title: Opposing effects of hypoxia on catecholaminergic locus coeruleus and hypocretin/orexin neurons in chick embryos.
abstract: Terrestrial vertebrate embryos face a risk of low oxygen availability (hypoxia) that is especially great during their transition to air-breathing. To better understand how fetal brains respond to hypoxia, we examined the effects of low oxygen availability on brain activity in late-stage chick embryos (day 18 out of a 21-day incubation period). Using cFos protein expression as a marker for neuronal activity, we focused on two specific, immunohistochemically identified cell groups known to play an important role in regulating adult brain states (sleep and waking): the noradrenergic neurons of the Locus Coeruleus (NA-LC), and the Hypocretin/Orexin (H/O) neurons of the hypothalamus. cFos expression was also examined in the Pallium (the avian analog of the cerebral cortex). In adult mammalian brains, cFos expression changes in a coordinated way in these areas. In chick embryos, oxygen deprivation simultaneously activated NA-LC while deactivating H/O-producing neurons; it also increased cFos expression in the Pallium. Activity in one pallial primary sensory area was significantly related to NA-LC activity. These data reveal that at least some of the same neural systems involved in brain-state control in adults may play a central role in orchestrating prenatal hypoxic responses, and that these circuits may show different patterns of coordination than seen in adults.
authors.affiliation: Department of Psychology, McGill University, Montreal, Quebec, Canada, H3A 1B1.
authors.forename: Jeremy P
authors.initials: JP
authors.lastname: Landry
authors.forename: Connor
authors.initials: C
authors.lastname: Hawkins
authors.forename: Sabrina
authors.initials: S
authors.lastname: Wiebe
authors.forename: Evan
authors.initials: E
authors.lastname: Balaban
authors.forename: Maria
authors.initials: M
authors.lastname: Pompeiano
mesh_terms: D000818:Animals; D030161:Avian Proteins / Q000378:metabolism*; D002395:Catecholamines / Q000378:metabolism*; D002642:Chick Embryo; D005260:Female; D005917:Globus Pallidus / Q000196:embryology / Q000503:physiopathology; D002534:Hypoxia, Brain / Q000503:physiopathology*; D007150:Immunohistochemistry; D047908:Intracellular Signaling Peptides and Proteins / Q000378:metabolism*; D008125:Locus Coeruleus / Q000196:embryology / Q000503:physiopathology*; D008297:Male; D009474:Neurons / Q000502:physiology*; D009479:Neuropeptides / Q000378:metabolism*; D000068797:Orexins; D016760:Proto-Oncogene Proteins c-fos / Q000378:metabolism
chemical_list: D030161:Avian Proteins; D002395:Catecholamines; D047908:Intracellular Signaling Peptides and Proteins; D009479:Neuropeptides; D000068797:Orexins; D016760:Proto-Oncogene Proteins c-fos
keywords: cFos; chick embryo; hypocretin/orexin; hypoxia; locus coeruleus