ABSTRACT
OBJECT: Granulocyte-macrophage colony-stimulating factor (GM-CSF) is a potent hematopoietic growth factor that both enhances the survival and drives the differentiation and proliferation of myeloid lineage cells. Recent studies have suggested that GM-CSF has a neuroprotective effect against CNS injury. In this paper, the authors investigated the neuroprotective effect of GM-CSF on neuron survival and locomotor behavior in a rat model of focal cerebral ischemic injury. MATERIALS: To understand its neuroprotective effect in vitro, GM-CSF was administered to a glutamate-induced excitotoxicity neuronal injury cell culture model that mimics the pathophysiology of focal hypoxic cerebral injury. In the animal study, the authors prepared a rat focal cerebral ischemia model by occluding the unilateral middle cerebral artery. They then examined the effects of GM-CSF administration on changes in infarct volume, apoptosis-related gene expression, and improvement in locomotor behavior. RESULTS: Treatment with GM-CSF significantly increased cell viability in a cell culture model of glutamate-induced neuronal injury. Furthermore, in vivo administration of GM-CSF at 60 microg/kg body weight daily for 5 consecutive days beginning immediately after injury decreased infarction volume, altered the expression of several apoptosis-related genes (Bcl-2, Bax, caspase 3, and p53), and improved locomotor behavior in the focal cerebral ischemia model. CONCLUSIONS: The GM-CSF had neuroprotective effects in in vitro and in vivo experiments and resulted in decreased infarction volume and improved locomotor behavior. Although the specific mechanism involved in stroke recovery was not fully elucidated as it was not the primary focus of this study, administration of GM-CSF appeared to decrease the extent of neuronal apoptosis by modulating the expression of several apoptosis-related genes such as Bcl-2, Bax, caspase 3, and p53. Further investigations are necessary to better understand the role of GM-CSF on neural regeneration during the recovery phase of a stroke, as well as the intracellular signal transduction pathways that mediate neuroprotection.
Subject(s)
Apoptosis/drug effects , Granulocyte-Macrophage Colony-Stimulating Factor/pharmacology , Ischemic Attack, Transient/drug therapy , Ischemic Attack, Transient/pathology , Neuroprotective Agents/pharmacology , Animals , Cell Line, Tumor , Cerebral Infarction/drug therapy , Cerebral Infarction/metabolism , Cerebral Infarction/pathology , Disease Models, Animal , Gene Expression/drug effects , Glutamic Acid/metabolism , Humans , Ischemic Attack, Transient/metabolism , Leukocytes, Mononuclear/drug effects , Male , Mesenchymal Stem Cells/drug effects , Motor Activity/drug effects , Neuroblastoma , Neurotoxins/metabolism , RNA, Messenger/metabolism , Rats , Rats, Sprague-Dawley , Receptors, Granulocyte-Macrophage Colony-Stimulating Factor/genetics , Receptors, Granulocyte-Macrophage Colony-Stimulating Factor/metabolism , Recovery of Function/drug effectsABSTRACT
Granulocyte-macrophage colony-stimulating factor (GM-CSF) is a hematopoietic cytokine that has the potential for clinical application. The biological effects of GM-CSF have been well characterized, and include stimulation of bone marrow hematopoietic stem cell proliferation and inhibition of apoptosis of hematopoietic cells. In contrast, the therapeutic effects of GM-CSF on the central nervous system in acute injury such as stroke and spinal cord injury have been reported only recently. To better understand the protective effect of GM-CSF on dopaminergic neurons in Parkinson's disease (PD), we investigated the effect of GM-CSF on the survival of dopamine neurons and changes in locomotor behavior in a murine PD model. We investigated the neuroprotective effects of GM-CSF in 1-methyl-4-phenylpyridinium (MPP+)-treated PC12 cells as well as in embryonic mouse primary mesencephalic neurons (PMNs) in vitro. To investigate the role of GM-CSF in vivo, we prepared a mouse 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) PD model, and examined the effects of GM-CSF on dopaminergic neuron survival in the substantia nigra and on locomotor behavior. Treatment with GM-CSF significantly reduced MPP+-induced dopaminergic cell death in PC12 cells and PMNs in vitro. GM-CSF modulated the expression of apoptosis-related proteins, Bcl-2 and Bax, in vitro. Furthermore, administration of GM-CSF (50 microg/kg body weight/day) in vivo for 7 days protected dopaminergic neurons in the substantia nigra and improved locomotor behavior in a mouse MPTP model of PD.
