NOVEL APPEARANCE OF PLACENTAL NUCLEAR MONOAMINE-OXIDASE - BIOCHEMICALAND HISTOCHEMICAL EVIDENCE FOR HYPERSEROTONOMIC STATE IN PREECLAMPSIA-ECLAMPSIA

OBJECTIVE: The aim of this study was to explore the relevance of place ntal monoamine oxidase at the subcellular level in the etiology of the hyperserotonomic state in preeclampsia-eclampsia. STUDY DESIGN: The s tudy was conducted on placentas from 20 normal pregnant women and 25 w omen with varied severity of preeclampsia-eclampsia. Placental seroton in and subcellular monoamine oxidase activity were determined. Histoch emical localization of monoamine oxidase was done in placental section s and cell isolates. RESULTS: Placental serotonin increases with sever ity (r(systolic)0.84, r(diastolic)0.83) and monoamine oxidase decrease s (r(systolic)0.86, r(diastolic)0.79). Placental monoamine oxidase sho wed marked changes in preeclampsia-eclampsia. Histochemical localizati on of monoamine oxidase showed diffused low activity evenly throughout the cytoplasm and nucleus of the syncytiotrophoblastic cells in preec lampsia-eclampsia; in contrast, normal placenta showed high activity i n the cytoplasm without any activity in the nucleus of syncytiotrophob lastic cells. Detection of monoamine oxidase activity in nuclei of the placenta in preeclampsia-eclampsia is a novel finding. Monoamine oxid ase activity at the subcellular level further strengthens this observa tion. A severity-dependent decrease was present in the nuclei of place ntas with preeclampsia-eclampsia. The use of specific substrates and i nhibitors revealed the presence of monoamine oxidase in mitochondria a nd nucleus. CONCLUSION: The study delineates an impaired catabolism of placental serotonin in preeclampsia-eclampsia. The novel appearance o f monoamine oxidase in nuclei in proximity to its normal site and low activity resulting in a hyperserotonomic state may lead to preeclampsi a-eclampsia.