Localized expression of BMP and GDF mRNA in the rodent brain

Expression of BMP- and GDF-related factors within the transforming growth factor-beta (TGF-beta) superfamily was examined in the rat and mouse brain by in situ hybridization. Strong signals were obtained in neurons for GDF-1 and GDF-10. GDF-1 is expressed at postnatal day 6 in the cerebral cortex, hippocampal CA1 through CA3 neurons, while only weakly expressed by cells in the dentate gyrus. Granule cells and neurons in the polymorph layer of the dentate gyrus are GDF-1-positive, as are the majority of neurons in the cortex. GDF-10 shows a distinct pattern of expression: At P6, strong labelling was seen in the superficial layers of cortex, notably in the posterior cingulate cortex, and in CA3 and dentate gyrus. From postnatal day 21, GDF-1 expression is strong in the hippocampus, cortex, and thalamic nuclei, while GDF-10 expression becomes restricted to the granule cell layer in the dentate gyrus. In contrast, OP-1 expression is restricted throughout development to cells of the medial habenular nucleus, choroid plexus, and leptomeninges. The markedly different expression patterns of these BMPs suggest they serve separate functions in the brain.