DEVELOPMENTAL ALTERATION AND NEURON-SPECIFIC EXPRESSION OF BONE MORPHOGENETIC PROTEIN-6 (BMP-6) MESSENGER-RNA IN RODENT BRAIN

Bone morphogenetic proteins (BMPs) are a group of proteins which induc e bone formation from mesenchymal cells. The existence of BMPs in the nervous system as well as in bone tissue has recently been reported. I n this study, we show that BMP-B is neuron-specific, and describe the temporal and spatial expression patterns of BMP-6 mRNA in the developi ng rat and gerbil brain. Northern blot analysis showed that the BMP-6 transcript level was specifically high from newborn to 3 weeks after b irth compared with those in fetal and adult rats. In situ hybridizatio n showed that most of the neurons possessed high levels of BMP-6 mRNA in the neonatal brain, while in the adult brain, BMP-6 mRNA level was significantly decreased in most of the neurons except those in hippoca mpus which retained high levels. Furthermore, to show that the BMP-6 e xpression was specific to neurons, we induced delayed neuronal cell de ath and compensative glial cell proliferation in the gerbil hippocampu s by transient ischemia. Our findings collectively suggest that BMP-6 is neuron-specific and may play important roles in neuronal maturation and synapse formation.