Stimulatory effects of substance P and nerve growth factor (NGF) on neurite outgrowth in embryonic chick dorsal root ganglia

Abstract

Synthetic Substance P at 10 4 M and Nerve Growth Factor (NGF) at 2 ng ml produced a 3-fold increase in the concentration of cyclic AMP 10 min after addition to cultured chick dorsal root ganglia. Subsequently, increased fiber outgrowth was observed 24 hrs after these additions. Dibutyryl cyclic AMP at 10 −3 M also produced a similar induction of fiber outgrowth. These studies suggest that Substance P and NGF might act by increasing cyclic AMP levels, which may then act as an initial “second messenger”, inducing the morphological differentiation at a later time.