BASIC FIBROBLAST GROWTH-FACTOR AND BRAIN-DERIVED NEUROTROPHIC FACTOR PROMOTE SURVIVAL AND NEURONAL CIRCUIT FORMATION IN ORGANOTYPIC HIPPOCAMPAL CULTURE

Neurotrophic effects in vitro have been generally related to promotion of differentiation, maturation and survival, but little is known abou t the effect on neuronal circuit formation. The organotypic culture sy stem would be an available technique to investigate neuronal circuit f ormation and neuronal cell-cell interactions. As we reported previousl y, an optical recording system is a useful technique to comprehend neu ronal activities and circuit from multi-points simultaneously. In this study, we investigated whether continuous application of basic fibrob last growth factor (bFGF or FGF-2) and brain-derived neurotrophic fact or (BDNF) inhibited neuronal cell death induced by serum-deprivation i n organotypic culture using propidium iodide staining, and we analyzed effects of bFGF and BDNF on the formation of neuronal circuits using the optical recording system. Continuous application of bFGF or BDNF s ignificantly protected the slices from neuronal death. Optical recordi ng also demonstrated that addition of 10 ng/ml bFGF or 50 ng/ml BDNF e nhanced optical signals in all hippocampal areas significantly. These data strongly suggest that bFGF and BDNF promote the formation of neur onal circuits as well as survival and that optical recording of organo typic hippocampal slices would be a useful technique that enables us t o analyze neuronal circuit formation easily.