Depression-like and anxiety-like behavioural aftermaths of impact accelerated traumatic brain injury in rats: a model of comorbid depression and anxiety?

Depression and anxiety tend to be the most prevalent conditions among the multitude of neurobehavioural disorders which cause distress in the survivors of traumatic brain injury (TBI). The objective of the present investigation was to examine depression-like and anxiety-like behaviour of rats following diffuse TBI. Impact accelerated TBI was induced in anaesthetised rats by a modified weight drop method. TBI and sham-operated rats received either a chronic (14 days) regimen of escitalopram (5-20 mg/kg) or vehicle, following which they were subjected to a behavioural test battery. The results evince the depression-like behaviour of TBI rats in modified open field exploration, hyperemotionality, socio-sexual interaction and elevated plus-maze exploration paradigms. In addition, an anxiety-like behaviour was evident in social interaction and marble-burying tests. Chronic escitalopram (10 and 20 mg/kg) treatment significantly attenuated the TBI associated behavioural deficits. In conclusion, the aforesaid behavioural anomalies observed in TBI rats are analogous to comorbid anxiety and depression in humans. These findings substantiate the TBI rats as a candidate model of comorbid anxiety and depression.