Lightning Talk + Poster ESA-SRB-NZSE-CaSR 2026 in conjunction with ENSA

Reproductive ageing disrupts cumulus-oocyte NAD⁺ homeostasis (144052)

Bettina P Mihalas 1 , Denise Lin 1 , Sonia Bustamante 2 , Russell Pickford 2 , Emily R Frost 1 , Ananya Vuyyuru 1 , Derek Wong 1 , Michael J Bertoldo 1 3 , Lindsay E Wu 3 , Robert B Gilchrist 1
  1. Discipline of Women’s Health, School of Clinical Medicine, University of New South Wales, Sydney, NSW, Australia
  2. Bioanalytical Mass Spectrometry Facility, Mark Wainwright Analytical Centre, University of New South Wales, Sydney, NSW, Australia
  3. School of Biomedical Sciences, University of New South Wales Sydney, Sydney, NSW, Australia

Background
The age-related decline in oocyte nicotinamide adenine dinucleotide (NAD⁺) is associated with impaired redox metabolism and reduced fertility. However, the cause of declining oocyte NAD⁺ remains unresolved. Given the central role of cumulus-cells in oocyte metabolism, we hypothesised that reproductive ageing disrupts cumulus–oocyte metabolic coupling, impairing oocyte NAD⁺ homeostasis.

Methods
Oocytes and cumulus-cells from cumulus–oocyte complexes (COCs) were analysed by targeted LC-MS/MS for NAD⁺/adenine metabolites, from young and reproductively aged mice, upon disrupted cumulus communication (carbenoxolone;CBX) or mechanical denudation (denuded oocytes; DO), or upon acute H₂O₂ exposure, ± the NAD⁺ precursor nicotinamide mononucleotide (NMN). Deuterium-labelled NMN (d4-NMN) LC-MS/MS tracing assessed NAD⁺ synthesis. Redox outcomes were assessed using CM-H₂DCFDA (reactive oxygen species;ROS), monochlorobimane (glutathione), and JC-1 (mitochondrial membrane potential). Cumulus-cells from 23 fertility patients were also analysed.

Results
We identified altered NAD⁺ metabolites in mouse oocytes (NADP, p=0.029; NADPH, p=0.024) and cumulus-cells (NAD⁺, p=0.006; NADP, p=0.007) with age, and in aged human cumulus-cells (NAM, p=0.004; meNAM, p=0.049). Disrupted COC communication impaired oocyte NAD⁺ homeostasis, increasing oocyte NMN (CBX, p=0.0002; DO, p=0.0003), reducing oocyte NAD⁺ (CBX, p<0.0001; DO, p<0.0001), and reducing d3-NAD⁺ synthesis (CBX, p=0.027; DO, p<0.0001). Altered adenine nucleotide turnover emerged as a potential contributor to impaired NAD⁺ metabolism (AMP: CBX, p=0.028; DO, p=0.004). Restoring NAD⁺ levels during in vitro maturation with NMN in intact COCs reduced ROS (age, p<0.0001; H₂O₂, p<0.0001), increased glutathione (age, p=0.001; ROS, p<0.0001), and improved mitochondrial membrane potential (age, p<0.0001; ROS, p=0.006) in aged and H₂O₂-exposed mouse oocytes, but did not reduce ROS in DOs, demonstrating that NAD⁺-dependent benefits rely on cumulus-cells.

Conclusion
These findings identify a new model of somatic–germline metabolic coupling for NAD⁺ biosynthesis, placing age-related deterioration in cumulus-cell-mediated metabolic support as a key driver of impaired oocyte NAD⁺ levels and redox dysregulation with ageing.