Endocrine Regulation of Reproductive Traits in Avian Species

Avian reproduction is orchestrated by a finely tuned endocrine network centred on the hypothalamic–pituitary–gonadal (HPG) axis. Gonadotropin-releasing hormone synthesised in the hypothalamus drives the pituitary secretion of luteinising hormone and follicle-stimulating hormone, which in turn regulate ovarian follicle development, steroid hormone synthesis and ovulation. Prolactin assumes a pivotal role in the onset and maintenance of broodiness, suppressing further follicular maturation and inducing incubation behaviour. Oestrogens and progesterone modulate secondary sexual characteristics, oviduct morphology and egg formation, while androgens contribute to mate-attracting behaviours and sperm maturation in males. Seasonal breeders integrate photoperiodic cues via melatonin pathways to time reproduction, and neuropeptides such as vasoactive intestinal peptide and gonadotropin-inhibitory hormone impart additional layers of control. At the ovarian level, granulosa and theca cells communicate through paracrine and autocrine signals, balancing proliferation, differentiation and apoptosis to determine clutch size and egg quality. Environmental stressors including oxidative challenge can disrupt this equilibrium, precipitating impaired fertility or altered broodiness. Understanding these interconnections has profound implications for poultry production, wild-bird conservation and the management of species threatened by climate-driven alterations in breeding phenology.

Research from Nature Portfolio

Whole-transcriptome profiling of atrophic ovaries in broody chickens has revealed a comprehensive set of differentially expressed protein-coding genes, microRNAs and long non-coding RNAs that converge on pathways of cell proliferation, apoptosis and steroid metabolism. Integration of competing endogenous RNA networks highlighted key regulators of ovarian regression during broodiness, including candidates that govern extracellular matrix remodelling and hormone biosynthesis.

Transcriptomic comparison of follicles from egg-laying and broody Zhedong white geese demonstrated marked shifts in the expression of transcription factors and hormone-related genes. Up-regulation of autophagy-associated transcripts and altered progesterone and oestradiol concentrations in broody follicles pointed to a coordinated hormone-autophagy module that drives follicular atresia and enforces the cessation of laying.

Endocrine Regulation of Reproductive Traits in Avian Species publication trend

The graph below shows the total number of articles in endocrine regulation of reproductive traits in avian species across all publications each year (not limited to Nature Index journals).

Technical terms

Hypothalamic–pituitary–gonadal (HPG) axis: The endocrine pathway linking the hypothalamus, pituitary gland and gonads that governs reproductive function.

Gonadotropins: Pituitary hormones (luteinising hormone and follicle-stimulating hormone) that stimulate gonadal steroidogenesis and gametogenesis.

Prolactin: A pituitary hormone critical for the initiation and maintenance of broody behaviour and incubation in birds.

Granulosa cells: Ovarian somatic cells surrounding developing oocytes, essential for steroid hormone production and follicle maturation.

Autophagy: A cellular degradation process that recycles cytoplasmic components, implicated in follicular atresia during broodiness.

Broodiness: An intrinsic behavioural and physiological state in female birds characterised by nesting, incubation and suppression of egg laying.

References

1. Whole-transcriptome analysis of atrophic ovaries in broody chickens reveals regulatory pathways associated with proliferation and apoptosis. Scientific Reports (2018).
2. Transcriptome analysis of follicles reveals the importance of autophagy and hormones in regulating broodiness of Zhedong white goose. Scientific Reports (2016).
3. Pituitary transcriptome profile from laying period to incubation period of Changshun green-shell laying hens. BMC Genomics (2024).
4. Effects of Oxidative Stress on the Autophagy and Apoptosis of Granulosa Cells in Broody Geese. International Journal of Molecular Sciences (2023).