Somatostatin enhances neurite outgrowth in PC12 cells

The rat pheschromocytoma cell line PC12 forms neurites in response to nerve growth factor (NGF), and it was also reported to extend processes in the p resence of somatostatin (somatotropin release-inhibiting factor, SRIF), a n euroactive peptide that seems to act as a morphogenetic factor in the devel oping nervous system. In the present study, we re-evaluated the effects of SRIF on PC12 cell differentiation. Our results indicate that SRIF alone is ineffective in promoting neurite outgrowth. Instead, SRIF or its analogue, octreotide (a SRIF agonist on the receptor subtypes 2, 3 and 5), potentiate s neurite extension induced by NGF. These results suggest that SRIF enhance s neurite formation in PC12 cells without directly promoting neurite outgro wth. SRIF potentiation of NGF-induced neurite outgrowth persists at least i n parr in the presence of pertussis toxin (PTX), suggesting the involvement of PTX-insensitive G-proteins. In addition, protein kinase-dependent pathw ays are likely to mediate SRIF effects on NGF-induced differentiation. (C) 1998 Elsevier Science B.V. All rights reserved.