Establishment and evaluation of model of depression after traumatic brain injury

Objective To discuss about the establishment of mental depression model by traumatic brain injury in rats,and to evaluate the validity of this model.Methods The study was carried out in the experiment center of Wuhan University.A total of 48 male adult Wistar rats were randomized ( random number) into four groups ( n =12,each):( 1 ) in sham operation group,six rats were fed normally in one cage; (2) in model group,the model of the left frontal lobe contusion was made up by hitting with free-fall method on the left cortex of the rat,and subsequently the each of model rats were separately fed in a cage and put them in a lonely environment with chronic stress one week after traumatic brain injury in order to induce them into models of mental depression; ( 3 ) in brain trauma group,the trauma model of the left frontal lobe contusion was set up by the same procedure as in model group,and six rats were fed together in one cage; (4) in CUMS group,each rat was fed normally in one cage in a lonely environment after brain trauma made and chronic mild chaotic stress unpredictable to rats was given to induce mental depression.The consumption of sucrose water and the change of animal behavior were observed and the high performance liquid phase electrochemical with fluorescence detector was used to detect the biogenic monoamine neurotransmitter content (dopamine,serotonin and norepinephrine) in the hippocampus,prefrontal cortex,hypothalamus and striatum area in each group.Experimental data were processed with single factor analysis or t test of variance by Statistical Program for Social Sciences Version 13.0 (SPSS13.0) software.P ＜0.05 was considered as statistically significant difference.Results After modeling,the rats of four groups were examined by behavioral tests.It was found that the amount of sugar-water consumption by the rats in the model group and CUMP group decreased,implying the absence of interest in eating and anhedonia of the rats in these groups.In open-field test,the rats in the model group,CUMP group and brain trauma group showed reduction in square crossing and rearing,implying the under-activity and absence of interest in activity.In the water maze test,it was found that the rats in the model group,CUMP group and brain trauma group needed much time to reach the end-point and made many errors,implying the lowering ability to learn and memorize.Levels of dopamine,serotonin and norepinephrine in the hippocampus,prefrontal cortex,hypothalamus and striatum area decreased in these rats with traumatized brain in three groups especially in model group and CUMP group.Conclusions It is a valid method for establishing the mental depression model in rats by traumatic brain injury with separately feeding in the lonely environment and given chronic mild chaotic stress unpredictable to rats on the setting of the left frontal lobe contusion. Key words: Traumatic brain injury; Depression; Animal model; Monoamine neurotransmitter; Morphology