Background: Exposure to elevated ambient temperatures causes significant challenges for poultry production. The activation of the heat shock response, characterized by the upregulation of heat shock proteins, is one of the primary cellular strategies to relieve thermal stress. Emerging evidence also suggests that serotonin plays a regulatory role in heat shock proteins gene expression and enhances cellular stress resilience.
Objectives: The purpose of this study is to investigate the role of serotonin in regulation the expression of heat shock proteins 70 and 90 in the liver and heart tissues of Ross broiler embryos exposed to heat stress. Additionally, the study evaluated serotonin’s potential as an anti-stress agent.
Methods: A total of 120 fertilized eggs were randomly assigned to two groups: control and serotonin-treated (20 µg/egg). Serotonin or saline was injected into the albumen before incubation. On day 13, the embryos were further divided and exposed to either normal or elevated temperatures. The heat stress regimen began for 2 h at 39.5°C and was increased by 2 h daily until it reached 10 h by day 17. On day 18, tissue samples were collected for gene expression analysis.
Results: Heat stress significantly increased and decreased the expression of heat shock protein 70 and 90 in heart tissue (P<0.05). In ovo serotonin injection led to a significant upregulation of heat shock proteins 70 and 90 in heart tissue, particularly under heat stress (P<0.05). No significant changes in heat shock protein 70 expression were observed in liver tissue (P > 0.05). However, there was a significant increase in heat shock protein 90 expression in the serotonin-treated heat-stressed group (P<0.05).
Conclusions: Serotonin modulates heat shock proteins expression under heat stress conditions in Ross broiler embryos. Based on the existing evidence, this is the first report indicating that in ovo serotonin administration enhances cellular stress responses, particularly in heart tissue. These findings demonstrate a potential strategy for mitigating the effects of heat stress in poultry through serotonin-based interventions.