Effect of enhanced early life nutrition on the molecular regulation of anterior pituitary function in Holstein Friesian bull calves

Abstract

Abstract Enhanced early-life nutrition is known to induce precocious reproductive development in the bull calf, mediated through gonadotropin releasing hormone (GnRH) stimulated gonadotropin pulsatility in the anterior pituitary gland. The objective of this study was to evaluate transcriptomic and proteomic responses within the anterior pituitary of Holstein–Friesian bull calves offered different planes of nutrition during early life. Bull calves were offered either a high (HI; n = 15) or moderate (MOD; n = 15) plane of nutrition between 2–12 weeks of age and subsequently euthanised at 12 weeks of age. The anterior pituitary tissue was harvested from all calves and miRNAseq, mRNAseq and proteomic analyses undertaken. High diet calves displayed greater growth rates compared to MOD calves (P < 0.001). Overall, 37 mRNAs and 5 miRNAs were differentially expressed between treatment groups (FDR < 0.1). Reduced expression of miR-205 together with greater expression of specific target mRNA genes (PCSK1, SERPINA1, CARTPT) in the HI calves suggested a relationship between these mRNA and miRNA. Furthermore, co-regulatory network analysis of the proteomic data revealed interactions between PCSK1, SERPINA1 and CARTPT, and proteins involved in cellular proliferation, metabolism and GnRH signalling, highlighting a role for these proteins in mediating the intersection between enhanced metabolic status with reproductive signalling in young bull calves.