Autophagy marker dynamics in the fetal brain and placenta of rats in hyperhomocysteinemia

BACKGROUND: Autophagy is essential for placenta formation and fetal brain development. Maternal hyperhomocysteinemia is a risk factor for pregnancy complications and may affect autophagy processes. However, the dynamics of autophagy markers are not studied enough so far. AIM: The aim of this study was to assess the dynamics of key autophagy markers in the fetal brain and various parts of the placenta of rats throughout pregnancy under normal conditions and in the presence of maternal hyperhomocysteinemia. MATERIALS AND METHODS: Pregnant Wistar rats were induced with hyperhomocysteinemia by chronic administration of L-methionine. Placental and fetal brain tissues were collected on days 14 and 20 of gestation. Levels of autophagy markers (Beclin-1; phosphatidylethanolamine conjugated form microtubule-associated protein 1A/1B light chain 3B (LC3B-II); lysosomal associated membrane protein 2 (LAMP-2)] were determined by Western blotting. Ultrastructural changes were examined using electron microscopy. RESULTS: In the control group, by the end of pregnancy (gestational day 20) compared to gestational day 14, we observed an increase in LAMP-2 level in the maternal part of the placenta and a decrease in LC3B-II level in the fetal part of the placenta. In maternal hyperhomocysteinemia in the maternal part of the placenta, we found an increase in LAMP-2 level on gestational day 14 and in LC3B-II level from gestational day 14 to gestational day 20. In the fetal part of the placenta, under the same conditions, we observed a decrease in LC3B-II level on gestational day 14 and an increase in LAMP-2 level by the end of pregnancy. In the fetal brain, a decrease in Beclin-1 level from gestational day 14 to gestational day 20 was shown in the both study groups, while under the influence of hyperhomocysteinemia, the levels of the autophagy markers remained unchanged. Under L-methionine load, pathological ultrastructural changes were observed in the fetal part of the placenta and fetal brain at the both time points studied. Normally and under the influence of hyperhomocysteinemia, autophagosomes were found in placental cells on gestational days 14 and 20, while in brain cells, they were only present on gestational day 20. CONCLUSIONS: The data obtained suggest that autophagy activity in the placenta and fetal brain in normal conditions and under maternal hyperhomocysteinemia depends on the gestational age. Changes in the dynamics of autophagy may be a reason for impaired placental formation and dysfunction in hyperhomocysteinemia. The absence of significant changes in autophagy markers in the fetal brain under hyperhomocysteinemia conditions may result from protective mechanisms in the placenta or/and the resilience of autophagy processes in nervous tissue.