REGULATED EXPRESSION OF THE NEURAL CELL-ADHESION MOLECULE L1 BY SPECIFIC PATTERNS OF NEURAL IMPULSES

Development of the mammalian nervous system is regulated by neural imp ulse activity, but the molecular mechanisms are not well understood. I f cell recognition molecules [for example, L1 and the neural cell adhe sion molecule (NCAM)] were influenced by specific patterns of impulse activity, cell-cell interactions controlling nervous system structure could be regulated by nervous system function at critical stages of de velopment. Low frequency electrical pulses delivered to mouse sensory neurons in culture (0.1 hertz for 5 days) down-regulated expression of L1 messenger RNA and protein (but not NCAM). Fasciculation of neurite s, adhesion of neuroblastoma cells, and the number of Schwann cells on neurites was reduced after 0.1-hertz stimulation, but higher frequenc ies or stimulation after synaptogenesis were without effect.