Post-hypoxic and ischemic neuroprotection of BMP-7 in the cerebral cortex and caudate–putamen tissue of rat

Abstract

Previous reports have indicated that exogenous bone morphogenetic protein-7 (BMP-7) has a neuroprotective effect after cerebral ischemia injury and promotes motor function recovery, but the appropriate BMP-7 concentration and time course are unclear. Here, we assessed endogenous BMP-7 expression in hypoxia and ischemia-damaged brain tissues and investigated the effects of different BMP-7 concentrations in pre- and post-hypoxic primary rat neurons. The results showed that BMP-7 expression was significantly higher in the ischemic hemisphere. The expressions of BMP-7 and caspase-3 were localized in the cytoplasm of the primary cerebral cortical and caudate–putamen neurons 24h after hypoxia/reoxygenation. After BMP-7 treatment, the number of caspase-3 positive neurons began to decrease with increasing BMP-7 concentrations up to 80ng/ml, but not beyond. Although the numbers of caspase-3-positive neurons between pre- and post-hypoxia/reoxygenation were not significantly different, more dendrites were observed in the groups treated prior to hypoxia/reoxygenation. These results suggest that increased BMP-7 expression can be induced in the cerebral cortex and caudate–putamen both in vivo and in vitro in hypoxic-ischemic states. The neuroprotective mechanism of BMP-7 may include apoptosis suppression, and its effect was enhanced from 40 to 80ng/ml. Pre-hypoxic BMP-7 treatment may be useful to stimulate dendrite sprouting in non-injured neurons.