IADR Abstract Archives
Botulinum toxin differentially affects male/female masticatory system in mice
Objectives: Botulinum toxin type A (BoNTA) injection in masticatory muscles is an off-label treatment widely used for aesthetic and clinical interventions of the masticatory system. We have demonstrated that BoNTA-unilateral injection in mice masseter muscle evokes muscle atrophy and mandibular condyle bone loss. All our previous work has been carried out in adult male mice. However, patients undergoing BoNTA injections are primarily women. Considering that females are more sensitive to stimuli evoking musculoskeletal damage, the current study aimed to evaluate and compare the BoNTA-evoked musculoskeletal injury in the masticatory system of male/female adult mice.
Methods: Male/Female 9 weeks-old mice (18 of each) were injected with 0.2U BoNTA and saline solution in the right and left masseter muscle, respectively. Groups of 6 males/females were euthanized at 2d, 7d, or 14d after the intervention. Masseter muscles were dissected and processed for mRNA detection of atrophy/regeneration markers (Atrogin, Murph, Myogenin) by qPCR. Mandibles were stored in formalin and scanned by micro-computed tomography (micro-CT, 5.8 μm voxel; John Nyakatura lab, University of Humboldt, Berlin). 3D-reconstructions and microstructure analysis were performed with DRAGONFLY (Object Research Systems, Canada).
Results: In masseter muscles, BoNTA evoked a significant increase in the atrophy markers Atrogin and Murf at 2-7d, both in males and females. However, the induction of the muscle regeneration marker Myogenin was greater in BoNTA-injected muscles of males than in females. On the other hand, in the mandibular condyle, BoNTA evoked a similar reduction in the parameters of Bone Volume and Trabecular Thickness in males/females, 7-14d after the intervention. However, BoNTA prompted an earlier and higher reduction in Bone Volume Fraction and increased Trabecular Space in females than in males.
Conclusions: These results suggest a higher susceptibility of females to musculoskeletal damage of the masticatory system evoked by BoNTA, which should be taken into account when considering its clinical use.
Methods: Male/Female 9 weeks-old mice (18 of each) were injected with 0.2U BoNTA and saline solution in the right and left masseter muscle, respectively. Groups of 6 males/females were euthanized at 2d, 7d, or 14d after the intervention. Masseter muscles were dissected and processed for mRNA detection of atrophy/regeneration markers (Atrogin, Murph, Myogenin) by qPCR. Mandibles were stored in formalin and scanned by micro-computed tomography (micro-CT, 5.8 μm voxel; John Nyakatura lab, University of Humboldt, Berlin). 3D-reconstructions and microstructure analysis were performed with DRAGONFLY (Object Research Systems, Canada).
Results: In masseter muscles, BoNTA evoked a significant increase in the atrophy markers Atrogin and Murf at 2-7d, both in males and females. However, the induction of the muscle regeneration marker Myogenin was greater in BoNTA-injected muscles of males than in females. On the other hand, in the mandibular condyle, BoNTA evoked a similar reduction in the parameters of Bone Volume and Trabecular Thickness in males/females, 7-14d after the intervention. However, BoNTA prompted an earlier and higher reduction in Bone Volume Fraction and increased Trabecular Space in females than in males.
Conclusions: These results suggest a higher susceptibility of females to musculoskeletal damage of the masticatory system evoked by BoNTA, which should be taken into account when considering its clinical use.