Association of relative expression of HSD11B-1 and HSD11B-2 with pregnancy status in sheep

Livestock profitability hinges on reproductive efficiency, which can be significantly affected by factors such as extreme weather conditions. Early and accurate pregnancy detection is vital for optimizing reproductive physiology and ensuring economic sustainability. This study employed quantitative Real-Time Polymerase Chain Reaction (qRT-PCR) to evaluate the expression levels of HSD11B-1 and HSD11B-2 genes in peripheral blood mononuclear cells (PBMCs) from five sheep breeds: Barki, Rahmani, Rahmani x Barki crossbred, Awassi, and Ossimi. A total of 500 ewes, with 100 from each breed, and 75 rams (15 from each breed) were selected for detailed analysis based on uniform age (21.00 ± 0.75 months) and weight (45.00 ± 3.00 kg). Blood samples were collected on specified days ranging from day 9 post-mating to prepartum luteolysis to analyze gene expression associated with different gestational stages.

The current analysis revealed significantly elevated levels of HSD11B-1 and HSD11B-2 gene expression in pregnant ewes compared to non-pregnant and control groups across all breeds. For the HSD11B-1 gene, expression levels progressively increased and peaked between days 35 and 40 post-mating (p < 0.001), with all breeds showing significant fold-changes during this period. Rahmani x Barki crossbred demonstrated the highest fold-changes for this gene. Both HSD11B-1 and HSD11B-2 exhibited a significant increase from day 11 to day 18 post-mating (p < 0.01). However, their expression patterns differed during gestation. HSD11B-1 recorded its highest expression levels (p < 0.001) during mid-gestation (days 35-45), while HSD11B-2 peaked earlier (p < 0.001), particularly during the post-implantation phase (days 18-25).

To the best of our knowledge, this study is the first to report a significant upregulation of both genes as early as day 12 post-mating, providing a new benchmark for early pregnancy detection, which previously focused on day 14. This insight into gene expression patterns provides valuable information for reproductive biology and may inform future breeding and management practices aimed at optimizing reproductive success in sheep.