Objective To investigate the effect and mechanism of suberoylanilide hydroxamic acid (SAHA) on the fear extinction in mice with chronic social defeat stress (SD). Methods Fifty-six male C57BL/6J mice aged 7-8 weeks were randomly divided into control group,social defeat group,control-SAHA group and social defeat-SAHA group to investigate the effect of SAHA and social defeat group,social defeat-AAV BDNF group and social defeat-AAV blank group to investigate the effect of BDNF. Fear extinction in mice was evaluated by fear conditioning test (FC). The levels of BDNF and HDAC2 in mice hippocampus were detected by Western blot (WB). The expression of BDNF-overexpressing virus in hippocampus of mice was detected by immunofluorescence assay. Results (1) Compared with control group,fear extinction in the social defeat group was significantly decreased (P<0. 05). Compared with control group, the level of HDAC2(0. 50±0. 02) in the social defeat group was significantly increased (P<0. 001),while the level of BDNF(0. 16 ± 0. 03) was significantly decreased (P<0. 001) in the social defeat group. ( 2) After using SAHA,fear extinction of mice significantly improved (P<0. 05). Compared with control group,the level of HDAC2 (0. 26±0. 02) in the control-SAHA group was significantly decreased(P<0. 001),and the level of BDNF (0. 40±0. 03) was significantly increased (P<0. 001). Compared with social defeat group,the level of HDAC2 (0. 39±0. 03) in the social defeat-SAHA group was significantly decreased (P<0. 001),and the lev-el of BDNF (0. 28±0. 01) was significantly increased (P<0. 001). (3)After injection BDNF-overexpressing virus,fear extinction was significantly improved(P<0. 05). Conclusion SAHA can enhance fear extinction in mice with chronic social defeat stress and its mechanism may be related to the up-regulation of BDNF ex-pression in hippocampus by inhibiting HDAC2 in hippocampal.

Chronic refractory wound (CRW) is one of the most challengeable issues in clinic due to complex pathogenesis, long course of disease and poor prognosis. Experts need to conduct systematic summary for the diagnosis and treatment of CRW due to complex pathogenesis and poor prognosis, and standard guidelines for the diagnosis and treatment of CRW should be created. The Guideline forthe diagnosis and treatment of chronic refractory wounds in orthopedic trauma patients ( version 2023) was created by the expert group organized by the Chinese Association of Orthopedic Surgeons, Chinese Orthopedic Association, Chinese Society of Traumatology, and Trauma Orthopedics and Multiple Traumatology Group of Emergency Resuscitation Committee of Chinese Medical Doctor Association after the clinical problems were chosen based on demand-driven principles and principles of evidence-based medicine. The guideline systematically elaborated CRW from aspects of the epidemiology, diagnosis, treatment, postoperative management, complication prevention and comorbidity management, and rehabilitation and health education, and 9 recommendations were finally proposed to provide a reliable clinical reference for the diagnosis and treatment of CRW.