Clustering of multi tissue transcriptomes in gilts with normal cyclicity or delayed puberty reveals genes related to pubertal development.

In gilts, puberty is marked by standing estrus in the presence of a boar. Delayed puberty (failure to display pubertal estrus) is a major reason for gilt removal. To investigate the physiological determinants underlying delayed puberty in gilts, transcriptomic data from tissues relevant to estrus and puberty, such as mediobasal hypothalamus, anterior pituitary gland, ovarian cortex, olfactory bulb, amygdala, and hippocampus were obtained from age-matched delayed puberty (n = 8) and cyclic control gilts at follicular phase (n = 8) and luteal phase (n = 8) of the estrous cycle. A gene expression module analysis via three-way gene x individual x tissue clustering using tensor decomposition identified pituitary and ovary gene modules contributing to regulation of pubertal development. Analysis of gene expression in the hypothalamic-pituitary-ovary axis identified reduced expression of hypothalamic genes critical for stimulating gonadotropin secretion (KISS1, TAC3) and reduced expression of LHB in the anterior pituitary of delayed puberty gilts compared to their cyclic counterparts. Consequently, LH-induced genes in the ovary important for folliculogenesis (OXTR, RUNX2, PTX3) were less expressed in delayed puberty gilts. Other intrafollicular genes (AHR, PTGS2, PTGFR, IGFBP7) and genes in the steroidogenesis pathways (STAR, CYP11A1) necessary to complete the ovulatory cascade were also less expressed in delayed puberty gilts. This is the first clustering of multi-tissue expression data from delayed puberty and cyclic gilts to identify genes differentially expressed in gilts of similar ages but at different levels of sexual development. A critical lack of gonadotropin support and reduced ovarian responsiveness underlie delayed puberty in gilts.