AVP and brain injury: In contrast, the δ-agonist Leu-enkephalin, β-endorphin, and Arg-vasopressin cause the right limb to flex.12,71,72,74 After brain injury, these neurohormones may be released from the endocrine glands into the bloodstream and induce side-specific effects through their receptors lateralized in the spinal cord or the peripheral afferent and motor nerve terminals.