PROJECT SUMMARY Spinal cord injury (SCI) is a devastating event sustained by as many as 1.3 million Americans. While not often appreciated, cardiovascular disease and susceptibility to infection are leading causes of mortality and morbidity in individuals living with SCI. One major reason thought to underlie these issues is SCI-induced dysregulation of the sympathetic nervous system. In this proposal, we will use a clinically-relevant contusion rodent SCI model to test the hypothesis that intracellular sigma peptide (ISP) will promote sufficient sprouting of serotonergic axons onto neurons in the spinal sympathetic circuit below the SCI to normalize sympathetic activity after injury. Furthermore, we hypothesize that administering a combining ISP and inhibition of soluble tumor necrosis factor alpha (sTNFα) with XPro1595 – which target different root causes of sympathetic hyperreflexia after SCI (i.e., interrupted supraspinal input the spinal sympathetic circuit and sTNFα-induced maladaptive plasticity of the spinal sympathetic circuit, respectively) – will have synergistic effects on improving cardiovascular and immune function after SCI.