Traumatic brain injury in late adolescent rats: Effects on adulthood memory and anxiety.

Abstract

The consequences of traumatic brain injury (TBI) sustained during late adolescence (7 weeks old) on spontaneous object recognition memory and on anxiety-like behaviors in the elevated plus maze were tested in rats during adulthood. Testing took place at 2 different postinjury times, in separate groups: 3 and 6 weeks, when animals were 10 and 13 weeks old, respectively. The rats were either submitted to controlled cortical impact injury, an experimental model of focal TBI with contusion, or were sham-operated. TBI animals failed to remember the familiar object and had a significantly lower performance than sham-operated animals, indicating memory disruption, when the retention delay was 24 hr, but not when it was 3 hr. TBI did not have any significant effect on the main anxiety-related behaviors, but it reduced time in the central platform of the elevated plus maze. The effects of TBI on memory and on anxiety-like behaviors were similar at the 2 postinjury times. In both TBI and sham-operated groups, animals tested 6 weeks after surgery had lower anxiety-related indices than those tested at 3 weeks, an effect that might be indicative of reduced anxiety levels with increasing age. In summary, focal TBI with contusion sustained during late adolescence led to object recognition memory deficits in a 24-hr test during adulthood but did not have a major impact on anxiety-like behaviors. Memory deficits persisted for at least 6 weeks after injury, indicating that spontaneous modifications of these functional disturbances did not take place along this time span.

Posttraining Epinephrine Reverses Memory Deficits Produced by Traumatic Brain Injury in Rats

“…Moreover, performance of TBI-0 group was significantly lower than that of Sham groups. This deficit is consistent with previous results using object recognition memory in rodents [ 18 , 19 , 21 – 26 ] and also with other studies with different behavioral procedures in both humans and animals, thus showing that anterograde amnesia is a common sequel of TBI [ 3 , 17 ]. The group differences in behavioral outcome were not likely due to differences in anxiety when faced with a new object or in exploration times during acquisition or retention sessions, as no differences between groups were observed when these variables were analyzed.…”

“…In the present experiment, among the different animal models developed to reproduce the spectrum of pathological changes of human TBI, a controlled cortical impact (CCI) was used. CCI has been widely used in animal research [ 16 ] and produces similar deficits of human TBI, such as learning and memory deficits [ 16 , 17 ], including deficits in object recognition task [ 18 , 19 ].…”

Prediction of Post-Concussive Behavioral Changes in a Rodent Model Based on Head Rotational Acceleration Characteristics

“…However, high variability is a limitation common to most in vivo studies, particularly in the area of animal behavior. The coefficients of variation for similar EPM metrics from other concussion studies were consistent with the current findings (35 to 68% for open area duration),22,33 and in some cases exceeded 100% 1. Therefore, somewhat weak correlations were expected due to the inherent variability of rodent behavioral data.…”

Role of Dopamine 2 Receptor in Impaired Drug-Cue Extinction in Adolescent Rats

“…1 ). In the rat, P28–P56 is widely accepted as adolescence, with P70 as the onset of young adulthood ( Spear 2000 ; Amorós-Aguilar et al 2015 ; Saul et al 2015 ). This relatively small developmental window is one of the reasons that preclinical adolescent addiction research is difficult to carry out.…”