Long-term influence of perinatal asphyxia on the social behavior in aging rats.

Background: Various groups have been addressing the question of whether perinatal asphyxia (PA) affects the behavior of young animals, but no information is available on long-term effects of PA on the behavior in aged rats, although it has been postulated that PA may lead to neurological and psychiatric deficits in adult life.

Objective: We, therefore, decided to study the effects of PA on social and anxiety-related behaviors in 2-year-old rats, using a noninvasive animal model resembling the clinical situation.

Methods: For the behavioral studies, the open-field test, the elevated plus-maze test, and a social interaction test in pairs were performed. Magnetic resonance imaging of the brain was selected to rule out neuropathological changes due to the aging process per se, as well as asphyxia-induced pathologies in the brain areas known to play an important role in the modulation of behavior.

Results: The social interaction test revealed a statistically significant increase in the number of social grooming episodes and the time spent running alone, whereas the numbers of social sniffing and fighting episodes and the time spent running together were decreased in the asphyxiated group. The elevated plus- maze test revealed a higher presence of entries into the closed arm. Furthermore, sniffing and self-grooming episodes were significantly increased in the asphyxiated group.

Conclusions: We found a significantly decreased social aggressiveness and an increased social contact behavior as well as increased anxiety levels in the asphyxiated animals. The present findings may provide important information on the long-term behavioral sequelae of PA in the aged individual.