A pain killer without analgesic tolerance designed by co-targeting PSD-95-nNOS interaction and α2-containning GABAARs

Theranostics. 2021 Apr 3;11(12):5970-5985. doi: 10.7150/thno.58364. eCollection 2021.

Abstract

Overactivation of N-methyl-D-aspartate receptor (NMDAR) in the spinal cord dorsal horn (SDH) in the setting of injury represents a key mechanism of neuropathic pain. However, directly blocking NMDAR or its downstream signaling, interaction between postsynaptic density-95 (PSD-95) and neuronal nitric oxide synthase (nNOS), causes analgesic tolerance, mainly due to GABAergic disinhibition. The aim of this study is to explore the possibility of preventing analgesic tolerance through co-targeting NMDAR downstream signaling and γ-aminobutyric acid type A receptors (GABAARs). Methods: Mechanical/thermal hyperalgesia were quantified to assess analgesic effects. Miniature postsynaptic currents were tested by patch-clamp recording to evaluate synaptic transmission in the SDH. GABA-evoked currents were tested on HEK293 cells expressing different subtypes of recombinant GABAARs to assess the selectivity of (+)-borneol and ZL006-05. The expression of α2 and α3 subunits of GABAARs and BDNF, and nNOS-PSD-95 complex levels were analyzed by western blotting and coimmunoprecipitation respectively. Open field test, rotarod test and Morris water maze task were conducted to evaluate the side-effect of ZL006-05. Results: (+)-Borneol selectively potentiated α2- and α3-containing GABAARs and prevented the disinhibition of laminae I excitatory neurons in the SDH and analgesic tolerance caused by chronic use of ZL006, a nNOS-PSD-95 blocker. A dual-target compound ZL006-05 produced by linking ZL006 and (+)-borneol through an ester bond blocked nNOS-PSD-95 interaction and potentiated α2-containing GABAAR selectively. Chronic use of ZL006-05 did not produce analgesic tolerance and unwanted side effects. Conclusion: By targeting nNOS-PSD-95 interaction and α2-containing GABAAR simultaneously, chronic use of ZL006-05 can avoid analgesic tolerance and unwanted side effects. Therefore, we offer a novel candidate drug without analgesic tolerance for treating neuropathic pain.

Keywords: GABAA receptors; analgesic tolerance; central sensitization; excitatory/inhibitory synaptic transmission; neuropathic pain.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Aminosalicylic Acids / pharmacology
  • Analgesics / pharmacology*
  • Animals
  • Benzylamines / pharmacology
  • Cell Line
  • Disks Large Homolog 4 Protein / metabolism*
  • HEK293 Cells
  • Humans
  • Male
  • Membrane Proteins / metabolism
  • Mice
  • Mice, Inbred C57BL
  • Neuralgia / drug therapy*
  • Neuralgia / metabolism
  • Neurons / drug effects
  • Neurons / metabolism
  • Neuroprotective Agents / pharmacology
  • Nitric Oxide Synthase Type I / metabolism*
  • Pain Management / methods
  • Rats
  • Rats, Sprague-Dawley
  • Receptors, GABA-A / metabolism*
  • Signal Transduction / drug effects
  • Spinal Cord / drug effects
  • Spinal Cord / metabolism
  • gamma-Aminobutyric Acid / metabolism

Substances

  • Aminosalicylic Acids
  • Analgesics
  • Benzylamines
  • Disks Large Homolog 4 Protein
  • Dlg4 protein, mouse
  • Membrane Proteins
  • Neuroprotective Agents
  • Receptors, GABA-A
  • ZL006 compound
  • gamma-Aminobutyric Acid
  • Nitric Oxide Synthase Type I
  • Nos1 protein, mouse