Transcriptional profiling and pathway analysis reveal differences in pituitary gland function, morphology, and vascularization in chickens genetically selected for high or low body weight

Abstract

Background Though intensive genetic selection has led to extraordinary advances in growth rate and feed efficiency in production of meat-type chickens, endocrine processes controlling these traits are still poorly understood. The anterior pituitary gland is a central component of the neuroendocrine system and plays a key role in regulating important physiological processes that directly impact broiler production efficiency, though how differences in pituitary gland function contribute to various growth and body composition phenotypes is not fully understood. Results Global anterior pituitary gene expression was evaluated on post-hatch weeks 1, 3, 5, and 7 in male broiler chickens selected for high (HG) or low (LG) growth. Differentially expressed genes (DEGs) were analyzed with gene ontology categorization, self-organizing maps, gene interaction network determination, and upstream regulator identification to uncover novel pituitary genes and pathways contributing to differences in growth and body composition. A total of 263 genes were differentially expressed between HG and LG anterior pituitary glands ( P ≤ 0.05 for genetic line-by-age interaction or main effect of line; ≥1.6-fold difference between lines), including genes encoding four anterior pituitary hormones. Genes involved in signal transduction, transcriptional regulation, and vesicle-mediated transport were differentially expressed and are predicted to influence expression and secretion of pituitary hormones. DEGs involved in immune regulation provide evidence that inflammation and response to cellular stressors may compromise pituitary function in LG birds, affecting their ability to adequately produce pituitary hormones. Many DEGs were also predicted to function in processes that regulate organ morphology and angiogenesis, suggesting pituitary gland structure differs between the divergently selected lines. Conclusions The large number of DEGs within the anterior pituitary gland of birds selected for high or low body weight highlights the importance of this gland in regulating economically important traits such as growth and body composition in broiler chickens. Intracellular signaling, transcriptional regulation, and membrane trafficking are important cellular processes contributing to proper hormone production and secretion. The data also suggest that pituitary function is intimately tied to structure, and organization of the gland could influence hypothalamic and systemic metabolic inputs and delivery of hormones regulating growth and metabolism into peripheral circulation. Electronic supplementary material The online version of this article (10.1186/s12864-019-5670-9) contains supplementary material, which is available to authorized users.

The Effect of Commercial Genetic Selection on Somatotropic Gene Expression in Broilers: A Potential Role for Insulin-Like Growth Factor Binding Proteins in Regulating Broiler Growth and Body Composition

“…However, this increase was accompanied by either no change or inconsistent changes in liver IGF1, IGF2, and IGFR1 or a decrease in IGF1 and IGFR1 in breast muscle, suggesting that IGF1, IGF2, and IGFR1 production are not dependent on GH during late embryonic development. It has been suggested that the somatotropic axis is not fully established until after hatch (Ellestad et al, 2011;Ellestad et al, 2019), and this study provides further evidence that IGF production is likely not GH-dependent in the embryonic somatotropic axis.…”

“…This project was supported by funding from the College of Agricultural and Environmental Sciences, University of Georgia and Agriculture and Food Research Initiative Competitive Grants #2017-67015-26490 (TP andLE) and#2021-67034-35185 (LV andLE) from the USDA National Institute of Food and Agriculture.…”

“…Studies investigating levels of growth hormone (GH), which is classically thought to induce IGF secretion from the liver, also yield results inconsistent with the idea that increased somatotropic activity always leads to increased growth. Pituitary GH expression was greater between 3 and 7 weeks of age in male broilers with lower body weight as compared to those with a higher body weight ( Ellestad et al, 2019 ), and the percentage of GH-secreting cells in slow-growing chickens was greater at 5 weeks of age, though fast-growing embryos secreted more GH per hour ( Porter, 1998 ). Circulating GH was also found to be higher in chickens selected for egg production (layers) than those selected for meat production (broilers), despite layers growing slower and having lower body weights ( Reiprich et al, 1995 ).…”

Efektivitas Ekstrak Hipofisa Ayam Broiler (Gallus sp.) Terhadap Kinerja Reproduksi Dan Kelulushidupan Larva Ikan Lele Sangkuriang (Clarias sp.)

“…Ekstrak hipofisa ayam broiler selama ini diketahui mengandung hormon gonadotropin. Penelitian terbaru yang mengevaluasi ekspresi gen global dari ekstrak kelenjar hipofisis anterior ayam Gallus gallus melaporkan terdapat empat hormon hipofisis anterior yang terkandung dalam rangkaian gen yang diekspresikan berbeda-beda yaitu Thyroid Stimulating Hormone, Luteinizing Hormone, Follicle Stimulating Hormone, dan Growth Hormone (Ellestad et al, 2019).…”

Integrated mRNA and miRNA transcriptome analysis provides novel insights into the molecular mechanisms underlying goose pituitary development during the embryo-to-hatchling transition

“…In the chicken pituitary, the mRNA expression levels of growth hormone ( GH ) and prolactin ( PRL ) started to increase on embryonic day 16 ( E16 ) and E18, respectively ( Kansaku et al., 1994 ), while those of duck GH and IGF1 started to increase on E25 and E21, respectively ( Hu et al., 2015 ). Although the chicken pituitary transcriptome changes in the post-hatching development have been previously investigated ( Pritchett et al., 2017 ; Ellestad et al., 2019 ), there are still lack of studies on the avian pituitary developmental dynamics during the critical embryo-to-hatchling transition, especially in waterfowls.…”