MORPHOLOGICAL CHANGES AND F-ACTIN DYNAMICS IN THE CEREBELLAR PINCEAU IN ACUTE RAT BRAIN SLICES.

BOBIK, M. ; CAPANI, F. ; LEV-RAM, V. ; ELLISMAN, M. H. ; MARTONE, M. E.

San Diego

Congreso; Society for Neuroscience Meeting; 2001

The pinceau is a structure formed by descending basket cell axonal collaterals converging on the Purkinje cell initial segment. We have previously shown that the basket cell terminals and astrocytic processes in the pinceau have a selectively high concentration of F-actin compared to other brain structures (Capani, J Compar Neurol, 2001). In order to further investigate the mechanics of this area in situ, we examined the morphology of pinceau fibers in acute cerebellar slices. Previous studies in hippocampal slices have shown that considerable structural plasticity occurs within the first hour after slice sectioning (Kirov, J Neurosci, 19, 2876; 1999). In this study, we examined both the ultrastructural morphology and F-actin staining in pinceau fibers immediately after slicing. The interval between decapitation, sectioning of slices in oxygenated Ringer solution, and fixation of cut slices was 5-6 minutes. We observed selective loss of F-actin labeling in the pinceau during this interval as compared to perfused mice. Staining in the molecular layer and the glomeruli was unchanged. Analysis of experiments using electron microscopy revealed changes in basket cell morphology and astrocytic swelling . Taken together with previous studies of pinceau-associated proteins and structural elements, the present results suggest potential structural reorganization within this region. We are now analyzing whether changes in F-actin staining in slices can be correlated with increased synapse formation and/or astrocyte swelling.