Activity-dependent changes in spine formation due to CRF and urocortin in cerebellar Purkinje cells

Corticotropin-releasing factor (CRF) and urocortin (UCN) are potent regulators of Purkinje cell dendritic development including spines and synapses. Here, we demonstrate that CRF and UCN increase dendritic spine density in cerebellar Purkinje cells. Specific spine types in Purkinje cells are selectively affected: CRF promotes the mushroom type of spines, whereas at the same time UCN the thin type. Also, CRF and UCN are involved in the regulation of activity-dependent refinement of synaptic connections of Purkinje cells. Both peptides lead to increasing the length of the active zone and the postsynaptic density (PSD) in synapses between Purkinje cells and parallel fiber terminals. Finally, CRF and UCN are involved in processing the topological matching of presynaptic and postsynaptic specializations of synapses. Slices treated with CRF and UCN show less mismatched synapses in contrast to control slices.