Regulation of dendritic spine stability

Dendritic spines undergo several types of transformations, ranging from gro wth to collapse, and from elongation to shortening, and they experience dyn amic morphological activity on a rapid time scale. Changes in spine number and morphology occur under pathological conditions like excitotoxicity, but also during normal central nervous system development, during hormonal flu ctuations, and in response to neural activity under physiological circumsta nces. We briefly review evidence for various types of alterations in spines , and discuss the possible molecular,basis for changes in spine stability. Filamentous actin appears to be the most important cytoskeletal component o f spines, and a growing list of actin-associated and actin-regulatory prote ins has been reported to reside within spines. We conclude that spines cont ain two distinct pools of actin filaments tone stable, the other unstable) that provide the spine with both a stable core structure and a dynamic, com plex shape. Finally, we review the current state of knowledge of actin fila ment regulation, based:on:studies in nonneuronal cells. Hippocampus 2000;10 :542-554. (C) 2000 Wiley-Liss, Inc.