Surge of Peripheral Arginine Vasopressin in a Rat Model of Birth Asphyxia

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Summanen , M , Back , S , Voipio , J & Kaila , K 2018 , ' Surge of Peripheral Arginine Vasopressin in a Rat Model of Birth Asphyxia ' , Frontiers in Cellular Neuroscience , vol. 12 , 2 . https://doi.org/10.3389/fncel.2018.00002

Title: Surge of Peripheral Arginine Vasopressin in a Rat Model of Birth Asphyxia
Author: Summanen, Milla; Back, Susanne; Voipio, Juha; Kaila, Kai
Contributor organization: Biosciences
Laboratory of Neurobiology
Juha Voipio / Principal Investigator
Physiology and Neuroscience (-2020)
Kai Kaila / Principal Investigator
Neuroscience Center
Date: 2018-01-19
Language: eng
Number of pages: 9
Belongs to series: Frontiers in Cellular Neuroscience
ISSN: 1662-5102
DOI: https://doi.org/10.3389/fncel.2018.00002
URI: http://hdl.handle.net/10138/233470
Abstract: Mammalian birth is accompanied by a period of obligatory asphyxia, which consists of hypoxia (drop in blood O-2 levels) and hypercapnia (elevation of blood CO2 levels). Prolonged, complicated birth can extend the asphyxic period, leading to a pathophysiological situation, and in humans, to the diagnosis of clinical birth asphyxia, the main cause of hypoxic-ischemic encephalopathy (HIE). The neuroendocrine component of birth asphyxia, in particular the increase in circulating levels of arginine vasopressin (AVP), has been extensively studied in humans. Here we show for the first time that normal rat birth is also accompanied by an AVP surge, and that the fetal AVP surge is further enhanced in a model of birth asphyxia, based on exposing 6-day old rat pups to a gas mixture containing 4% O-2 and 20% CO2 for 45 min. Instead of AVP, which is highly unstable with a short plasma half-life, we measured the levels of copeptin, the C-terminal part of prepro-AVP that is biochemically much more stable. In our animal model, the bulk of AVP/copeptin release occurred at the beginning of asphyxia (mean 7.8 nM after 15 min of asphyxia), but some release was still ongoing even 90 min after the end of the 45 min experimental asphyxia (mean 1.2 nM). Notably, the highest copeptin levels were measured after hypoxia alone (mean 14.1 nM at 45 min), whereas copeptin levels were low during hypercapnia alone (mean 2.7 nM at 45 min), indicating that the hypoxia component of asphyxia is responsible for the increase in AVP/copeptin release. Alternating the O-2 level between 5 and 9% (CO2 at 20%) with 5 min intervals to mimic intermittent asphyxia during prolonged labor resulted in a slower but quantitatively similar rise in copeptin (peak of 8.3 nM at 30 min). Finally, we demonstrate that our rat model satisfies the standard acid-base criteria for birth asphyxia diagnosis, namely a drop in blood pH below 7.0 and the formation of a negative base excess exceeding -11.2 mmol/l. The mechanistic insights from our work validate the use of the present rodent model in preclinical work on birth asphyxia.
Subject: arginine vasopressin (AVP)
copeptin
birth asphyxia
hypothalamic-pituitary axis (HPA axis)
blood gases
base deficit
perinatal
neonatal
PARAVENTRICULAR NUCLEUS
COPEPTIN
BRAIN
HYPOXIA
STRESS
ENCEPHALOPATHY
HYPOTHALAMUS
PRECURSOR
RELEASE
NEURONS
3112 Neurosciences
3124 Neurology and psychiatry
Peer reviewed: Yes
Rights: cc_by
Usage restriction: openAccess
Self-archived version: publishedVersion


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