Pantoprazole, a proton pump inhibitor, does not prevent botulinum toxin induced disuse osteopenia in mice

OBJECTIVES: Pantoprazole is a proton pump inhibitor that has been shown to inhibit bone resorption. The aim of the study was to investigate whether pantoprazole can prevent development of botulinum toxin (BTX)-induced disuse osteopenia in mice. METHODS: Forty-eight 16-week-old female C57BL/6J mice were randomized into 4 groups (n=12): Base, Ctrl, BTX, and BTX+Pan. The Base group was euthanized at study start. The BTX and BTX+Pan groups were immobilized by injections with BTX in one hind limb. The BTX+Pan group was injected i.p. daily with 100 mg pantoprazole per kg bodyweight. The mice were euthanized after 3 weeks of treatment. The skeletal status was investigated by DEXA, μCT, mechanical testing, dynamic bone histomorphometry, and RT-qPCR. The bone sites investigated were tibia, femur, L5 vertebra, and humerus. RESULTS: Injections of BTX induced a pronounced and significant loss of bone density, microstructure, and strength in the immobilized hind limb. Furthermore, the localized intramuscular injections of BTX lead to a slight loss of bone and bone strength at the L5 vertebra and humerus. Treatment with pantoprazole did not have any bone protective or deleterious effects. CONCLUSION: Pantoprazole was unable to prevent the development of BTX induced disuse osteopenia in skeletally mature female C57BL/6J mice.