Alterations with age of the neurons expressing P(0) in the rat spinal cord.

In mammals, P(0) expression is thought to be restricted to the peripheral nervous system (PNS), whereas in some other vertebrates it is expressed not only in the PNS but also in the central nervous system (CNS). Previously we reported that P(0) is expressed in the rat spinal cord and that its glycosylation state changes with age. In this report, we determine, by immunohistochemical and immunocytochemical analyses, that the neurons in the spinal cord express P(0). Furthermore, our data show that the number of neurons expressing P(0) decreases and their sizes become smaller with age. Thus, the results emphasize the importance of neurons expressing P(0) in the spinal cord in the formation and maintenance of the neural network.