Insights into Transcriptomic Differences in Ovaries between Lambs and Adult Sheep after Superovulation Treatment

SIMPLE SUMMARY: By treating one-month old and adult Hu sheep with superovulation, we found that one-month-old lambs are able to produce more follicles than adult sheep. Nevertheless, our previous study revealed that oocytes derived from juvenile animals tend to be of poor quality, which means that they are less likely to mature and develop into embryos. By treating sheep with exogenous ovulation-inducing hormones, we compared the number of ovulation points and the serum hormone levels in both the lamb and adult groups. In order to reveal the mechanism of abnormal ovulation numbers and oocyte quality induced by hormone treatment in the lamb group, a high-throughput sequencing technique was used to identify the differences in long non-coding RNA (lncRNA) and messenger RNA (mRNA) expression in the ovaries in the lamb and adult groups. The conjoint analysis of lncRNA and mRNA revealed that OaPDGFR, XR_003588840.1, and its target gene OaLRP1, may be the key candidate genes in promoting the number of ovulations in lamb groups. ABSTRACT: Superovulation technology shows a great potential for shortening breeding time. Using the juvenile superovulation technology, juvenile animals can generate more follicles than adult animals. By sequencing using high-throughput methods, we studied and described differentially expressed (DE) long non-coding RNA (lncRNAs) and messenger RNAs (mRNAs) in the ovaries of young and adult sheep. Herein, 242 DE lncRNAs and 3150 DE mRNAs were screened. Through GO and KEGG analyses, we obtained genes related to ovarian/follicle development and ovulation in DE mRNAs, including OaFSHR, OaLHCGR, OaLDLR, OaZP3, OaSCARB1, and OaPDGFRA; through lncRNA-mRNA correlation analysis, we found that genes associated with ovarian/follicle development or ovulation include: XR_003585520.1, MSTRG.15652.1, XR_003588840.1, and their paired genes PDGFC, LRP5, and LRP1. We observed a synergistic effect between PDGFR and LRP1. PDGFR may play a leading role compared with LRP1. The induced LHCGR in lambs is higher than in adult sheep, showing more sensitivity to LH. The release of the oocytes was stimulated. Among the three lncRNAs, we found that XR_003588840.1 was significantly different and might perform a regulatory role in ovarian/follicle growth or ovulation.