Effect of circadian rhythm disorder on cognitive decline and neurologic impairment after traumatic brain injury in rats / 局解手术学杂志

ABSTRACT

Objective To explore the effect of circadian rhythm disorder on cognitive decline and neurologic impairment after traumatic brain injury (TBI) in rats.Methods Rats were subjected to a weight-drop model of TBI,then the rat models were divided into 2 groups ac-cording to the environmental length of day and night ,namely,the whole day group (12 h light/12 h light) and the control group (12 h light/12 h dark).After 14 days,the Morris water maze test and step-down test were carried out to evaluate the memory of the rats in each group . HE staining and immunohistochemistry ( BrdU, Ki-67) were carried out to evaluate the degree of the neurologic impairment of the rats in each group.And the mRNA expressions of Caspase-3,Caspase-9,Bcl-2 and Bax were evaluated with realtime PCR .Results The memory function of the rats in whole day group was significant lower than control group ;the damage degree of the cells in the hippocampus and the cortical lesion volume in whole day group were significant higher than control group ;the cell proliferation rate and newborn cell survival rate in the whole day group decreased significantly compared with the control group ;the mRNA expression of Bcl-2 in whole day group was signifi-ant lower than control group ,and the mRNA expression of Caspase-3,Caspase-9 and Bax in whole day group was signifiant higher than control group.Conclusion Circadian rhythm disorder can worsen TBI-induced cognitive decline and neurologic impairment .