Relative abundance and localization of interferon-stimulated gene 15 mRNA transcript in intra- and extra-uterine tissues during the early stages of pregnancy in sheep.

The aim of this study was to investigate relative abundance and localization of ISG15 mRNA transcript in intra-uterine (trophoblast, endometrium) and extra-uterine (hypothalamus, anterior pituitary, corpus luteum) tissues before and during the period of conceptus implantation. Multiparous ewes (n = 16) were randomly allotted into four groups: pregnant or estrous cyclic on days of 12 and 16 (n = 4 per group) following estrus. Relative abundances of ISG15 mRNA transcript were determined in the endometrium, corpus luteum, hypothalamus, and anterior-pituitary using real time quantitative PCR. Localization of ISG15 mRNA transcript was evaluated using in situ hybridization. The presence of ISG15 mRNA transcript was only visualized in intra-uterine tissues including the endometrium and trophoblast on day 12 of pregnancy. The ISG15 mRNA transcript was detected in all tissues evaluated on day 16 of pregnancy. The abundance of ISG15 mRNA transcript was greater in the endometrium on day 12 of pregnancy than at other days when evaluations occurred while in all other tissues except the hypothalamus there were large abundances of ISG15 mRNA on day 16 of pregnancy. It is concluded that the ISG15 mRNA transcript is only present in intra-uterine tissues before conceptus implantation. The ISG15 mRNA transcript, however, is present in extra-uterine tissues of ewes during implantation probably due to an increased amount of interferon-tau in blood circulation that is produced by the developing embryo. Results also indicate, for the first time, that pregnancy is associated with an intra-hypothalamus and anterior pituitary increased abundance of ISG15 mRNA transcript in ewes.

Expression patterns of Toll-like receptors in the ovine corpus luteum during the early pregnancy and prostaglandin F2α-induced luteolysis.

The aim of this study was to elucidate the expression profiles of Toll-like receptors (TLRs) in the ovine corpus luteum (CL) during early pregnancy and prostaglandin F2α (PGF2α)-induced luteolysis. For this purpose, multiparous Anatolian Merino ewes were selected and randomly allotted into cyclic (including those in the induced luteolysis group, n = 20) and pregnant (n = 12) groups. All of the ewes were scheduled to be slaughtered for predetermined days/hour during the estrous cycle, early pregnancy, and PGF2α induced luteolysis. The CLs were collected from both cyclic and pregnant ewes on days 12 (C12 and P12; n = 8) and 16 (C16 and P16; n = 8) and pregnant ewes on day 22 (P22; n = 4). For the induced luteolysis model, ewes were injected with PGF2α on day 12 of the estrous cycle and CLs were collected at 1 h (PG1h; n = 4), 4 h (PG4h; n = 4), and 16 h (PG16h, n = 4) after injection. Quantitative polymerase chain reaction (qPCR) was used to evaluate the expression profiles of TLR2, TLR4, TLR6, TLR8, and TLR10, while free-floating in situ hybridization and immunohistochemistry were used to define the spatial localization of TLR2, TLR4, and TLR7 in the CL. Data were then analyzed by one-way ANOVA and were considered statistically significant when P values were lower than 0.05. Expression of TLR2 was upregulated in both early and late stages of luteolysis (P < .05). An upregulation of TLR4 was detected at PG16h, while TLR6 was decreased at PG4h (P < .05). Expression of TLR7 and TLR8 was significantly increased during early pregnancy, at both PG16h and regressed groups (C16, P < .05). In contrast, TLR10 was downregulated during PGF2α-induced luteolysis and on P16 (P < .05). TLR4 and TLR7 proteins were particularly localized in endothelial cells on C12/PG0h, but prominent signals corresponding to TLR4 and TLR7 were detected in luteal cells at PG16h. The results suggest an involvement of TLRs in the luteolytic mechanism in ovine CL, as indicated by differential expression levels of TLRs during PGF2α-induced luteolysis. Moreover, the present study indicates that early pregnancy-mediated changes in TLR expression in the CL may contribute to the establishment and maintenance of ovine pregnancy.