EXPRESSION OF PERIPHERIN, NADPH-DIAPHORASE AND NOS IN THE ADULT-RAT NEOCORTEX

PERIPHERIN is mainly expressed in peripheral neurones and in CNS neuro nes which extend axons into peripheral nerves. However, this intermedi ate filament protein has also been detected in a few other neurones en tirely located within the CNS. The present study focuses on the adult rat neocortex. Peripherin immunoreactive (P+) neuronal somata and thei r neuritic extensions were observed in cortical layers II, III, V and VI, while a few P+ nerve fibres could be seen in layer I. All the P+ n eurones could be selectively stained using reduced nicotinamide adenin e dinucleotide phosphate diaphorase (NADPH-d) histochemistry, a typica l feature of aspiny neurones. Some of the P+ neurones could also be im munostained with an antibody raised against nitric oxide synthase (NOS ). These results provide evidence that peripherin is present in a disc rete population of aspiny interneurones of the adult rat neocortex. Th e functional significance of the co-expression of peripherin and NOS n eeds further investigation.