Objective The functional roles of protein kinase C （PKC） in the neurite outgrowth and nerve regeneration remain controversial. The present study was aimed to investigate the role of PKC in neurite outgrowth, by studying their regulatory effects on neurite elongation in spinal cord neurons in vitro. Methods The anterior-horn neurons of spinal cord from embryonic day 14 （E14） Sprague-Dawley （SD） rats were dissociated, purified and cultured in the serum-containing medium. The ratio of membrane-PKC （mPKC） activity to cytoplasm-PKC （cPKC） activity （m/c-PKC） was studied at different time points during culture. Results Between 3-11 d of culture, the change of m/c-PKC activity ratio and PKC-βⅡ expression in the neurite were both significantly correlated with neurite outgrowth （r=0.95, P 〈 0.01; r=0.73, P 〈 0.01, respectively）. Moreover, PMA, an activator of PKC, induced a dramatic elevation in the m/c-PKC activity ratio, accompanied with the increase in neurite length （r=-0.99, P 〈 0.01）. In contrast, GF 109203X, an inhibitor of PKC, significantly inhibited neurite elongation, which could not be reversed by PMA. Conclusion PKC activity may be important in regulating neurite outgrowth in spinal cord neurons, and βⅡ isoform of PKC probably plays a major role in this process.
