The placenta is a major source of leptin in the fetomaternal circulation, although its physiological role remains to be clarified. Leptin in the fetomaternal circulation is proposed to be a marker of acute stress in the fetus, and the fetus suffering from pre-eclampsia would be under chronic stress. In 16 pre-eclamptic placentas, the expressions of leptin, hypoxia-inducible factor 1alpha (HIF1alpha) and leptin receptor mRNAs were analyzed by semi-quantitative reverse-transcriptase-polymerase chain reaction and compared with clinical data. The co-expressions of leptin and the isoforms of the leptin receptor were observed in all the pre-eclamptic placentas. Leptin mRNA was significantly augmented in the pre-eclamptic placentas, although the level in fetal plasma was not high. The level of the expression of leptin mRNA was correlated with the placental HIF1alpha mRNA level and fetal body weight, but not with the levels of the leptin receptor isoforms in the pre-eclamptic placentas. This observation may suggest that autocrine/paracrine regulation of leptin exists in the human placenta and is upregulated in the pre-eclamptic placenta.
This study was designed to examine the biological implications of progesterone receptor form A (PR-A) and B (PR-B) mRNA expressions in human ovarian endometriosis (ectopic endometrium). A high ratio of PR-B to PR-AB (PR-A+PR-B) mRNA expression was found in 8 of 14 cases of endometriosis, compared with the ratio in eutopic endometrium. The mean ratio in ectopic endometria was significantly (p < 0.01) higher than in eutopic endometria. The ratio in eutopic and ectopic endometria showed no significant change during the menstrual cycle. The mean ratio in ectopic endometria in the proliferative and secretory phases of the endometrium was significantly (p < 0.01) higher than in eutopic endometria. In conclusion, PR-B mRNA was relatively highly expressed in some endometriomas, which might lead to aberrations in the control of progestational effects involving responsiveness to sex steroidal growth regulation.
To understand the biological significance of progesterone receptor forms A (PR-A) and B (PR-B) in human corpus luteum, the expression of mRNA and serum steroid hormone concentrations were determined simultaneously in the luteal stages. The expression of PR-A mRNA predominated over PR-B mRNA in all samples analysed. Total PR (PR-AB) and PR-B mRNA concentrations at the late secretory phase were significantly (P < 0.01) lower than those at the early and mid secretory phases of the menstrual cycle. The ratio of PR-B to PR-AB mRNA concentration showed no significant change during the secretory phase. In the early and mid secretory phases, there was a negative correlation between PR-B mRNA concentration and serum progesterone concentration, and between the ratio of PR-B to PR-AB mRNA concentrations and serum progesterone concentration (P < 0.01). These findings suggest that human corpus luteum might intracellularly synthesize PR-A and PR-B, and thus be involved in the steroid functional regulation of the corpus luteum, especially at the early and mid secretory phases, and that progesterone might regulate the synthesis of PR-A and PR-B.
To investigate the role of oestrogen receptor beta (ERbeta) in the function of human ovarian corpus luteum, the levels of luteal ERalpha and ERbeta mRNA were determined using competitive reverse transcription-polymerase chain reaction-Southern blot analysis. The expression of ERalpha and ERbeta mRNA was detected in all luteal samples analysed. Luteal ERalpha and ERbeta mRNA levels were significantly lower (P<0.01 and P<0.05 respectively) at the late secretory phase than those at the early and mid-secretory phases of the endometrium. The ratio of ERalpha to ERbeta mRNA levels showed no change during the secretory phase of the endometrium. This study demonstrates that ERbeta is co-expressed with ERalpha in human corpus luteum and is likely to play a biological role in the regulation of steroidal action of the corpus luteum with ERalpha.
We demonstrated the expression of corticosteroid-binding globulin (CBG) in human placenta using reverse transcription-polymerase chain reaction-Southern blot analysis and immunohistochemical and immunoblotting studies. In the RT-PCR-Southern blot analysis, only one predicted PCR product was detected without nonspecific products in all samples of human placenta and 3A (tPA-30-1) human placental cells. In Western blot analysis, polyclonal anti-CBG antibodies recognized a protein of approximately 55 kD in the protein extracts prepared from 3A (tPA-30-1) cells. Additionally, CBG mRNA expression was demonstrated by in situ hybridization in the syncytiotrophoblasts. Immunohistochemical studies performed on the placenta demonstrated the presence of specific immunoreactivity in the syncytiotrophoblast layer surrounding the chorionic villi. These findings suggest that CBG is synthesized in human placenta during pregnancy in addition to its synthesis in the liver.
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