The Neuroprotective Role And Mechanism Of Adjudin In Experimental Traumatic Brain Injury

Objective: Adjudin,a small molecular compound which is used as a male contraceptive,has been reported that it may have neuroprotective effect.However,its function on traumatic brain injury(TBI)has not been assessed.Hence,we investigated the effects of adjudin on cerebral edema and neurological function using a mouse model of TBI and explored the underlying mechanisms.Methods: Adult male C57BL/6 mice were random grouped and received controlled cortical impact(CCI)injury or sham-operation,then the adjudin-treatment group accepped an injection of adjudin(50 mg/kg).We assessed the neurological function deficit using mNSS,Rotarod and Morris Water Maze test.Three days after the CCI injury,through MRI scaning,we evaluated the severity of brain edema(T2WI sequence),identified the main type of brian edema(ADC mapping),and assessed the permeability of BBB(DCE-MRI).After the mice were euthanized 3 days post-CCI injury,the samples were collected for further analysis.The water content of brain tissue was calculated by using the dry and wet weighing method,and the BBB integrity was evaluated via Evansblue extrvasation and expression of tight junction protein.By using the experimental methods of real-time PCR,western blot and Immunostaining,the expression of AQP4,the release of inflammatory cytokine,the activation of neurological inflammatory cell and the interaction between adjudin and NF-?B pathway was explored and evaluated.Cultured LPS-stimulated primary mouse astrocytes were used for detecting inflammatory cytokines in vitro experiments.Result: Adjudin improved mNSS,Rotarod and Morris Water Maze test outcomes after CCI injury.Besides,compared with vehicle group,adjudin treatment significantly reduced cerebral edema volume,alleviated cytotoxic cerebral edema and reduced the permeability of BBB on day 3 post-CCI injury.Additionally,adjudin treatment significantly reduced the extravasation of Evans blue and ameliorated the expressive reduction of tight junction proteins on day 3 post-CCI injury.Furthermore,adjudin treatment significantly decreased the gene and protein expression of aquaporin 4 and attenuated the activation of microglia and astrocytes in post-injury mice.Adjudin could also inhibit the release of inflammatory cytokine in both mice and cultured astrocytes.The Western blot results of the peritraumatic protein samples demonstrated that adjudin significantly blocked the phosphorylation of IKK?,I?B?/?,and NF-?B p65,which resulted in a reduction of NF-?B p65 nuclear translocation.Conclusion: Small molecule drug adjudin can effectively promote motor and cognitive function of mice after TBI.Adjudin treatment attenuated the development of TBIinduced cerebral edema and allevated BBB disruption.The underlying mechanism of these function at least partly include the inhibiting effect of adjudin in NF-?B pathway,which can result in the inhibition of the process of infalammation.That will further attenuate the activation of astrocytes and reduce the expression of AQP4 on its endfeet,which can alleviate the swollen of astrocytes and finally attenuate cerebral edema.These findings suggest that adjudin is a potential therapeutic intervention preventing the development of cerebral edema and improving neurological function after TBI.