Objective: To investigate the effect of RGFP966, a histone deacetylase 3 (HDAC3) inhibitor, on cognitive function in mice with sepsis-associated encephalopathy (SAE).
Methods: Forty adult male C57BL/6 mice, aged 2 months and weighing 25-30 g, were randomly divided into four groups: sham surgery group (group SS), SAE model group (group MS), sham surgery + RGFP966 group (group SR), and SAE model + RGFP966 group (group MR), 10 mice in each group. Mice in groups SS and SR underwent abdominal incision with cecal exposure but no ligation or puncture. Mice in groups MS and MR received cecal ligation and puncture (CLP) to establish the SAE model. Mice in groups SR and MR were administered RGFP966 20 mg/kg subcutaneously daily for 14 consecutive days starting from the day of surgery, while those in groups SS and MS received an equal volume of normal saline. On postoperative day 17, total moving distance was measured using the open-field test. On postoperative day 18, the novel object recognition test was performed to record the discrimination index. On postoperative day 20, the Y-maze test was conducted to record the number of arm entries and calculate the percentage of spontaneous alternation. The protein levels of HDAC3, nuclear factor-κB p65 subunit (p65), acetylated p65 (Ac-p65), ionized calcium-binding adaptor molecule 1 (Iba-1), interleukin-1β (IL-1β), and tumor necrosis factor-α (TNF-α) in the hippocampus were detected by Western blot. Immunofluorescence staining was used to evaluate the co-localization of HDAC3, Iba-1, and CD68 in the hippocampal CA1 region.
Results: Compared with group SS, group MS exhibited significantly decreased discrimination index, percentage of spontaneous alternation, and hippocampal Ac-p65 protein level, as well as significantly increased protein levels of HDAC3, p65, Iba-1, IL-1β, and TNF-α in the hippocampus, and the mean fluorescence intensity of HDAC3 in Iba-1+cells and the area of CD68 in Iba-1+cells in the CA1 region were also significantly elevated in group MS (P < 0.05). Compared with group MS, group MR showed significantly increased discrimination index, percentage of spontaneous alternation, and Ac-p65 protein level, along with markedly decreased protein levels of HDAC3, p65, Iba-1, IL-1β, and TNF-α in the hippocampus, and the mean fluorescence intensity of HDAC3 in Iba-1+cells and the area of CD68 in Iba-1+cells in the CA1 region were significantly reduced in group MR (P < 0.05).
Conclusion: The HDAC3 inhibitor RGFP966 can ameliorate cognitive dysfunction in SAE mice. The mechanism may be related to the downregulation of HDAC3 expression in microglia, thereby inhibiting microglial activation and the subsequent inflammatory response. |
