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The Alteration of Neonatal Raphe Neurons by Prenatal-Perinatal Nicotine. Meaning for Sudden Infant Death Syndrome
Journal article   Open access   Peer reviewed

The Alteration of Neonatal Raphe Neurons by Prenatal-Perinatal Nicotine. Meaning for Sudden Infant Death Syndrome

Verónica J Cerpa, María de la Luz O Aylwin, Sebastián Beltrán-Castillo, Eduardo U Bravo, Isabel R Llona, George B Richerson and Jaime L Eugenín
American journal of respiratory cell and molecular biology, Vol.53(4), pp.489-499
10/2015
DOI: 10.1165/rcmb.2014-0329OC
PMCID: PMC4742896
PMID: 25695895
url
https://doi.org/10.1165/rcmb.2014-0329OCView
Published (Version of record) Open Access

Abstract

Nicotine may link maternal cigarette smoking with respiratory dysfunctions in sudden infant death syndrome (SIDS). Prenatal-perinatal nicotine exposure blunts ventilatory responses to hypercapnia and reduces central respiratory chemoreception in mouse neonates at Postnatal Days 0 (P0) to P3. This suggests that raphe neurons, which are altered in SIDS and contribute to central respiratory chemoreception, may be affected by nicotine. We therefore investigated whether prenatal-perinatal nicotine exposure affects the activity, electrical properties, and chemosensitivity of raphe obscurus (ROb) neurons in mouse neonates. Osmotic minipumps, implanted subcutaneously in 5- to 7-day-pregnant CF1 mice, delivered nicotine bitartrate (60 mg kg(-1) d(-1)) or saline (control) for up to 28 days. In neonates, ventilation was recorded by head-out plethysmography, c-Fos (neuronal activity marker), or serotonin autoreceptors (5HT1AR) were immunodetected using light microscopy, and patch-clamp recordings were made from raphe neurons in brainstem slices under normocarbia and hypercarbia. Prenatal-perinatal nicotine exposure decreased the hypercarbia-induced ventilatory responses at P1-P5, reduced both the number of c-Fos-positive ROb neurons during eucapnic normoxia at P1-P3 and their hypercapnia-induced recruitment at P3, increased 5HT1AR immunolabeling of ROb neurons at P3-P5, and reduced the spontaneous firing frequency of ROb neurons at P3 without affecting their CO2 sensitivity or their passive and active electrical properties. These findings reveal that prenatal-perinatal nicotine reduces the activity of neonatal ROb neurons, likely as a consequence of increased expression of 5HT1ARs. This hypoactivity may change the functional state of the respiratory neural network leading to breathing vulnerability and chemosensory failure as seen in SIDS.
Animals, Newborn Smoking - adverse effects Sudden Infant Death - pathology Maternal-Fetal Exchange Humans Infant Nicotine - toxicity Prenatal Exposure Delayed Effects - etiology Sudden Infant Death - etiology Pregnancy Animals Raphe Nuclei - drug effects Raphe Nuclei - pathology Female Mice Disease Models, Animal

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