hCG concentrations were the lowest in spontaneous abortion group (46343.63+/-40404.18 mIU/ml, p<0.001; 31.34+/-61.57 mIU/ml, p<0.01 respectively) among the three groups. Mean progesterone concentration was the lowest in spontaneous abortion group (11.84+/-7.60 ng/ml, p<0.01), too.2. The expression levels of alpha,Beta-hCG were the highest in spontaneous abortion group (4.64+/-5.47, p=0.015; 4.57+/-4.42 p=0.002 respectively). The expression levels of LH/CG receptor were not different statistically among the three groups and they were high at the 5th week of gestation, reaching nadir at the 10th week of gestation when the concentrations of serum hCG showed peak values in normal pregnancy group.3. The correlations between serum hCG and progesterone concentrations were positive in both spontaneous abortion (r=0.827, p<0.001) and normal pregnancy (r=0.438, p=0.054) group. Though they were not significant statistically, the correlations between progesterone concentrations and the levels of alpha,Beta-hCG expressions were negative in both spontaneous abortion (r=-0.237, p=0.289; r=-0.211, p=0.347) and normal pregnancy (r=-0.270, p=0.250; r=-0.235, p=0.318) group. In hydatidiform mole group, the correlation between progesterone concentrations and the levels of Beta-hCG expression was positive (r=0.968, p=0.002). CONCLUSION: Our results suggest that the mechanisms involved in the secretion of hCG, progesterone and the expression of alpha,Beta-hCG, LH/CG receptor be normal in spontaneous abortion as in normal pregnancy and in the both groups, hCG stimulate the secretion of progesterone by autocrine function and control the secretion of itself, through the suppression of the expressions of alpha,Beta-hCG and LH/CG receptors. So the cause of spontaneous abortion in early pregnancy may be not placental dysfunction but the defect of embryo itself with poor placental growth.