Pyroglutamyl [correction of Pyroglutamil] -peptidase I activity in the cortex of the cat brain during development

Thyrotropin Releasing Hormone (TRH) is a principal regulator of thyroid system function. However, significant concentrations of TRH were found throughout the central nervous system, the cortex being one of the areas most richly endowed with thyroliberin. Research concerning the functional role of this brain peptide is performed, in part, by studying peptidase enzymes which may be involved in the inactivation of the peptide. The pGlu-His bond is cleaved by two pyroGlu-peptidases: I (soluble) and II (membrane-bound). In the present investigation, developmental activity of the soluble form is described in the cortices of the cat brain. The selected maturation stages were 15 and 30 days postnatal. The cortices were the frontal, parietal, area 17 and areas 18 and 19 as a whole, distinguishing brain hemispheres in all cases. PyroGlu-aminopeptidase I activity increased significantly with age in all the brain regions except area 17. It is suggested that this enzyme activity plays a part in the neurochemical changes that take place during brain maturation.