Molecular mechanism of follicular development in laying hens based on the regulation of water metabolism.

Water metabolism is fundamental to sustaining physiological functions in living organisms and plays a particularly vital role in poultry, especially laying hens. It directly influences their health status and production performance. Follicular development, a crucial phase in the reproductive cycle of laying hens, is highly sensitive to water availability. Insufficient hydration can lead to increased stress, reduced synthesis of ovarian hormones, and impaired follicular maturation, while excessive hydration may disturb osmotic balance and interfere with normal follicle growth. Although existing studies have preliminarily demonstrated a link between water metabolism and follicular function, the molecular mechanisms - particularly those involving aquaporins, hormonal receptors, and intracellular signaling pathways - have not been comprehensively elucidated. By integrating molecular biology techniques, physiological indicators, and imaging analysis, this study reveals how water status regulates follicular development through the modulation of AQP1 and AQP3 expression, activity of follicle-stimulating hormone and luteinizing hormone receptors, and the MAPK/ERK and PI3K/Akt signaling pathways. It was found that water restriction significantly downregulated AQP1 and AQP3 expression and reduced FSH receptor and LH receptor activities. These molecular adjustments likely serve as adaptive responses to minimize water loss and preserve the stability of the follicular microenvironment. Meanwhile, water-restricted conditions enhanced MAPK/ERK activation and attenuated PI3K/Akt signaling, further influencing follicular growth. These findings contribute to a more refined understanding of the role of water metabolism in reproductive regulation and provide theoretical support for optimizing breeding strategies under hydration-related stress conditions.