title: Urocortin, but not urocortin II, protects cultured hippocampal neurons from oxidative and excitotoxic cell death via corticotropin-releasing hormone receptor type I.
abstract: Urocortin and urocortin II are members of the corticotropin-releasing hormone (CRH) family of neuropeptides that function to regulate stress responses. Two high-affinity G-protein-coupled receptors have been identified that bind CRH and/or urocortin I and II, designated CRHR1 and CRHR2, both of which are present in hippocampal regions of mammalian brain. The hippocampus plays an important role in regulating stress responses and is a brain region in which neurons are vulnerable during disease and stress conditions, including cerebral ischemia, Alzheimer's disease, and anxiety disorders. Here we report that urocortin exerts a potent protective action in cultured rat hippocampal neurons with concentrations in the range of 0.5-5.0 pm, increasing the resistance of the cells to oxidative (amyloid beta-peptide, 4-hydroxynonenal, ferrous sulfate) and excitotoxic (glutamate) insults. We observed that urocortin is 10-fold more potent than CRH in protecting hippocampal neurons from insult, whereas urocortin II is ineffective. RT-PCR and sequencing analyses revealed the presence of both CRHR1 and CRHR2 in the hippocampal cultures, with CRHR1 being expressed at much higher levels than CRHR2. Using subtype-selective CRH receptor antagonists, we provide evidence that the neuroprotective effect of exogenously added urocortin is mediated by CRHR1. Furthermore, we provide evidence that the signaling pathway that mediates the neuroprotective effect of urocortin involves cAMP-dependent protein kinase, protein kinase C, and mitogen-activated protein kinase. This is the first demonstration of a biological activity of urocortin in hippocampal neurons, suggesting a role for the peptide in adaptive responses of hippocampal neurons to potentially lethal oxidative and excitotoxic insults.
authors.affiliation: Laboratory of Neurosciences, Gerontology Research Center, National Institute on Aging, Baltimore, Maryland 21224, USA.
authors.forename: Ward A
authors.initials: WA
authors.lastname: Pedersen
authors.forename: Ruiqian
authors.initials: R
authors.lastname: Wan
authors.forename: Peisu
authors.initials: P
authors.lastname: Zhang
authors.forename: Mark P
authors.initials: MP
authors.lastname: Mattson
mesh_terms: D000447:Aldehydes / Q000633:toxicity; D016229:Amyloid beta-Peptides / Q000633:toxicity; D000818:Animals; D002478:Cells, Cultured; D003346:Corticotropin-Releasing Hormone / Q000494:pharmacology*; D017868:Cyclic AMP-Dependent Protein Kinases / Q000378:metabolism; D019610:Cytoprotection / Q000502:physiology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005296:Ferrous Compounds / Q000633:toxicity; D018698:Glutamic Acid / Q000633:toxicity; D006624:Hippocampus / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D015227:Lipid Peroxidation / Q000187:drug effects; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D009474:Neurons / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D018696:Neuroprotective Agents / Q000494:pharmacology; D018384:Oxidative Stress / Q000187:drug effects* / Q000502:physiology; D011493:Protein Kinase C / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D018019:Receptors, Corticotropin-Releasing Hormone / Q000378:metabolism*; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology; D054832:Urocortins; D000099052:CRF Receptor, Type 1
chemical_list: D000447:Aldehydes; D016229:Amyloid beta-Peptides; D004791:Enzyme Inhibitors; D005296:Ferrous Compounds; D018696:Neuroprotective Agents; D018019:Receptors, Corticotropin-Releasing Hormone; D054832:Urocortins; C020748:ferrous sulfate; D018698:Glutamic Acid; D000099052:CRF Receptor, Type 1; D003346:Corticotropin-Releasing Hormone; D017868:Cyclic AMP-Dependent Protein Kinases; D011493:Protein Kinase C; D020928:Mitogen-Activated Protein Kinases; C027576:4-hydroxy-2-nonenal