BACKGROUND: Grape seed extract can inhibit chondrocyte apoptosis and aging, and improve osteoarthritis. However, the effects of grape seed extract on the apoptosis of chondrocytes in the growth plate and tibial growth are still unclear. OBJECTIVE: To investigate the effect of grape seed extract on interleukin-1β-induced apoptosis in rat growth plate cells and on tibial bone growth. METHODS: (1) Cell experiment: Growth plate chondrocytes from Sprague-Dawley rats were isolated, cultured, and identified. The cells were then randomly divided into control group, model group, grape seed extract group, miR-138-5p NC group and miR-138-5p inhibitor group. In the model group, 20 ng/mL interleukin-1β was used to induce apoptosis in rat growth plate chondrocytes. In the grape seed extract group, 20 ng/mL interleukin 1β was added along with 10 μmol/L grape seed extract solution for 48 hours. Cells in the miR-138-5p NC and inhibitor groups were transfected with 5 nmol/L miR-138-5p NC and 5 nmol/L miR-138-5p inhibitor for 12 hours, respectively, followed by addition of 20 ng/mL interleukin-1β. qRT-PCR was used to detect miR-138-5p and caspase-3 expression. Luciferase reporter assay was used to analyze the relationship between miR-138-5p and caspase-3 targeting. Cell counting kit-8 was used to detect cell proliferation activity. Flow cytometry was used to detect cell apoptosis. Caspase-3 and Bcl-2 protein expressions were detected by western blot. (2) Animal experiment: The animals were divided into normal control group, grape seed extract group and miR-138-5p inhibitor group. The effects of grape seed extract on epiphyseal closure and tibial growth of the tibial plateau in rats were observed. RESULTS AND CONCLUSION: miR-138-5p had a targeting relationship with caspase-3. Compared with the control group, cell proliferation was significantly reduced, apoptosis was significantly increased (P < 0.01), miR-138-5p, Bcl-2 expression was reduced (P < 0.01), and caspase-3 expression was increased (P < 0.01) in the model group. Compared with the mod group, the grape seed extract group showed a significant increase in cell proliferation, a significant decrease in apoptosis (P < 0.01), an increase in miR-138-5p and Bcl-2 expression (P < 0.01) and a decrease in caspase-3 expression (P < 0.01). Compared with the grape seed extract group, the miR-138-5p inhibitor group showed a significant decrease in cell proliferation, a significant increase in apoptosis (P < 0.01), a decrease in miR-138-5p and Bcl-2 expression (P < 0.05 or P < 0.01), and an increase in caspase-3 expression (P < 0.05). Intragastric administration of grape seed extract could delay epiphyseal closure of the tibial plateau and promote tibial bone growth in rats, whereas miR-138-5p inhibitor intervention inhibited the effect of grape seed extract on tibial bone growth in rats. To conclude, grape seed extract can inhibit apoptosis of rat growth plate chondrocytes through regulating the miR-138-5p/caspase-3 pathway, improve epiphyseal closure of rat tibial plateau and promote tibial bone growth. [ABSTRACT FROM AUTHOR]