The Research On The Mechanism Of Anxiolyticlike And Antidepressant-like Effects Of YL-IPA08,a Selective Ligand For TSPO

18 ku translocator protein?TSPO?,previously known as peripheral-type benzodiazepine receptor,mainly localized in outer mitochondrial membrane of glial cells in the brain.It is supposed to be a new potential target for therapy in anxiety and depression disorders in recent years.The cholesterol translocates from the outer to the inner mitochondrial membrane by TSPO,then converts to neurosteroids?such as allopregnanolone?by a series of enzymatic-reactions.The neurosteroids can regulate emotions by acting on the GABAA receptors.AC-5216 is recognized as the TSPO selective ligand internationally,which is insoluble in water and has low bioavailability,however.YL-IPA08 is synthesized on the basis of AC-5216 with structure optimization by institute of Pharmacology and Toxicology,academy of military medical science.It has higher affinity and selectivity on TSPO with water solubility and higher bioavailability compared with AC-5216.YL-IPA08 exerted anxiolytic-like,antidepressant-like effects and treating PTSD activity in the rodent models via increasing the synthesis of allopregnanolone in the brain.This present study intends to investigate the anxiolytic-like and antidepressant-like effects of YL-IPA08 on the zebrafish models and the protective effect of YL-IPA08 on corticosterone?CORT?-induced apoptosis of BV-2,which have important values on studying TSPO and the mechanism of its ligand.We applys the novel tank test,light/dark test and mirror test to detect the behavioral effects of zebrafish with YL-IPA08 8-day chronic treatment for 30 min each day.In vitro,BV-2 was pretreated with YL-IPA08 and?or?TSPO antagonist PK11195 for 2 h,then co-treated with CORT for another 24 h.The apoptosis rate was measured by flow cytometry;CCK-8 kit was used to test BV-2 cell viability;the protein expression of TSPO was determined by Western blotting;the level of allopregnanolone was detected by ELISA kit.The research results are as the followings:?1?Compared with the normal control group,the zebrafish in the YL-IPA08 0.012 mg·L^-1 group spent more time in the up half area of the tank and transited more times by up and down in the first 6min of the novel tank test without alterations in the locomotion activity?P<0.05?;Similarly,in the first 6 min of the dark/light test,the zebrafish spent more time in the light area?P<0.05?and less time in the dark area?P<0.05?in the YL-IPA08 0.012mg·L^-1 group;In the first 6 min of the mirror test,the zebrafish spent less time?P<0.05?and travels less diatances?P<0.05?in the center area of the mirror test in the YL-IPA08 0.012 mg·L^-1 group,but no transition less times;?2?Compared with the vehicle group,the cell apoptosis rate in line with positive drug-AC-5216 was significantly decreased in YL-IPA08 1¹00 nmol·L^-1 and CORT co-treatment group?P<0.01?,especially in YL-IPA08 100 nmol·L^-1 group,which were antagonized by PK11195 100 nmol·L^-1 treatment?P<0.05?.Cell viability was increased in YL-IPA08 100 nmol·L^-1 and CORT co-treatment group by CCK-8?P<0.01?,which were blocked by PK11195 100 nmol·L^-1 treatment?P<0.01?;The expression of TSPO and the level of allopregnanolone were enhanced in YL-IPA08 100 nmol·L^-1and CORT co-treatment group by Western blotting?P<0.05?and ELISA kit?P<0.01?,respectively.And the increasement of allopregnanolone caused by YL-IPA08 was blocked by PK11195 100 nmol·L^-1 treatment?P<0.05?.The results above suggested that YL-IPA08 exerts anxiolytic-like and antidepressant-like effects in the zebrafish models and protects BV-2 cells from CORT-induced apoptosis,The behavioral effects of YL-IPA08 may be conferred by increasing level of and allopregnanolone and protecting glial cells.