engleski

Effects of neonatal normobaric hypoxia on rat behavior at young and adult age

Prenatal hypoxia is one of the main causes of neonatal hypoxic-ischemic encelopathy which can result in a wide range of consequences, from severe mental retardation, cerebral palsy, and epilepsy to milder learning difficulties and behavioral disorders. Studies on rat models are necessary for understanding the behavioral outcomes of hypoxic brain injuries of different intensities, and their molecular basis. Our research group is trying to develop a non- invasive model of rat neonatal hypoxia, which corresponds to human prenatal hypoxia in midgestation (23-32 weeks of pregnancy). The aim of this study was to determine possible changes in locomotion, learning, anxiety-like, exploratory and social behavior in young rats neonatally exposed to normobaric hypoxia, as well as their persistence in the adulthood. On the first postnatal day (PND1), experimental pups (36 Wistar rats, both sexes) were kept under hypoxic conditions, which were induced in a warm (≈ 25°C) normobaric chamber (8% O2, 92% N2) during 2 hours. Controls (40 Wistar rats, both sexes) were kept in normal housing conditions. Rats underwent the battery of behavioral tests: open field, hole- board, T- maze and social choice from PND33 to PND45. 17 control and 15 hypoxic rats were retested from PND70 to PND82. In comparison to the control group, young hypoxic rats displayed highly significant increase in the number of rearings in the open field test and highly significant decrease in the number of nose pokes in a hole board test, indicating increased alertness and neophobia in an open space. Adult rats still had significantly increased number of rearings, but there were no differences in exploratory behavior. Our results suggest that neonatal exposure of rats to decreased oxygen levels may induce behavioral impairments at young age, represented as increased aspects of anxiety- like behavior which, in a milder form, persist in the adulthood.

non-invasive ; rearing ; exploratory behavior ; prenatal

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