Cooling and asphyxia differentially affect augmented noradrenaline turnover in the brain of the externalized rat foetus.
The object was to investigate the effect of various perinatal conditions particularly cooling and asphyxia on the noradrenaline (NA) turnover in the foetal rat brain. The ratios between the noradrenergic metabolite 3-methoxy-4-hydroxy phenyl-ethylene glycol-sulphate (MHPG) and noradrenaline were determined as indexes of NA-turnover in the cortex and the pons-medulla of the foetal rat brain using high pressure liquid chromatography (HPLC). Rat foetuses were externalized by caesarean section performed on a spinally anaesthesized highly pregnant rat mother. One uterine horn was used as control while the other was exposed to externalization, simulated uterine contractions, cooling or asphyxia. Externalization per se and simulated uterine contractions did not cause any significant change in the NA-turnover. Cooling at 25 degrees C for 20 min caused a significant increase in NA-turnover in the cortex while a significant decrease was observed after 10 min of asphyxia in both the cortex and the pons-medulla and after 15 min in the cortex. We conclude that externalization and simulated uterine contractions per se do not seem to affect the augmented NA-turnover at birth. Cooling caused an increase suggesting a potentiating role on NA-turnover in conjunction with the externalization. On the other hand NA-turnover was depressed by asphyxia, suggesting that the level of oxygen is important for NA neuron activity.
Ehrström
M
M
Department of Woman and Child Health, Karolinska Hospital, Stockholm, Sweden.
Pequignot
J
J
Pequignot
J M
JM
Lagercrantz
H
H
D000818:Animals; D001237:Asphyxia / Q000378:metabolism*; D001921:Brain / Q000378:metabolism*; D002851:Chromatography, High Pressure Liquid; D003080:Cold Temperature; D005260:Female; D005315:Fetal Diseases / Q000378:metabolism*; D005333:Fetus / Q000378:metabolism*; D008734:Methoxyhydroxyphenylglycol / Q000378:metabolism; D009638:Norepinephrine / Q000378:metabolism*; D011247:Pregnancy; D051381:Rats / Q000196:embryology; D017207:Rats, Sprague-Dawley; D014590:Uterine Contraction / Q000502:physiology
D008734:Methoxyhydroxyphenylglycol; D009638:Norepinephrine