The first breaths of air stimulate noradrenaline turnover in the brain of the newborn rat.
The aim of this study was to analyse the noradrenaline (NA)-turnover in the brain around birth and its significance for neonatal adaptation. NA and its metabolite 3-methoxy-4-hydroxyphenylethylene glycol (MHPG) have been measured by high-pressure liquid chromatography (HPLC) in the pons-medulla and cortex in rat foetuses and pups. The MHPG/NA ratio was used as an index of NA-turnover. Catecholamines were also determined in the adrenals for comparison. The MHPG/NA ratios were found to increase 2.7-fold in the pons-medulla and 2-fold in the cortex during the first day after birth. The surge of NA-turnover occurred after the pups had been breathing air for two hours. The increase of NA-turnover was significantly lower in the cortex of rat pups breathing a hypoxic gas mixture or when they were kept in a cooler environment. The differences were less marked in the pons-medulla. We conclude that breathing air stimulates NA-turnover in the brain of the newborn rat and this stimulatory effect is modulated by environmental factors.
Lagercrantz
H
H
Department of Paediatrics, Karolinska Institute, Stockholm, Sweden.
Pequignot
J
J
Pequignot
J M
JM
Peyrin
L
L
D000818:Animals; D000831:Animals, Newborn; D001921:Brain / Q000378:metabolism*; D008734:Methoxyhydroxyphenylglycol / Q000378:metabolism; D009638:Norepinephrine / Q000378:metabolism*; D051381:Rats; D011919:Rats, Inbred Strains; D012119:Respiration / Q000502:physiology*; D014018:Tissue Distribution
D008734:Methoxyhydroxyphenylglycol; D009638:Norepinephrine