VASOACTIVE-INTESTINAL-PEPTIDE BUT NOT GALANIN PROMOTES SURVIVAL OF NEONATAL RAT SYMPATHETIC NEURONS AND NEURITE OUTGROWTH OF PC12 CELLS

The synthesis of the neuropeptide galanin (GAL) is greatly enhanced af ter axonal lesion in different neuron populations of the peripheral an d central nervous system. In sympathetic ganglia, GAL-immunoreactive n erve fiber baskets have been found surrounding postganglionic neurons after axotomy. Until now, it is unclear if GAL may be involved in neur onal survival or regeneration as suggested for vasoactive intestinal p eptide (VIP) that is also upregulated after nerve lesion. We have, the refore, studied the effects Df GAL on survival of sympathetic neurons dissociated from newborn rat superior cervical ganglia and on neurite outgrowth of PC12 cells. These effects were compared to those elicited by VIP. Whereas VIP promoted survival of about 10% of sympathetic neu rons 2 days after nerve growth factor deprivation and induced neurite outgrowth of PC12 cells already at 6 h after addition of the peptide, GAL had no effect in either of these culture systems. While the induct ion of VIP may be beneficial for axotomized neurons, the functional si gnificance of increased GAL levels remains to be established.