| Objective Exploring the protective effects and mechanisms of melatonin on D-galactose- induced osteoblast injury and senescence. Methods After adherent culture of mouse calvarial osteoblasts (MC3T3-E1), the control group (CON group), D-galactose group (D-gal group), and melatonin group (MT group) were established. Cell proliferation was assessed using the CCK8 method: different concentrations of D-galactose were applied for 24 hours to construct a cell injury and aging model; different concentrations of melatonin were used for intervention to observe the improvement effect of melatonin on cell proliferation vitality. Cell viability was detected using cell viability staining, apoptosis levels were detected using Annexin V-FITC/7 -AAD flow cytometry, cell aging was detected using β-galactosidase staining, and intracellular ROS levels were detected using DCFH-DA fluorescent probe. Results After treating osteoblasts with different concentrations of D-galactose for 24 hours, the concentration of D-galactose at 40 mg/mL approached the half-inhibitory concentration (IC50). Therefore, this time and concentration were used to establish a cell damage and aging model. The cell proliferation vitality of the CON group, D-gal group, and MT group was (100 ± 0)%, (54.53 ± 3.06)%, and (79.04 ± 6.52)%, respectively. The D-gal group showed a decrease compared to the CON group, while the MT group showed an increase compared to the D-gal group, with both differences being statistically significant (P < 0.001, P < 0.01). The cell survival rates of the CON group, D-gal group, and MT group were (97.78 ± 0.52)%, (84.34 ± 2.61)%, and (96.06 ± 0.41)%, respectively. The D-gal group showed a decrease compared to the CON group, while the MT group showed an increase compared to the D-gal group, with both differences being statistically significant (P < 0.001, P < 0.01). The apoptosis rates of the CON group, D-gal group, and MT group were (5.583 ± 3.12)%, (14.18 ± 2.75)%, and (8.53 ± 1.02)%, respectively. The D-gal group showed an increase compared to the CON group, while the MT group showed a decrease compared to the D-gal group, with both differences being statistically significant (P < 0.05, P < 0.05). The positive expression rates of β-galactosidase in the CON group, D-gal group, and MT group were (6.58 ± 0.57)%, (45.04 ± 4.97)%, and (13.72 ± 1.68)%, respectively. The D-gal group showed an increase compared to the CON group, while the MT group showed a decrease compared to the D-gal group, with both differences being statistically significant (P < 0.001, P < 0.001). The average fluorescence intensity of intracellular ROS detection in the CON group, D-gal group, and MT group was (32.38 ± 1.76)%, (57.59 ± 1.70)%, and (38.06 ± 1.75)%, respectively. The D-gal group showed an increase compared to the CON group, while the MT group showed a decrease compared to the D-gal group. Both differences were statistically significant (P<0.001, P<0.001). Conclusion Melatonin exerts a certain protective effect on osteoblast damage and aging induced by D-galactose, and its mechanism may be associated with the inhibition of cellular oxidative stress levels. |