Development of tolerance to ethanol-induced suppression of breathing movements and brain activity in the near-term fetal sheep during short-term maternal administration of ethanol.
The effect of short-term maternal ethanol administration on the ethanol-induced suppression of fetal breathing movements, electrocortical (ECoG) activity, and electroocular (EOG) activity was determined in the near-term fetal sheep. Twelve conscious instrumented pregnant ewes (between 125 and 139 days of gestation; term, 147 days) received 1-h intravenous infusion of 1 g ethanol/kg total body weight daily for six days (n = 6) or an equivalent volume of normal saline daily for six days (n = 6). On the seventh day, the ethanol- and saline-pretreated animals were administered 1 g ethanol/kg total body weight. A further six ewes received 1-h intravenous infusion of 1 g ethanol/kg total body weight (n = 3) or an equivalent volume of normal saline (n = 3) daily for thirteen days with both groups receiving 1 g ethanol/kg total body weight on day fourteen. Fetal ECoG and EOG activities, and fetal breathing movements were monitored continuously over the post- operative and experimental periods. Saline infusion had no significant effect on the parameters studied. Fetal breathing movements were suppressed for 8 h after the first ethanol dose, and were not significantly suppressed after fourteen days of once-daily, maternal ethanol administration. Low-voltage ECoG and EOG activities were suppressed for 3 h after the first ethanol dose, and were not significantly suppressed after seven days of repeated ethanol administration. Maternal and fetal blood gases and acid-base balance were not significantly affected by maternal ethanol administration. These data demonstrate that short-term maternal administration of ethanol results in the development of tolerance to ethanol in the mature fetus.
Smith
G N
GN
Lawson Research Institute, St. Joseph's Health Center, University of Western Ontario, London, Canada.
Brien
J F
JF
Carmichael
L
L
Homan
J
J
Clarke
D W
DW
Patrick
J
J
D000818:Animals; D001921:Brain / Q000187:drug effects / Q000196:embryology* / Q000502:physiology; D002540:Cerebral Cortex / Q000187:drug effects / Q000196:embryology / Q000502:physiology; D004361:Drug Tolerance; D004585:Electrooculography; D000431:Ethanol / Q000097:blood / Q000494:pharmacology*; D005260:Female; D005333:Fetus / Q000502:physiology*; D007700:Kinetics; D011247:Pregnancy; D011270:Pregnancy, Animal / Q000502:physiology*; D012119:Respiration / Q000187:drug effects*; D012756:Sheep; D009435:Synaptic Transmission / Q000187:drug effects
D000431:Ethanol