Objective To explore the effect of dexmedetomidine (Dex) on human astrocytes duing ischemic stroke (IS) using an in vitro oxygen glucose deprivation (OGD) model, and explore the potential mechanisms. Methods According to the random number table method, human astrocytes were divided into ten groups (n=3): a Control group, an OGD group, 0.5, 1.0 μmol/L and 2.0 μmol/L Dex treatment plus OGD groups (0.5 μmol/L Dex+OGD group, 1.0 μmol/L Dex+OGD group, and 2.0 μmol/L Dex+OGD group), an OGD plus 200 nmol/L K‑252a [brain derived neurotrophic factor (BDNF) inhibitor] (OGD+K‑252a) group, an OGD plus 1.0 μmol/L Dex (OGD+Dex) group, an OGD plus 1.0 μmol/L Dex and 200 nmol/L K‑252a (OGD+Dex+K‑252a) group, a 200 nmol/L K‑252 (K‑252a) group using normal cells and a 200 nmol/L K‑252a and 5 μmol/L BAY11‑7082 [NOD like receptor thermal protein domain associated protein 3 (NLRP3) inhibitor] (K‑252a+BAY11‑7082) group using normal cells. After treatment for 24 h, the protein levels of BDNF, NLRP3, active caspase‑1, and gasdermin D (GSDMD)‑N were detected by Western blot. The contents of interleukin (IL)‑1β and IL‑18 were measured by enzyme‑linked immunosorbent assay (ELISA). The levels of reactive oxygen species (ROS) were detected by 2',7'‑dichlorofluorescin diacetate (DCFDA) method. The changes in cell pyroptosis were detected by flow cytometry. Results Compared with the Control group, the OGD group showed increases in the contents of IL‑1β and IL‑18, ROS fluorescence intensity, cell pyroptosis rate, and the protein levels of NLRP3, active caspase‑1 and GSDMD‑N (all P<0.05), and decreases in BDNF protein levels (P<0.05); the 0.5 μmol/L Dex+OGD group presented increases in IL‑18 content, ROS fluorescence intensity, and cell pyroptosis rate (all P<0.05); the 1.0 μmol/L Dex+OGD group and the 2.0 μmol/L Dex+OGD group showed increases in ROS fluorescence intensity and cell pyroptosis rate (all P<0.05); and the K‑252a group presented increases in the contents of IL‑1β and IL‑18, cell pyroptosis rate, and the protein levels of NLRP3, active caspase‑1 and GSDMD‑N (all P<0.05). Compared with the OGD group, decreases were found as to the contents of IL‑1β and IL‑18, ROS fluorescence intensity, and cell pyroptosis rate in the 0.5 μmol/L Dex+OGD group, the 1.0 μmol/L Dex+OGD group, and the 2.0 μmol/L Dex+OGD group (all P<0.05); the protein levels of BDNF increased in the 1.0 μmol/L Dex+OGD group and the 2.0 μmol/L Dex+OGD group (all P<0.05); the protein levels of NLRP3 decreased in the 0.5 μmol/L Dex+OGD group and the 1.0 μmol/L Dex+OGD group (all P<0.05); the protein levels of caspase‑1 decreased in the 1.0 μmol/L Dex+OGD group and the 2.0 μmol/L Dex+OGD group (all P<0.05); the protein levels of GSDMD‑N decreased in the 0.5 μmol/L Dex+OGD group, the 1.0 μmol/L Dex+OGD group and the 2.0 μmol/L Dex+OGD group (all P<0.05); the OGD+K‑252a group showed increases in the contents of IL‑1β and IL‑18, ROS fluorescence intensity, cell pyroptosis rate, and the protein levels of NLRP3, active caspase‑1 and GSDMD‑N (all P<0.05), and decreases in BDNF protein levels (P<0.05); and the OGD+Dex group presented decreases in the contents of IL‑1β and IL‑18, ROS fluorescence intensity, cell pyroptosis rate, and the protein levels of NLRP3, active caspase‑1 and GSDMD‑N (all P<0.05), and increases in BDNF protein levels (P<0.05). Compared with the OGD+Dex group, the OGD+Dex+K‑252a group showed increases in the contents of IL‑1β and IL‑18, ROS fluorescence intensity, cell pyroptosis rate, and the protein levels of NLRP3, active caspase‑1, and GSDMD‑N (all P<0.05), and decreases in BDNF protein levels (P<0.05). Compared with the K‑252a group, the K‑252a+BAY11‑7082 presented reduction in the contents of IL‑1β and IL‑18, cell pyroptosis rate, and the protein levels of NLRP3, activated caspase 1 and GSDMD‑N (all P<0.05). Conclusions Dex relieves OGD‑induced astrocyte inflammation and pyroptosis through inducing the release of BDNF and suppressing the overactivation of the NLRP3 pathway.