Neuroprotective Effects of Bone Morphogenetic Proteins (BMPs) in Primary Cortical Culture

• Main Authors: Su-Yu,Chen, 陳素瑜
• Other Authors: Jia-Yi,Wang
• Format: Others
• Language: zh-TW
• Published: 2001
• Online Access: http://ndltd.ncl.edu.tw/handle/73456204689743924513

碩士 === 國防醫學院 === 生理學研究所 === 89 === Bone morphogenetic proteins (BMPs) are members of TGF - b (transforming growth factor-b) superfamily. BMPs play an important role in gastrulation and neurulation during embryonic period. BMPs regulate growth, differentiation and apoptosis of neurons, and are important for neuron morphogenesis. BMPs have neurotrophin activities and it has been recently reported that pretreatment with BMP-6 or BMP-7 reduced ischemia-induced neuronal damages in rat brain in vivo. In this study, we further examined whether BMP-6 or BMP-7 have neuroprotective effects against neuronal death induced by two different injury paradigms such as hydrogen peroxide (H2O2) or hypoxia — reoxygenation (H/R) in vitro. The possible intracellular signaling pathways underlying the neuroprotective effects off BMP7 were also examined. Primary cultures were prepared from cerebral cortex of rat embryos (E16-17) and were subjected to H2O2 or H/R. We found that H2O2 caused concentration-dependent cell death as evidenced by morphological changes and increased lactate dehydrogenase (LDH) activities in the culture media. The density of neuronal cells, as identified by immunocytochemical staining against microtubule associated protein 2(MAP-2) or neuronal specific nuclear protein (NeuN), was also significantly decreased. Pretreatment with BMP-7, at 1.25 nM and 12.5 nM, significantly attenuated. H2O2- and H/R-induced toxicities. In defining the possible signalling pathways of BMPs’ neuroprotective effects, we observed that such protective effects could be attenuated by noggin, suggesting that the protective response was mediated through BMP receptors. The protective effects were enhanced by okadaic acid, a phosphatase inhibitor, suggesting involvement of phosphorylation. Consistent with the notion that mitogen-activated protein kinase pathways (MAPK pathways) is involved in TGF-β —induced response, we also observed that BMP7 -induced neuroprotection against H2O2 was antagonized by pretreatment with PD98059, a p42, 44 MAPK inhibitor, but not SB202191 or SB203580, p38 MAPK inhibitors, at 10 μM. The exclusion of the involvement of the phosphatidylinositol 3- kinase (IP3K) pathway was suggested by the fact that wortmannin did not inhibit BMPs’ protective effects. On the other hand, PKC (protein kinase C) appeared to be involved as both H7 and chelerythrine chloride attenuated BMPs’ protective effects. To further compare the neuroprotective effects of BMP with a well-known trophic factor glia derived neurotrophic growth factor (GDNF), we found that GDNF (1 nM) could also protect cultured cells from both H2O2 and H/R-induced toxicities. When cultures were transfected by herpes simplex virus (HSV) carrying the cDNA for GDNF (HSV-GDNF), GDNF levels in the culture media significantly increased and less degree of cell death caused by H2O2 were found, indicating the effectiveness of transfection. Similarly, when cultures were transfected by HSV carrying the cDNA for BMP-7, protective effects against H2O2 injury was noted. In sum, our data indicate that BMPs have neuroprotective effects against oxidative and hypoxia-reperfusion injury. The neuroprotective effect of BMP7 appeared to be mediated through BMP receptor, p42/44 MAPK, and PKC, but not p38 and IP3K pathways.