Ontogeny of soluble and particulate prolyl endopeptidase activity in several areas of the rat brain and in the pituitary gland

We have analyzed the activity of prolyl endopeptidase (PEP) in several areas of the rat brain (brain cortex, striatum, brain stem, cerebellum and hypothalamus) and in the pituitary gland during ontogeny. In all of these areas, we observed a reduction in PEP activity during development. However, the temporal profile of these alterations was found to be area specific and differences in the ontogeny of the soluble and particulate forms of PEP were observed. Thus, by postnatal day 20 (PD20), soluble PEP activity had began to decrease in the brain cortex and striatum, whereas decreased soluble PEP activity was observed earlier, at PD15, in the brain stem and cerebellum. Changes in the particulate fraction were even more pronounced. Senescence was associated with decreased soluble PEP activity in the striatum, but in contrast, particulate PEP activity was found to be increased in the senescent brain stem. The present results indicate that alterations in the levels of activity of PEP may represent an important event in the development and aging of the central nervous system.