Investigation on Hypothalamic GABAergic system difference of local and Leghorn hens based on RNA-Seq dataset

Abstract

Objective: g-Aminobutyric acid (GABA) is a non-protein amino acid synthesized by decarboxylation of glutamate by the enzyme glutamic acid decarboxylase. The central nervous system (CNS) contains uniquely high concentrations of GABA, and GABA serves as a major inhibitory neurotransmitter. The biological effects of the amino acid neurotransmitter GABA are mediated by ionotropic GABA-A receptors, a family of ion channels, and by the metabotropic GABA-B receptor, a receptor coupled to the inhibitory G-protein. Gene expression Status of GABAergic circuit is changed under different physiological conditions. Broodiness is one of those conditions. Investigation on high broodiness occurrence breed and breed without broodiness would be able to declare this discrepancy of different in egg lying and broodiness condition. Material and methods: available dataset of hypothalamus gene expression were downloaded from NCBI (http://www.ncbi.nlm.- nih.gov/sra/SRP082125). The transcriptional profiling of hypothalamus samples from leghorn and local hen in non-broodiness and broodiness condition respectively was carried out at 2 samples for treated and 2 samples for control group. The quality control of sequencing reads was carried out by FastQC software. Filtered reads were evaluated with FastQC. String database was used for the retrieval of interacting genes and Cytoscape software was used to visualize the network. Kyoto encyclopedia of genes and genomes (KEGG) pathway analysis. Results: In hypothalamus of non-broodiness and broodiness hens 2943 genes was expressed. After searching gene ID and analyzing 7 genes was identified as a GABAergic pathway. two enzymes involved in converting Glutamat to GABA, including GAD1 and GAD2. Both of them had down-regulation of expression in local hen compared to Leghorn hens. Gene reduction of GABAA, G and B receptors, gene increase expression of GABAA subunit of Pi and GABAC subunit of R1 was observed in local hen compared to Leghorn hens. Conclusion: with investigation on transcription of GABAergic pathway of local and Leghorn hens, both GABA synthetic enzymes and GABA receptors showed significant difference. This showed more GABA receptor and GABA synthetic enzymes gene expression in lying hen and probably with survey of GABAergic pathway during different phase of egg production, more noticeable result would be declared.

Keywords

• laying hen
• broodiness
• hypothalamus
• gaba
• gene expression