Surprisingly, old individuals with a traumatic brain injury see – if they survive – a substantial callus formation of their fractures. Similar effects are reported for some forms of traumatic spinal cord injuries. Overall, energy distribution, alpha-adrenergic signalling and bone regeneration seem to be coupled but the details of this coupling remain so far unknown. Tsitsilonis and Pumberger will analyse this paradoxical phenomenon. Previous data link this effect to an increased alpha-adrenergic signalling through an activated fat metabolism. In order to understand the strong neural component, the alpha-adrenergic component on bone formation during polytrauma injuries will be analysed. The neuroosteological aspect of this project is supported by metabolic and immunological aspects to enlarge the understanding of regenerative processes.