Chronic heat stress affects numerous physiological and behavioral mechanisms. Epigenetic changes following prolonged cyclic heat stress, creating new opportunities for molecular biology research. One of these changes involves monoamines, such as serotonin, epinephrine, norepinephrine, dopamine, and their transmission. Broiler chickens are highly susceptible to heat stress, and their hearts become insufficient during the growth phase, leading to hypertrophy of the left heart. RNA-seq data were obtained from NCBI with accession number SRP082125. The expression level of genes was determined with DESeq2 packages. Gene Ontology qualification, including biological processes, cellular components, and molecular role (MF), was performed from the Gene Ontology Resource. Cyclic heat stress in broilers significantly altered monoamine receptor expression. Twenty-nine genes of the monoamine pathway changed their expression in the left heart. Significant downregulation of expression was statistically associated with the ADRB1, HTR2A, and PNMT genes and upregulation of the MAOA gene (P<0.01). STRING database was used to construct the protein-protein interaction network; based on network analysis, the HTR2C, HTR2A, and HTR5A genes were identified as the major nodal genes in the network followed by MAOA, DRD2, DRD5, HTR1B, DRD1, DRD3, and HTR2B genes occupying the second important place in the network module. In conclusion, heat stress treatment prevented cardiac hypertrophy and altered the expression of monoamine genes. This would imply that monoamine transmission plays an important role in the development of cardiac hypertrophy, and that cyclic-chronic heat treatment modulates the cardiac monoaminergic system. These molecular biomarkers could be useful for screening, diagnosis, and treatment of cardiac hypertrophy.
Keywords: Broiler; Gene expression; Heart; Heat stress; Hypertrophy; Monoamine.