Mario Órdenes S.; German Espinoza R.; Benjamín Henríquez M.; Thomas Cabezas B.; Hugo Tapia G.; Wendy Donoso T. & Héctor González C.

The early postnatal period is characterized by rapid brain growth, possibly related to variations in tissue oxygen. This has motivated the study of protocols that supply different intermittent oxygen concentrations, to observe their morphological and cerebral effects. Fifty-two pups Sprague-Dawley rats were distributed in equal numbers into four experimental groups, Control (C, 21 %O ), Intermittent Hypoxia (HI, 11 %O ),22 Intermittent Hyperoxia (HOI, 30 %O ) and Intermittent Hypoxia 2 Hyperoxia (HHI, 11 % - 30 %O2). The protocols considered 5 cycles of 5 min of dosing, for 50 min diary. It was performed in a semi- hermetic chamber between 5 to 11postnatal days. The evaluations of body growth and neuronal quantification were analyzed in male pups, on postnatal day 28. Body weight in the intermittent hypoxia group showed significant differences compared to the intermittent hyperoxia group (HI vs HOI, p<0.01) and the intermittent hypoxia- hyperoxia group (HI vs HHI, p<0.001). Body size decreased in the Intermittent hypoxia-hyperoxia group with significant differences compared to the control group (C vs HHI, p<0.05) and with respect to the intermittent hypoxia group (HHI vs HI, p<0.01). The neuronal count in the area CA1 of the hippocampus increased in the intermittent hypoxia group with significant differences compared to the control groups (C vs HI; p<0.05), to the intermittent hyperoxia group (HI vs HOI; p< 0.001) and the intermittent hypoxia-hyperoxia group (HI vs HHI; p<0.001). Finally, the intermittent hypoxia- hyperoxia group decreased significantly in the number of neurons compared with the intermittent hyperoxia group (HHI vs HOI; p<0.001). Intermittent hypoxia showed beneficial results in body growth and the number of neurons in the CA1 area of the hippocampus, in contrast, intermittent hypoxia-hyperoxia experienced adverse results with a decrease in these variables, in the early postnatal period of the rat.

ÓRDENES, S. M.; ESPINOZA, R. G.; HENRÍQUEZ, M. B.; CABEZAS B. T.; TAPIA, G. H.; DONOSO, T. W.; GONZÁLEZ, C. H. Intermittent oxygen concentrations have an impact on the early postnatal development of Sprague-Dawley rats: EffectsonhippocampalCA1. Int. J.Morphol., 41(1):59-64,2023.