Developmental expression of ZnT3 in mouse brain: correlation between the vesicular zinc transporter protein and chelatable vesicular zinc (CVZ) cells. Glial and neuronal CVZ cells interact.

We examine the expression pattern of ZnT3 in the cerebral and cerebellar areas of mouse brain throughout development. During embryogenesis and early postnatal stages, ZnT3 transcripts were detected in several areas. Label was clear in areas related to proliferation and differentiation. As development proceeded, the label gradually disappeared in these areas and increased in the chelatable vesicular zinc (CVZ) system. To assess whether ZnT3 was expressed in all CVZ cells, its distribution pattern was studied through postnatal stages using a retrograde zinc transport method. While the ZnT3 expression pattern and the distribution of CVZ cells coincided from P12 to adulthood, this coincidence was not detected in early postnatal days. Moreover, immunohistochemical procedures highlighted a differential phenotype within CVZ cells throughout postnatal development. These findings suggest the presence of different CVZ cell subpopulations throughout brain development and, consequently, the existence of distinct chelatable vesicular zinc pools.