|Title||Blockade of non-opioid excitatory effects of spinal dynorphin A at bradykinin receptors.|
|Publication Type||Journal Article|
|Year of Publication||2015|
|Authors||Lee YSun, Hall SM, Ramos-Colon C, Remesic M, Rankin D, Vanderah TW, Porreca F, Lai J, Hruby VJ|
|Journal||Receptors Clin Investig|
Dynorphin A (Dyn A) is an endogenous opioid ligand that possesses neuroinhibitory (antinociceptive) effects via μ, δ, and κ opioid receptors. However, under chronic pain conditions, up-regulated spinal Dyn A can also interact with bradykinin receptors (BRs) to promote hyperalgesia through a neuroexcitatory(pronociceptive) effect. These excitatory effects cannot be blocked by an opioid antagonist, and thus are non-opioid in nature. On the basis of the structural dissimilarity between Dyn A and endogenous BR ligands, bradykinin(BK) and kallidin (KD), Dyn A's interaction with BRs could not be predicted, and provided an opportunity to identify a novel potential neuroexcitatory target. Systematic structure-activity relationship (SAR) studies discovered a minimum pharmacophore of Dyn A, [des-Arg(7)]-Dyn A-(4-11) LYS1044 for antagonist activity at the BRs, along with insights into the key structural features for BRs recognition, i.e., amphipathicity. The des-Tyr fragment of dynorphin does not bind to opioid receptors. Intrathecal administration of des-Tyr dynorphin produces hyperalgesia reminiscent of behaviors seen in peripheral n europathic pain models and at higher doses, neurotoxicity. Our lead ligand LYS1044 negatively modulated Dyn A-(2-13)-induced neuroexcitatory effects in naïve animals and blocked mechanical hypersensitivity and thermal hyperalgesia in a dose-dependent manner in animals with experimental neuropathic pain. Based on these results, ligand LYS1044 might prevent abnormal pain states by blocking the neuroexcitatory effects of increased levels of Dyn A that are seen in experimental models of neuropathic pain and that likely promote excitation mediated by BRs in the spinal cord.
|Alternate Journal||Receptors Clin Investig|
|PubMed Central ID||PMC4515361|
|Grant List||P01 DA006284 / DA / NIDA NIH HHS / United States |
R01 DA013449 / DA / NIDA NIH HHS / United States
Blockade of non-opioid excitatory effects of spinal dynorphin A at bradykinin receptors.
Faculty Member Reference:
Frank Porreca, PhD
Todd Vanderah, PhD