BPS2026 – Neural pathways in the bone: Rethinking osteocyte mechanotransduction

Bone is a highly innervated and mechanically regulated tissue. Osteocytes, the principal mechanosensory cells in the bone, exist in close proximity to cholinergic nerve fibers, suggesting a potential role for neural regulation of skeletal adaptation. Previous studies have shown that cholinergic signaling contributes to the bone’s adaptation to mechanical loading, but the underlying cellular mechanisms remain poorly defined. Our group has recently demonstrated that conditional deletion of cholinergic receptor components in osteocytes leads to altered bone morphology and sexually dimorphic differences in osteocyte responses to mechanical load, underscoring the complexity of this signaling pathway. In the present work, we extend these findings by leveraging local pharmacological modulation of acetylcholine (ACh) signaling in vivo during intravital imaging, while applying conditional knockout models for tissue-clearing and lightsheet imaging to define structural aspects of bone innervation. Our results reveal that osteocyte calcium signaling responses to mechanical strain are tuned by cholinergic signaling, highlighting a direct neurotransmitter influence on how bone cells interpret mechanical cues. Whole-mount 3D imaging of cleared bones further establishes that cholinergic fibers are broadly distributed throughout the cortical and trabecular compartments, supporting the idea that nerves are positioned to regulate osteocyte function. Viewed together, these studies support a new paradigm in which neural inputs act alongside mechanical forces to shape osteocyte biology and skeletal adaptation. By combining intravital multiphoton microscopy, lightsheet imaging of cleared bone, and osteocyte-targeted genetic models, our work defines a novel bone-neural signaling axis that expands the mechanobiology framework. This advance not only reframes how we understand the integration of mechanical and neural cues in skeletal tissue but also suggests new therapeutic opportunities for targeting neuro-osteocyte interactions in age-related bone loss and osteoporosis.