How oral cancer is taught: a scoping review.

The ovary is the most vital reproductive organ in female mammals. It mainly produces developmentally totipotent oocytes. It also secretes steroid hormones [], regulating estrous cycle activities [,]. Arguably, it is involved in nearly all aspects of the reproductive process in sows. Therefore, ovarian function is the key factor influencing sow reproductive performance. Currently, the ceRNA research idea has been applied to studies examining differences in the longissimus dorsi muscle of various pig breeds, differences in porcine skeletal muscle, and pork fat deposition [,,]. However, there is a scarcity of relevant research; in fact, the estrus process in sows is governed by a complex and tightly regulated molecular network, which is collectively influenced by numerous genes and transcription factors, with non-coding RNAs playing a vital role in this regulation []. These non-coding RNAs include long non-coding RNAs (lncRNAs), microRNAs (miRNAs), circular RNAs (circRNAs), and others []. Salmena et al. [] introduced the “competing endogenous RNA (ceRNA)” hypothesis, describing a molecular mechanism where non-coding RNAs and protein-coding genes competitively bind miRNAs via miRNA response elements (MREs). Both lncRNAs [] and circRNAs [] can serve as miRNA sponges, absorbing miRNAs and functioning as ceRNAs, thereby affecting miRNA activity, regulating mRNA expression, and ultimately influencing various biological processes [,]. CeRNA regulatory networks participate in multiple biological processes, especially reproduction and development. Previous studies have reported their functions in regulating gonadal development in golden pompano [], as well as reproductive performance in Hy-Line Brown laying hens [] and goats () []. Accumulating evidence also reveals that ceRNA pathways mediate estrus regulation in ovarian tissues []. However, few studies are focusing on the role of ceRNAs in gilt estrus traits; therefore, it is necessary to identify key mRNAs and non-coding RNAs that regulate the estrous cycle in gilts, thereby establishing a theoretical foundation for a deeper understanding of how these RNAs mediate target genes to regulate estrus. Abnormal estrus, including anestrus (silent estrus representing a form of apparent anestrus) and persistent estrus, arises from disruption of the hypothalamic-pituitary-ovarian endocrine cascade []. Deficiencies in the preovulatory luteinizing hormone surge prevent normal ovulation, leading to persistent anovulatory follicles and follicular cyst formation in gilts [,]. Disturbed steroid secretion further impairs behavioral estrus signals, generating silent estrus: functional ovulation occurs without visible estrous manifestations []. Clinically, these disorders extend non-productive days, decrease farrowing rates, and increase herd elimination costs, posing substantial threats to swine reproductive efficiency []. The high rearing costs of gilts and the occurrence of anestrus are primary reasons for their large-scale culling, leading to substantial economic losses. Therefore, this study conducted whole-transcriptome sequencing of ovarian tissues from NE gilts and AE gilts with follicular cyst-associated silent estrus to establish a ceRNA regulatory network. This study aimed to screen key mRNAs and non-coding RNAs associated with the regulation of silent estrus by follicular cysts in gilts, laying a preliminary transcriptomic reference for future research on ovarian estrous regulatory networks.