The effect of pregnancy, heat stress and altrenogest supplementation on the porcine mid-luteal phase corpus luteum proteome

Functioning corpora lutea (CL) are required for establishment and maintenance of pregnancy in pigs. Disruptions of pregnancy and reproductive cyclicity due to heat stress (HS) result in substantial economic losses for the swine industry. The objectives of this study were to characterize the CL proteome during early pregnancy establishment, and identify differentially abundant proteins during pregnancy establishment affected by HS and altrenogest supplementation. Following synchronization and estrus detection, gilts (n = 41) were assigned to one of six treatment groups enabling comparisons to evaluate the effects of pregnancy (cyclic (C) or pregnant (P)), thermal environment (thermal neutral (TN) or HS), and within pregnant gilts, supplementation with altrenogest 15 mg/d (ALT) or without (CON). Gilts were exposed to the thermal treatment at 2 days post estrus (dpe) and began receiving ALT supplementation 3dpe. At 12dpe, animals were euthanized, CL (n = 3–4) from each gilt were collected, protein extracted, and subjected to label free liquid chromatography - tandem mass spectrometry (LC-MS/MS). Two separate analyses, one focused on the effect of pregnancy and environment, and the other on the effect of environment and ALT supplementation, were conducted that identified 1470 and 907 differentially abundant proteins, respectively. Differences between treatments identified that pregnancy, HS and ALT supplementation alter the CL proteome in ways that may influence CL function and regression. These included proteins involved in oxidoreductase activity (SOD1), translation and ribosomal activity, and metal ion binding (PGMRC1 and CYCS). An understanding of these effects could help improve reproductive performance in swine production.