Hormonal Signaling and Follicular Regulation in Normal and Miniature Pigs During Corpus Luteum Regression

Area of Science:

• Comparative reproductive biology
• Endocrinology and physiology

Background:

• Miniature pigs are valuable biomedical models, but their reproductive characteristics, especially during corpus luteum regression, are not well understood.
• Differences in follicular development, hormonal pathways, and vascularization may explain lower fertility in minipigs versus conventional pigs.

Purpose of the Study:

• To compare follicular development and hormonal signaling between conventional and miniature pigs after corpus luteum formation.
• To identify molecular and morphological differences affecting reproductive efficiency in minipigs.

Main Methods:

• Histological staining, immunofluorescence, hormonal assays, and transcriptomic profiling (microarray) were used.
• Expression of key hormones (VEGF, mTOR, LH, FSH, E2, PAPP-A) and apoptosis markers was evaluated.
• Differential gene expression analysis and Gene Ontology (GO) categorization were performed.

Main Results:

• Minipigs had smaller follicles, reduced vascularization, and lower VEGF/MMP activity than conventional pigs.
• Conventional pigs showed higher LH and PAPP-A, while minipigs had elevated E2 and FSH.
• Conventional pigs exhibited greater upregulation of cell-survival and angiogenesis genes (including IGF pathways); minipigs showed increased apoptosis and poor extracellular matrix remodeling.

Conclusions:

• Minipigs exhibit impaired follicular remodeling and weaker hormonal signaling post-corpus luteum formation, contributing to reduced reproductive efficiency.
• Understanding these species-specific differences is vital for optimizing breeding strategies and fertility management in minipigs.
• These insights enhance the translational reliability of minipigs as biomedical models.