Ornithine decarboxylase influences granulosa cell proliferation and steroidogenesis: implications for ovarian regression in Wuding chickens.

Abstract

Follicular development critically determines egg-laying efficiency in poultry, a process precisely regulated by the equilibrium of granulosa cell (GC) proliferation, apoptosis, and steroidogenesis. Ornithine decarboxylase (ODC), the rate-limiting enzyme in polyamine biosynthesis, is a central regulator of cell proliferation and embryonic development. In this study, Wuding chickens, a breed exhibiting pronounced broodiness, were employed to elucidate ODC's role in follicular maturation and the transition from laying to broody state. Comprehensive analysis ofexpression across the hypothalamic-pituitary-gonadal (HPG) axis revealed significantly elevated levels in ovaries, pituitaries, and hypothalami of laying hens compared to broody hens. Primary GC cultures derived from Wuding chickens demonstrated that ODC promotes cell cycle progression viaupregulation and subsequent cyclin activation. Concurrently, ODC suppresses GC apoptosis by elevatingand suppressing, while enhancing steroidogenic capacity through coordinated regulation of key genes (,). Ourdata demonstrate that ODC modulates the expression ofandgenes, thereby maintaining elevated intracellular polyamine levels in GCs to sustain their proliferative activity. Collectively, ODC functions as a positive regulator of GC physiology in Wuding chickens, driving follicular development through dual mechanisms: c-MYC/cyclin-mediated proliferation and polyamine metabolic adaptation. These findings elucidate the metabolic and molecular mechanisms underlying the laying-to-broody transition in chickens.