S-100-IMMUNOREACTIVITY IN SPONTANEOUSLY ACTIVE SNAIL NEURONS

The distribution of S-100-immunoreactive material was examined in the central nervous system of the gastropod snail, Helix pomatia, and elec trophysiological properties of S-100-positive neurons were characteriz ed. Immunocytochemical studies revealed S-100-like protein to be prese nt in neurons localized in the cerebral, left parietal, and visceral g anglia, but not in glial cells. Among the immunoreactive neurons we id entified the giant cells LPa3 and LPa4. Western blots showed a single S-100-immunoreactive band at 12-14 kDa. S-100-positive neurons are dis tinguished by spontaneous discharge activity in a beating or bursting mode and a prominent Ca2+-activated potassium outward current. Our res ult show that a S-100-like protein exclusively present in neurons of t he Helix central nervous system is correlated with spontaneous dischar ge activity of these cells.