Mitochondrial Bioenergetics in Placenta of Crossbred Cattle- Deciphering the Association of Mitochondrial Alterations with Retained Placenta

Abstract

Retention of placenta (RP) in crossbred cattle poses health, reproductive, and economic challenges linked to oxidative stress, hormonal imbalances, and complex causative factors. Emphasizing the key role of mitochondria in oxidative phosphorylation (OXPHOS) and hormone synthesis, our study is the first to explore differences in OXPHOS activity, mitochondrial content, and mtDNA-encoded gene expression between normal and RP. In addition, gross morphological examination of placental tissues from both groups revealed noticeable disparities in cotyledons of RP as compared to normal placenta. Moreover, OXPHOS complex I specific activity was decreased in RP, and RT-qPCR analysis unveiled a significant reduction in transcript levels of 10 mtDNA-encoded protein genes. While COX3 and ATP8 genes showed no significant changes, ND6 increased in RP. Whereas, mtDNA copy number varied between animals but showed no statistically significant differences among groups. Retained placenta manifests alterations in the transcript levels of various mitochondrial genes, complex activity, and mtDNA content, potentially linked to heightened energy demands or mitochondrial insufficiency, posing an elevated risk. Overall, our study suggests a link between mitochondrial abnormalities, gene expression, and RP. This connection could influence the removal of fetal membranes by affecting energy supply, hormonal balance, and oxidative stress. This study also offers novel insights and serves as a valuable animal model for studying placental insufficiency in humans. Moving forward, comprehensive investigations are imperative to unravel underlying mechanisms and intricate roles of mitochondria in the context of RP, paving the way for targeted interventions to mitigate health, reproductive, and economic challenges in crossbred cattle.