Expression of obesity gene and obesity gene long form receptor in endometrium of Yorkshire sows during embryo implantation

Abstract

There is accumulating evidence that leptin may be directly involved in mammalian reproduction, however, the potential role of obesity gene/obesity gene long form receptor (ob/ob-Rb) system in porcine implantation is poorly understood. To further confirm this role, mRNA and protein expression of ob/ob-Rb in implantation site and inter-implantation sites of porcine uterus on pregnancy day 13, 18 and 24 were compared in this study. Ob mRNA level went up with the advance of pregnancy and was higher in implantation site than inter-implantation site (P < 0.05). But ob-Rb mRNA, which was negative-regulated by leptin, went down with the advance of pregnancy and lessened in implantation site compared with inter-implantation site (P < 0.05). During the three implantation phase, leptin protein peaked at day 18 pregnancy (P < 0.05) and leptin protein at implantation site were always higher than inter-implantation site (P < 0.05). The higher ob-Rb protein in implantation site compared with inter-implantation site (P < 0.05) only appeared at day 18 pregnancy. Localization of ob/ob-Rb protein in porcine uterus was assayed using immunohistochemistry and found that ob/ob-Rb protein mainly located in luminal epithelium and glandular epithelium in pregnant pigs, but distinct immune-staining of leptin also detected in stroma in non-pregnancy porcine uterus except for luminal epithelium and glandular epithelium. In conclusion, the peak of leptin and the peak of ob-Rb protein in implantation site specifically appeared on day 18 pregnancy of pig. Another funning discovery is ob-Rb mRNA in porcine endometrium was mainly negative-regulated by leptin. The space-time difference of gene and protein expression for ob/ob-Rb confirmed ob/ob-Rb system role as delicate regulator of porcine implantation process.

Differential gene expression of Eph‐ephrin A1 and LEPR‐LEP with high or low number of embryos in pigs during implantation

“…EphA1 mRNA expression was also found at the endometrial attachment site of Yorkshire sows during embryo implantation (Fu, Fu, Ren, et al., ; Fu, Fu, & Wang, ). In Yorkshire sows, there were significant mRNA expressions of LEPR and LEP at the embryonic attachment and endometrial interattachment site (Wang et al., ). In Suzhong sows, at the endometrial attachment site displayed the highest mRNA expression of LEPR among all 22 tissues (Fu et al., ).…”

“…The available data have identified some genes that regulate embryo attachment in pigs, and these genes include the following: peroxisome proliferator‐activated receptor γ (PPARγ) (Wang, Kong, Hu, Fu, & Wang, ), Muc1 (Chen, Fu, & Wang, ), erythropoietin‐producing hepatocellular receptor–ligand (Eph‐ephrin) system (Fu, Fu, Ren, Chen, & Wang, ), obesity gene (or known as leptin or LEP) (Wang, Fu, & Wang, ) and leptin receptor (LEPR) (Fu, Li, Li, Fang, & Ren, ). Among these genes, Eph‐ephrin A1 is an important member of the Eph‐ephrin system, which plays an important role in a variety of developmental processes including cell migration, adhesion, vasculogenesis and neuronal plasticity through cell‐to‐cell communication (Kania & Klein, ; Lim, Bae, Bazer, & Song, ).…”

Investigation of Eph‐ephrin A1 in the regulation of embryo implantation in sows

“…Embryo implantation, also known as embryo attachment, is critical for successful pregnancies in pigs. Approximately 20%–30% of embryonic/foetal death occurred during this period (Su et al, ; Wang, Fu, & Wang, ; Wu, Wang, Li, Fu, & Zhao, ), which is the main cause of piglet loss in the pig industry (Fu et al, ; Geisert & Schmitt, ; Lin et al, ). Reducing piglet losses and increasing litter sizes are major concerns of swine producers, while the embryo implantation is an important factor affecting the litter size and the litter weight of pigs (Fu, Li, Li, Fang, & Ren, ).…”

Presence of Leptin and Its Receptor in the Hypothalamus, Uterus and Ovaries of Swine Females Culled with Distinct Ovarian Statuses and Parities

“…Additionally, leptin was detected in the luminal and glandular epithelia of the uterus of pregnant sows, downregulating the expression of mRNA of its receptor (Wang et al. ). Therefore, the levels of leptin in the hypothalamus may downregulate the expression of ObR‐b in the uterus, depending on the phase of the oestrous cycle (Smolinska et al.…”

“…), whereas such expression is downregulated by leptin, in swine (Wang et al. ). In swine ovaries, leptin is increasingly detected in developing follicles and reaches its greatest concentration in recently formed corpora lutea (Gregoraszczuk et al.…”