Effects of water-deprivation stress on the expression of hepatic genes involved in blood pressure and stress response in chickens.

Water intake is crucial for livestock performance and welfare. Understanding the mechanisms underlying water homeostasis and stress responses during water shortages is essential for sustainable poultry production. This study examined how water deprivation (WD) affects hepatic genes related to blood pressure (BP) regulation and stress responses in broilers selected for high (HW) and low (LW) water efficiency. The genes analyzed included angiotensinogen (AGT), renin (REN), glucocorticoid receptor (GR), 11β-hydroxysteroid dehydrogenase-1 (11β-HSD1), and brain-derived neurotrophic factor (BDNF), measured in the liver. Birds from both lines underwent WD for 0, 12, and 24 h, with liver samples collected on days 38-40. The results showed that AGT and REN levels were higher in male than in female HW birds, indicating gender-specific expression of AGT and REN in the liver. The effects of 12 h and 24 h WD were more pronounced in HW than in LW birds, regardless of sex, implying a higher responsiveness of HW birds to WD stress. In both HW and LW, females exhibited higher GR and 11β-HSD1 levels than males. WD elevated GR and 11β-HSD1 expression in HW males but not in HW females, indicating a gender-specific stress response in the liver of HW birds. Conversely, LW females showed decreased GR levels after WD, and 11β-HSD1 was reduced after 24 h of WD in both sexes, suggesting a destructive stress response in LW birds. BDNF expression was three times higher in HW males than in HW females, with no significant gender difference in LW, suggesting a possible functional role for BDNF in the WD stress response and liver welfare. WD caused a time-dependent reduction in BDNF in both lines, indicating that water efficiency does not influence BDNF expression by gender. Overall, HW birds may demonstrate greater resilience in water homeostasis and BP regulation compared to LW birds. Hepatic BDNF expression levels in broilers may serve as a potential diagnostic marker of poultry health.