Immunohistochemical evidence for the implication of PC1 in the processing of proneurotensin in rat brain

Biochemical studies have shown that prohormone convertases PC1, PC2 and PC5 A all have the capacity to process, with different specificities, the neuro tensin/neuromedin N precursor, pro-NT/NN. A previous study from our laborat ory has demonstrated that in rat brain, both PC2 and PC5A may be co-express ed with NT, lending support to a physiological implication of these Mo enzy mes in the endoproteolytic maturation of pro-NT/NN. In the present study, w e sought to determine whether PC1 might also be involved in this process by comparing the immunohistochemical distribution of the enzyme with that of NT in both singly labeled and dually labeled serial brain sections. PC1 was found to co-localize extensively with NT throughout the rat neuraxis. Howe ver, there were important regional variations in the proportion of NT neuro ns co-expressing PC1. Furthermore, this proportion was negatively correlate d with that of NT neurons expressing PC5, suggesting that PC1 may serve as an alternative to PC5A for processing pro-NT/NN in mammalian brain. NeuroRe port 11:3443-3447 (C) 2000 Lippincott Williams & Wilkins.