Human serum pyroglutamyl-beta-naphthylamide hydrolyzing activity during development and aging

Pyroglutamyl-beta-naphthylamide hydrolyzing activity (pGluHA) is reported to be capable of removing the amino-terminal pyroglutamic acid residue from peptides (e.g. TRH or GnRH) and artificial substrates. However, its functional role in serum is not yet understood. The aim of the present study was to analyze the activity of pGluHA in human serum during development and aging, in an apparently healthy population of 139 men and 148 women. To measure pGluHA we used pGlu-beta-naphthylamide as the substrate. Sex differences and age-related changes were observed in men and women. In addition, the developmental profile was notably different between men and women. In men, activity increased steadily until full sexual maturity, but did not change substantially after puberty. In women, activity increased significantly in advanced ages but there were no significant changes in the rest of the age groups tested. Significant sex differences were observed in subjects 46-65 years old, the activity being higher in men than women. In the total population, a significant direct correlation was observed between pGluHA and age. Considered independently, men and women also showed a highly significant direct correlation between pGluHA and age. These results may reflect changes in the functional status of its circulating substrates during development and aging.