CYCLOOXYGENASE-1 AND CYCLOOXYGENASE-2 IN HUMAN PLACENTA AND PLACENTALBED AFTER NORMAL AND PREECLAMPTIC PREGNANCIES

In pre-eclampsia, the ratio of prostacyclin:thromboxane production rat e is decreased favouring the vasoconstrictive thromboxane. One of the rate-limiting steps in prostaglandin synthesis is cyclooxygenase (COX) activity. Therefore, we investigated the expression of COX-1 and COX- 2 in human placenta and placental bed. Tissue specimens from the 29th to 40th week of pregnancy were obtained from Caesarean sections after uncomplicated and preeclamptic pregnancies before the onset of labour. COX-1 and COX-2 were localized immunohistochemically with the identif ication of positive cells by double immunofluorescence staining. The p rotein and mRNA levels were analysed by immunoblotting and quantitativ e reverse transcriptase-polymerase chain reaction. Expression of both COX-1 and COX-2 could be observed in placenta and placental bed. COX-1 -like immunoreactivity was observed in most cell types with strongest staining in macrophages. Only macrophages, endothelium, vascular leiom yocytes and fibroblasts stained positively for COX-2. In placenta, COX -1 and -2 expression was unchanged after pre-eclampsia. In placental b ed, protein and mRNA levels of COX-1 were increased in the pre-eclampt ic group (P < 0.05), whereas COX-2 expression did not differ significa ntly from normal pregnancies. An increased expression of COX-1 could b e involved in the pathophysiology of pre-eclamptic changes within the placental bed. A therapy with drugs inhibiting COX-1 might be benefici al in this condition.