Effects of spironolactone on cytotoxic damage in osteoblasts

Chronic hyperglycemia in diabetes elevates oxidative stress, damaging pancreatic β-cells and worsening complications. Oxidative stress also disrupts osteoblast function, suppresses their maturation and triggers apoptosis, thereby contributing to bone fragility. Spironolactone, an aldosterone receptor antagonist prescribed for the treatment of hypertension and heart failure, has potential protective effects on skeletal health. The present study examined whether spironolactone could protect osteoblasts from damage and restore their differentiation under oxidative conditions caused by 2-deoxy-D-ribose (dRib). MC3T3-E1 pre-osteoblastic cells were incubated with spironolactone (0-100 µM) and 15 mM dRib. Cell toxicity (through lactate dehydrogenase release), markers of differentiation (collagen content, alkaline phosphatase activity and mineral deposition), inflammatory cytokine levels (TNF-α and IL-6), reactive oxygen species (ROS), mitochondrial superoxide levels, endoplasmic reticulum (ER) stress markers (activating transcription factor 6 and inositol-requiring enzyme 1), mitochondrial integrity (mitochondrial membrane potential and ATP levels), glyoxalase I activity and reduced glutathione (GSH) levels were analyzed by ELISA. Pretreatment with spironolactone reduced dRib-induced toxicity and improved differentiation markers in MC3T3-E1 cells. It also lowered the elevated cytokine levels, ROS production, mitochondrial oxidative burden and ER stress responses caused by dRib. Furthermore, spironolactone preserved mitochondrial performance and enhanced antioxidant defenses by increasing GSH levels and glyoxalase I activity, thereby promoting the detoxification of harmful byproducts. These findings suggested that spironolactone may protect osteoblasts by mitigating oxidative and inflammatory stress, stabilizing mitochondrial function and enhancing differentiation. Overall, this highlights the possible benefits of spironolactone in the management of diabetes-related bone fragility.