The mechanisms of male infertility as a function of age remain underappreciated. Oocytes and ovarian tissue, among other somatic tissues, have been found to have decreasing amounts of nicotinamide adenine dinucleotide (NAD+) with increasing age. However, research into whether or not NAD+ levels affect male reproduction is still in its infancy. This study looked into whether or not older fathers have lower levels of NAD+ in their sperm. Researchers also looked into a possible connection between sperm NAD+ levels and sperm quality. Participants in this pilot observational cohort study were 51 males  (< 30 years: 91.61 ± 15.59 nmol/106 sperm, 30–40 years: 125.60 ± 16.28 nmol/106 sperm, > 40 years: 115.59 ± 16.55 nmol/1066 sperm) who sought preconception advice at a university-affiliated reproductive medical clinic. Their semen was analyzed, and their anthropometric data was collected. The levels of NAD+ in their sperm were measured spectrophotometrically. Key indicators of sperm quality varied significantly across the 3 age groups. However, the sperm NAD + level was similar throughout the three age groups (30 years: 91.61 15.59 nmol/106 sperm, 30-40 years: 125.60 16.28 nmol/106 sperm, and>40 years: 115.59 16.55 nmol/106 sperm). The content of NAD+ in sperm did not differ significantly with age (r2 = 0.018, P=0.35), as determined by linear regression. There was a significant inverse relationship between sperm NAD + concentrations and sperm quality indices such as concentration (r2=0.78, P<0.0001), count (r2=0.47, P<0.0001), mobile sperm number (r2 = 33, P<0.0001), and DFI (r2= 0.35, P<0.0001). There was no correlation between sperm NAD + concentration and sperm volume or motility. The concentration of NAD+ in sperm does not change with age, in contrast to the concentration in oocytes and ovarian tissue. Sperm NAD+ levels are inversely associated with sperm quality, which points to a novel role of NAD+ in spermatogenesis that needs more research and could lead to new pharmaceutical therapies for oligozoospermia.

Source: bmcurol.biomedcentral.com/articles/10.1186/s12894-022-01107-3