Transcriptomic Changes in Broiler Chicken Hypothalamus during Growth and Development

Abstract

The hypothalamus plays an overarching role that is reflected in the physiological processes observed in the entire organism. The hypothalamus regulates selected metabolic processes and activities of the autonomic nervous system. The avian hypothalamus due to the structural complexity is not well described and has a slightly different function than the mammalian hypothalamus that is the subject of numerous studies. The present study evaluated activities of hypothalamic genes in fast-growing chickens during development (at the 1st day and 3rd and 6th weeks after hatching). The hypothalamic transcriptomes for 3- and 6-week-old cockerels were analysed using an RNA sequencing method in next-generation sequencing (NGS) technology. The differentially expressed gene analysis was conducted using DESeq2 software. In younger 22-day-old cockerels, 389 genes showed higher expression (fold change > 1.5) than that in 45-day-old birds. These genes played a role in several biological processes because they encoded proteins involved in integrin signalling, regulation of hormone levels, camera-type eye development, and blood vessel development. Moreover, surprisingly in the hypothalamus of 3-week-old cockerels, transcripts were identified for proteins involved in both anorexigenic (POMC, NMU) and orexigenic (PMCH, ALDH1A1, LPL, and GHRH) pathways. The RNA-seq results were confirmed by qPCR methods. In summary, the intensive growth of 3-week-old chickens was reflected in hypothalamic activities because the genes associated with the somatotropin axis and regulation of satiety centre showed increased expression.

Thyrotropin-Releasing Hormone (TRH) and Somatostatin (SST), but not Growth Hormone-Releasing Hormone (GHRH) nor Ghrelin (GHRL), Regulate Expression and Release of Immune Growth Hormone (GH) from Chicken Bursal B-Lymphocyte Cultures

“…Initially, we explored whether GH and its canonical secretagogues and their respective receptors were expressed in chicken bursal B-lymphocyte cultures by RT-PCR, in comparison with hypothalamus, pituitary, and liver, respectively. As expected, the expression of GHRH, TRH, ghrelin, and SST mRNAs were found in the chicken hypothalamus used as control, confirming previous results regarding their hypothalamic production in several species, including avian models [36,37]. Additionally, the expression of GHRH-R, TRH-R, GHS-R1a, SST-Rs, and GH-R mRNAs were observed in the chicken pituitary control, in concordance with previous reports [38][39][40][41][42]; and GH-R mRNA was found in the liver.…”

Identification of candidate genes and regulatory factors related to growth rate through hypothalamus transcriptome analyses in broiler chickens

“…The birds were euthanized by decapitation after electrical stunning (150 mA, frequency of 200 Hz for 4 s). Then, the whole chicken hypothalamus was collected and stored as was described by Piórkowska et al [19]. Carcass and growth traits were measured following the method described by Połtowicz et al [51].…”

“…RNA from hypothalamus was isolated, as was described by Piórkowska et al [19]. The quality and concentration of RNA were measured using a TapeStation2200 Fig.…”

“…In turn, Han et al [18] using analysis of miRNAom suggested that miRNAs play an essential role in the hypothalamus for timing the rapid development of chicken gonads. While Piórkowska et al [19] used the RNA-seq method to pinpoint the hypothalamic gene expression changes during postnatal development in broiler chickens.…”

L-Citrulline Influences the Body Temperature, Heat Shock Response and Nitric Oxide Regeneration of Broilers Under Thermoneutral and Heat Stress Condition

“…Chickens were sacrificed by decapitation and exsanguination after 5 h HS, and tissue samples were excised, weighed, snap-frozen in liquid nitrogen, and stored at −80°C for further studies. The hypothalamus was dissected from the brain using mini tweezers as previously described ( Piorkowska et al, 2018 ). Relative organ weight was computed as organ weight/body weight of chicken x 100.…”