IMMUNOSUPPRESSANT FK506 PREVENTS MOSSY FIBER SPROUTING INDUCED BY KINDLING STIMULATION

Kindling stimulation induces expansive growth of the axons of the dent ate granule cells; the messy fiber, into several areas of the hippocam pus. An intraperitoneal injection of the immunosuppressant drug FK506, which is a specific inhibitor of Ca2+-calmodulin dependent phosphatas e, calcineurin, prevented the full development of kindling as well as messy fiber sprouting. The results show a correlation between messy fi ber sprouting and the development of kindling. The results suggest als o that calcineurin may have a promoting role in messy fiber sprouting and subsequent synaptogenesis.