Erythropoietin (EPO) plays an important role in the brain's response to neuronal injury. Systemic administration of recombinant human EPO (rhEPO) protects neurons from injury after middle cerebral artery occlusion, traumatic brain injury, neuroinflammation, and excitotoxicity. Protection is in part mediated by antiapoptotic mechanisms. We conducted parallel studies of rhEPO in a model of transient global retinal ischemia induced by raising intraocular pressure, which is a clinically relevant model for retinal diseases. We observed abundant expression of EPO receptor (EPO-R) throughout the ischemic retina. Neutralization of endogenous EPO with soluble EPO-R exacerbated ischemic injury, which supports a crucial role for an endogenous EPO͞EPO-R system in the survival and recovery of neurons after an ischemic insult. Systemic administration of rhEPO before or immediately after retinal ischemia not only reduced histopathological damage but also promoted functional recovery as assessed by electroretinography. Exogenous EPO also significantly diminished terminal deoxynucleotidyltransferase-mediated dUTP end labeling labeling of neurons in the ischemic retina, implying an antiapoptotic mechanism of action. These results further establish EPO as a neuroprotective agent in acute neuronal ischemic injury. E rythropoietin (EPO) has been viewed traditionally as a hematopoietic cytokine produced by the fetal liver and adult kidney in response to hypoxia. Results of recent studies now support a physiological role for EPO within the central nervous system. The expression of EPO and EPO receptors (EPO-Rs) in the central nervous system and the up-regulation of EPO by hypoxia͞ischemia in vitro and in vivo suggest that this cytokine is an important mediator of the brain's response to injury. Consistent with this hypothesis, pretreatment with exogenous EPO protects cultured neurons from hypoxia (1, 2), glutamate excitotoxicity (3), and growth-factor withdrawal (2). When administered systemically, EPO can cross the blood-brain barrier and reduce neuronal injury in animal models of focal ischemic stroke, traumatic brain injury, inflammation, kainate toxicity, and spinal cord injury (2, 4, 5). EPO rescues neurons from acute injury at least in part by inhibiting apoptosis via activation of specific protein kinase pathways (2) and the recruitment of NF-B (6).Prior studies of EPO in different models of brain injury raise the possibility that this cytokine may participate in the recovery of retinal neurons from ischemia. Retinal ischemia is a serious and common clinical problem. It occurs as a result of acute vascular occlusion and leads to visual loss in a number of ocular diseases such as acute glaucoma (7), diabetic retinopathy (8), and hypertensive vascular disease (9). Transient global retinal ischemia, for example, shares many similarities with transient global cerebral ischemia. Both cause selective damage of specific subpopulations of neurons. Pyramidal neurons in the CA-1 zone of the hippocampus are selectively vulnerable to trans...

Necroptosis is an important mode of neuronal cell death and involves autophagy in a model of retinal ischemia.

Cockayne syndrome and xeroderma pigmentosum-Cockayne syndrome complex are rare autosomal recessive disorders with poorly understood biology. They are characterized by profound postnatal brain and somatic growth failure and by degeneration of multiple tissues resulting in cachexia, dementia, and premature aging. They result in premature death, usually in childhood, exceptionally in adults. This study compares the clinical course and pathology of a man with Cockayne syndrome group A who died at age 31½ years with 15 adequately documented other adults with Cockayne syndrome and 5 with xeroderma pigmentosum-Cockayne syndrome complex. Slowing of head and somatic growth was apparent before age 2 years, mental retardation and slowly progressive spasticity at 4 years, ataxia and hearing loss at 9 years, visual impairment at 14 years, typical Cockayne facies at 17 years, and cachexia and dementia in his twenties, with a retained outgoing personality. He experienced several transient right and left hemipareses and two episodes of status epilepticus following falls. Neuropathology disclosed profound microencephaly, bilateral old subdural hematomas, white-matter atrophy, tigroid leukodystrophy with string vessels, oligodendrocyte proliferation, bizarre reactive astrocytes, multifocal dystrophic calcification that was most marked in the basal ganglia, advanced atherosclerosis, mixed demyelinating and axonal neuropathy, and neurogenic muscular atrophy. Cellular degeneration of the organ of Corti, spiral and vestibular ganglia, and all chambers of the eye was severe. Rarely, and for unexplained reasons, in some patients with Cockayne syndrome the course is slower than usual, resulting in survival into adulthood. The profound dwarfing, failure of brain growth, cachexia, selectivity of tissue degeneration, and poor correlation between genotypes and phenotypes are not understood. Deficient repair of DNA can increase vulnerability to oxidative stress and play a role in the premature aging, but why patients with mutations in xeroderma pigmentosum genes present with the Cockayne syndrome phenotype is still not known.