Transcriptome and metabolome reveal the mechanism of neuroendocrine regulation in ovarian development of broiler breeders

The long-term selection for meat has led to the poor egg production efficiency in broiler. In this study, we analyzed the transcriptional levels of hypothalamus and ovary during the pre-laying (PP) and laying periods (LP) of broiler breeders. By combining these with the levels of reproductive hormones and ovarian metabolism, to reveal the neuroendocrine control mechanism of ovarian development. Results showed that during LP, the number of LYFs, SYFs and WFs, the thickness of the granular cell layer, and the serum LH, FSH, P4 and E2 levels were significantly increased (P < 0.05). A total of 1188 and 2481 differentially expressed genes (DEGs) were detected in hypothalamus and ovary, respectively. 1972 significantly differentially metabolites (DMs) were detected in ovary. In hypothalamus, the expression of neuroendocrine regulatory genes such as TRH, AVT, VIP, and NYB in the Neuroactive ligand-receptor interaction pathway regulated the LH and FSH secretion via the HPG axis. In ovary, the promotion of GCs proliferation may occur through the glycerophospholipid metabolism pathway, which increased the thickness of the GCs layer. This helped to receive gonadotropin signals and increased P4 and E2 secretion. Meanwhile, the decreased expression levels of ovarian development inhibitory factors in the TGF-beta signaling pathway, including BMP2, BMP4, BMP15 and AMHR2, and the increased expression levels of MMPs, including MMP9, MMP11 and MMP13, may regulate the synthesis of metabolites associated with steroid hormone secretion and ovarian development, such as E2, E2-3S, 7 alpha-OH-DHEA, CHO and AD. These genes and metabolites may play an important role in HPG axis in regulating ovarian development.