Hemoglobin-Improved Protection in Cultured Cerebral Cortical Astroglial Cells: Inhibition of Oxidative Stress and Caspase Activation

Abstract

Oxidative stress plays a major role in triggering astroglial cell death in diverse neuropathological conditions such as ischemia and neurodegenerative diseases. Numerous studies indicate that hemoglobin (Hb) is expressed in both resting and reactive glia cells, but nothing is known regarding a possible role of Hb on astroglial cell survival. Thus, the purpose of the present study was to investigate the potential glioprotective effect of Hb on hydrogen peroxide (H2O2)-induced oxidative stress and apoptosis in cultured rat astrocytes. Our study demonstrates that administration of graded concentrations of Hb (10−12 to 10−6 M) to H2O2-treated astrocytes reduces cell death in a concentration-dependent manner. H2O2 treatment induces the accumulation of reactive oxygen species (ROS) and nitric oxide (NO), a drop of the mitochondrial membrane potential, and a stimulation of caspase-3/7 activity. Exposure of H2O2-treated cells to Hb was accompanied by marked attenuations of ROS and NO surproductions, mitochondrial membrane potential reduction, and caspase-3/7 activity increase. The protective action of Hb was blocked by the protein kinase A (PKA) inhibitor H89, the protein kinase C (PKC) inhibitor chelerythrine, and the mitogen-activated protein (MAP)-kinase kinase (MEK) inhibitor U0126. Taken together, these data demonstrate for the first time that Hb is a glioprotective factor that protects astrocytes from apoptosis induced by oxidative stress and suggest that Hb may confer neuroprotection in neurodegenerative diseases. The anti-apoptotic activity of Hb on astrocytes is mediated through the PKA, PKC, and MAPK transduction pathways and can be accounted for by inhibition of oxidative stress-induced mitochondrial dysfunctions and caspase activation.

Cell-free oxidized hemoglobin drives reactive oxygen species production and pro-inflammation in an immature primary rat mixed glial cell culture

“…Interestingly, and somewhat contradictory, some studies have actually reported beneficial effects following exposure to cell-free Hb. For instance, Amri et al [ 14 ] report that oxyHb in low concentrations protects cortical astroglial cell cultures by inhibiting oxidative stress and caspase activation following exposure to hydrogen peroxide. The protective effect of oxyHb was linked to its ability to induce the protein kinase A and C signal transduction pathways whilst reducing nuclear factor kappa beta (NFΚB) activation [ 14 ].…”

“…For instance, Amri et al [ 14 ] report that oxyHb in low concentrations protects cortical astroglial cell cultures by inhibiting oxidative stress and caspase activation following exposure to hydrogen peroxide. The protective effect of oxyHb was linked to its ability to induce the protein kinase A and C signal transduction pathways whilst reducing nuclear factor kappa beta (NFΚB) activation [ 14 ]. An increased understanding and appreciation of the role of different Hb-metabolites, as well as triggered causal pathways, is vital in order to develop and implement neuroprotective strategies and deducing a possible therapeutic window for intervention with Hb-metabolite scavengers.…”

RNA‐Seq analysis of knocking out the neuroprotective proton‐sensitive GPR68 on basal and acute ischemia‐induced transcriptome changes and signaling in mouse brain

“…In multiple studies, an increase in neuronal hemoglobin or related proteins, including haptoglobin and neuroglobin, provides protection against oxidative stress or ischemia 33‐39 . Thus, our RNA‐Seq result suggests that a GPR68‐dependent upregulation of hemoglobin expression serves as one potential mechanism by which GPR68 leads to neuroprotection in ischemia.…”

Growth Hormone and Neuronal Hemoglobin in the Brain—Roles in Neuroprotection and Neurodegenerative Diseases

“…Interestingly, ischemic preconditioning to hypoxia in vitro robustly increases nHb expression in neuronal cultures from E-17 rats ( 101 ). A plausible explanation for this is that Hb inhibits oxidative stress-induced mitochondrial dysfunction and caspase activation via the protein kinase A, protein kinase C, and mitogen-activated protein (MAP)-kinase signal transduction pathways ( 102 ).…”