Influence of different levels of neonatal mild/moderate hypoxia-ischemia in learning abilities of rats at the age of one month.
We studied the effects of mild/moderate hypoxia-ischemia in 90 newborn Wistar rats divided into 3 groups. Two of the three groups were submitted to two different levels of hypoxia (FiO2 = 0.05, group F5 and FiO2 = 0.1, group F10) and the third to normoxia (FiO2 = 0.21, group F21) in a thermoneutral and controlled environment. We examined their influence in a maze test 1 month later after two training trials, a 48-hour fasting period and handling stress just before starting the trial. The learning ability in animals exposed to FiO2 = 0.1 was lower (significantly higher number of squares crossed F10 = 37.57 +/- 20.8) than the others (F21 = 26.22 +/- 19.25; F5 = 26.56 +/- 14.97; p = 0.0481), while group F5 had the best learning improvement measured by the reduction in wrongly crossed squares (F5 day 25 = 25.08 +/- 19.9; day 26 = 13.04 +/- 13.91; day 30 = 10.08 +/- 9.66; p = 0.0427). These differences in group F5 as well as the maze solution profile (defined by analysis of 15 variables considered) was significantly closer to the control group F21 than the less hypoxied group F10. We discuss whether these paradoxical results in learning abilities reflect the influence of the hypoxic levels to which the newborn animals were submitted, or to the effects of uncontrolled variables in this study.
Carratalá
F
F
Pediatric Department, Faculty of Medicine, University of Alicante, Spain.
Moya
M
M
Ferrer
E
E
D000818:Animals; D000831:Animals, Newborn; D001522:Behavior, Animal / Q000502:physiology*; D002545:Brain Ischemia / Q000503:physiopathology*; D015331:Cohort Studies; D002534:Hypoxia, Brain / Q000503:physiopathology*; D018782:Maze Learning / Q000502:physiology*; D051381:Rats; D017208:Rats, Wistar; D012016:Reference Values; D013997:Time Factors