The temporal and spatial development of corticotropin-releasing factor (CRF) binding sites and CRF afferents in the...

The intent of this study is to determine the developmental timecourse of the appearance and distribution of corticotropin releasing factor (CRF) binding sites within the developing opossum cerebellum, and to correlate this with the temporal and spatial distribution of CRF-labeled axons. 125I-labeled ovine CRF was used to identify the distribution and temporal expression of CRF binding sites in the opossum cerebellum. By PD8, binding sites are evident over cells in the external granular layer, as well as the subjacent immature Purkinje cell layer, but not over the ventricular layer or the intermediate zone. At PD 8, the intermediate zone, located between the ventricular and immature Purkinje cell layers, contains migrating nuclear, Golgi and Purkinje cells. By PD12, binding sites are present over all layers of the immature cerebellum (the external granular layer, the multitiered Purkinje cell layer, and the intermediate zone of migrating cells), except the ventricular layer. The adult distribution of CRF binding sites is evident by PD30-38 which includes the molecular, Purkinje and internal granule cell layers. The present results provide the first account of the ontogeny of CRF binding sites in the developing cerebellum. The early expression and distribution of CRF receptors, when correlated with the temporal expression and distribution of the peptide, provide additional evidence to support our working hypothesis that CRF functions as a regulator of developmental events which is distinct from its proposed function as a neuromodulator in the mature cerebellum.