CRF and urocortin differentially modulate GluR delta 2 expression and distribution in parallel fiber-Purkinje cell synapses

Corticotropin-releasing factor (CRF) and urocortin (UCN) are closely related multifunctional regulators, governing, among other processes, Purkinje cell development. Here, we investigate the effects of CRF and UCN on Purkinje cells in organotypic slices. We show that both peptides upregulate delta 2 ionotropic glutamate receptor gene expression, and increase the abundance of the receptor in the postsynaptic density. However, only UCN treatment results in increased delta 2 protein level per Purkinje cell, implying the existence of posttranscriptional regulation of GluR delta 2 mRNA. CRF, in contrast, reduces the number of delta 2-positive dendritic shafts per cell, implying that the increase of GluR delta 2 in remaining synapses may be mainly due to its retargeting. We further observed different patterns of GluR delta 2 distribution in the zone of postsynaptic density upon CRF and UCN treatment. CRIT treatment results in a clustered distribution of GluR delta 2 along the postsynaptic density, whereas UCN treatment provides a linear distribution. (c) 2005 Elsevier Inc. All rights reserved.