Somatostatin enhances nerve growth factor-induced neurite outgrowth in PC12 cells

The neuropeptide somatostatin has been found to be abundant in numerous developing regions within the central nervous system. In order to understand the role of somatostatin in development, effects of exposure to the neuropeptide were studied in PC12 cells, a well characterized model of neuronal differentiation. Somatostatin increased neurite outgrowth after 2 days in culture and enhanced neurite outgrowth after nerve growth factor (NGF) exposure. This effect was inhibited by somatostatin antibody and pertussis toxin. Somatostatin had no effect on NGF binding or internalization but did cause a decrease in cAMP levels during the time of maximal stimulation of neurite outgrowth. In a protein kinase A-deficient cell line (A126-1B2), somatostatin had no effect on neurite outgrowth. These results indicate that somatostatin may function as a differentiation factor in developing systems through inhibition of cAMP synthesis.