Reproduction Abstracts

Low birth weight observed in the ‘runt’ piglet of the litter compared to its siblings has severe consequences for neonatal and adult development that cannot be remedied post-natally. This study compared the expression of a number of candidates hypothesised to be involved in angiogenesis and placental attachment in porcine endometrial samples.

Endometrial tissues supplying the smallest and normal-sized foetuses were collected from large white landrace gilts at gestational day (GD) 30 (n=4) and 60 (n=4). QPCR for secreted phosphoprotein 1 (SPP1), endometrial heparinase (HPSE), vascular endothelial growth factor A (VEGFA), uteroferrin (ACP5), and hypoxia-inducible factor 1A (HIF1A) was carried out and the relative expression of each candidate analysed. SPP1 protein localisation was quantified in paraffin embedded samples using immunofluorescence.

Relative expression of ACP5 and SPP1 was increased and HPSE was decreased at GD60 (3.26±0.57; 2.52±0.32; and 0.92±0.25, respectively; mean±S.E.M.) compared to GD30 (0.29±0.08; 0.27±0.07; and 3.20±0.74; FPr ≤0.002). No size related differences in the expression of any of the genes was detected. Immunofluorescence revealed SPP1 protein is highly expressed in the glandular epithelium at GD60 (9.91%±1.08), with little expression detected at GD30 (0.15%±0.07; FPr <0.001). Endometrial samples supplying small foetuses had decreased SPP1 expression per glandular epithelium compared to those supplying normal foetuses. These findings suggest that temporal changes in endometrial expression of these candidates during gestation occurs, but is not altered in endometrial tissue supplying smaller foetuses. To fully understand the mechanisms governing growth retardation, both the endometrial and placental contribution must be thoroughly investigated.

Funded by BBSRC and Edinburgh University.