Transcriptomic analysis of the porcine anterior pituitary gland during the peri-implantation period

Adaptation of the Porcine Pituitary Transcriptome, Spliceosome and Editome during Early Pregnancy

The physiological mechanisms of the porcine reproduction are relatively well-known. However, transcriptomic changes and the mechanisms accompanying transcription and translation processes in various reproductive organs, as well as their dependence on hormonal status, are still poorly understood. The aim of this study was to gain a principal understanding of alterations within the transcriptome, spliceosome and editome occurring in the pituitary of the domestic pig (Sus scrofa domestica L.), which controls basic physiological processes in the reproductive system. In this investigation, we performed extensive analyses of data obtained by high-throughput sequencing of RNA from the gilts' pituitary anterior lobes during embryo implantation and the mid-luteal phase of the estrous cycle. During analyses, we obtained detailed information on expression changes of 147 genes and 43 long noncoding RNAs, observed 784 alternative splicing events and also found the occurrence of 8729 allele-specific expression sites and 122 RNA editing events. The expression profiles of the selected 16 phenomena were confirmed by PCR or qPCR techniques. As a final result of functional meta-analysis, we acquired knowledge regarding intracellular pathways that induce changes in the processes accompanying transcription and translation regulation, which may induce modifications in the secretory activity of the porcine adenohypophyseal cells.

Transcriptome profile of the anterior pituitary gland in pigs during maternal recognition of pregnancy

The activity of the pituitary gland determines the success of female reproduction. The knowledge regarding the reproductive-status-related changes in the transcriptome of the porcine pituitary is limited. This study aimed to determine and compare the transcriptome profile of the pituitary gland collected from pigs during maternal recognition of pregnancy, i.e. on days 12-13 of pregnancy and during the respective days of the estrous cycle. Analysis indicated 482 differentially expressed genes (DEGs) with an FC > 1.5 (P < 0.05) in the pituitary of pregnant vs. estrous-cyclic pigs. Among them, 68 were up-regulated and 414 were down-regulated. The evaluated DEGs were annotated into 39 gene ontology (GO) biological process terms, 13 GO cellular component terms, and 10 GO molecular function terms. Among the evaluated DEGs were selected genes coding for proteins potentially involved in the regulation of early pregnancy in pigs and used for gene interaction analysis and validation of microarray results. An analysis of the relationships among DEGs in pituitaries collected during maternal recognition of pregnancy showed that some of them are connected with, for example, TGFβ signaling pathway, PRL synthesis, adipocytokines pathway and immune response during maternal recognition of pregnancy. These findings expand the knowledge regarding the molecular mechanisms appearing in the porcine pituitary during the maternal recognition period of pregnancy.

Effect of kisspeptin (KISS) and RFamide-related peptide-3 (RFRP-3) on the synthesis and secretion of FSH in vitro by pituitary cells in pigs

Kisspeptins (KISSs) and RFamide-related peptide-3 (RFRP-3) affect the synthesis and secretion of luteinizing hormone (LH) and modulate female reproductive processes. The presence of KISS and RFRP-3 in the porcine pituitary gland and their contribution to the regulation of follicle-stimulating hormone (FSH) synthesis and secretion is unknown. This study analyzed the presence of KISS and RFRP-3 in the pituitary of estrous-cyclic pigs on days 2 to 3, 10 to 11, 12 to 13, 15 to 16 and 19 to 20 and early pregnant pigs on days 10 to 11, 12 to 13 and 15 to 16, and evaluated the effect of KISS and RFRP-3 on β-Fsh mRNA expression and FSH secretion in vitro by pituitary cells collected on selected days of the estrous cycle. The cells were cultured in vitro and treated with KISS (10^-6 M, 10^-7 M) and RFRP-3 (10^-6 M, 10^-7 M) or gonadotropin-releasing hormone (GnRH; 100 ng/mL) alone and in combinations (4 h or 24 h). The relative abundance of Kiss and Rfrp-3 and their receptor mRNA transcripts, as well as the KISS and RFRP-3 proteins, were found in the pituitaries of estrous-cyclic and early pregnant pigs. KISS after 4 h increased the secretion of FSH in estrous cyclic pigs mostly during the early-luteal phase and luteolysis. RFRP-3 inhibited the synthesis and secretion of FSH in estrous-cyclic pigs on days 19 to 20 and the secretion of FSH on days 2 to 3 and 10 to 12 of the estrous cycle compared with GnRH-treated cells. KISS in co-treatment with GnRH after 24 h enhanced FSH release on days 2 to 3 and 15 to 16 of the estrous cycle. In conclusion, KISS and RFRP-3 systems are present in the pituitary of estrous-cyclic and pregnant pigs. In estrous-cyclic pigs, KISS and RFRP-3 may affect the synthesis and secretion of FSH by pituitary cells.