Prefrontal dopaminergic system and its role in working memory and cognition in spinal cord-injured rats

Abstract

New Findings What is the central question of this study?How does spinal cord injury affect prefrontal cortex function and the expression of dopamine receptors? What is the main finding and its importance?Spinal cord injury impaired cognitive function, which was associated with reduced dopamine receptor expression in the prefrontal cortex. The effect of spinal cord injury (SCI) has been studied widely in paraplegia and motor areas of the brain, but its mechanisms in memory and cognitive impairment remain controversial. Here, we focused on the impact of SCI on prefrontal performance via dopamine levels and receptors. We divided 18 male rats into three groups, i.e. control, laminectomy and SCI groups. Laminectomy and SCI were induced at T10 of the spinal cord. One week later, after locomotor recovery, the novel object recognition and T-maze (spontaneous alternation) tests were applied. After behavioural assessments, the rats were killed and their brain tissues harvested. According to the behavioural findings, cognitive function was impaired in the SCI group (P < 0.05). Also, SCI significantly increased the dopamine level and decreased the expression of dopamine receptors in the prefrontal cortex 2 weeks after injury (P < 0.05). Given the role of dopamine in cognition, SCI could impair novel object recognition and spatial working memory via dopaminergic systems.