NERVE GROWTH-FACTOR (NGF) REGULATES TACHYKININ GENE-EXPRESSION AND BIOSYNTHESIS IN RAT SENSORY NEURONS DURING EARLY POSTNATAL-DEVELOPMENT

The regulatory effects of nerve growth factor (NGF) on tachykinin bios ynthesis in rat primary sensory neurons during the period of postnatal development were examined under in vivo and in vitro conditions. Admi nistration of NGF to neonatal rats led to a significant increase in pr otein levels of substance P (SP) and neurokinin A (NKA) in trigeminal and dorsal root ganglia (DRG). In addition, Northern blot analysis rev ealed that preprotachykinin mRNA was upregulated in sensory ganglia of neonatal animals after treatment with NGF. Using a well-defined in vi tro system for neonatal rat DRG and trigeminal ganglia neurons, we fou nd that addition of NGF induced SP and NKA protein levels in a dose-de pendent manner. Furthermore, preprotachykinin mRNA was markedly increa sed in cultured DRG and trigeminal ganglia neurons in the presence of NGF. Thus, our results clearly demonstrate that NGF regulates tachykin in gene expression and biosynthesis both in vivo and in vitro during t he developmental period of rat sensory neurons.