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

• Published in: Theranostics 2021, Vol.11 (12), p.5970-5985
• Main Authors: Li, Jun, Zhang, Lin, Xu, Chu, Shen, Ying-Ying, Lin, Yu-Hui, Zhang, Yu, Wu, Hai-Yin, Chang, Lei, Zhang, Ying-Dong, Chen, Rong, Zhang, Zheng-Ping, Luo, Chun-Xia, Li, Fei, Zhu, Dong-Ya
• Format: Article
• Language: English
• ISSN: 1838-7640; 1838-7640
• DOI: 10.7150/thno.58364

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 (GABA Rs). 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 GABA Rs to assess the selectivity of (+)-borneol and ZL006-05. The expression of α2 and α3 subunits of GABA Rs 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. (+)-Borneol selectively potentiated α2- and α3-containing GABA Rs 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 GABA R selectively. Chronic use of ZL006-05 did not produce analgesic tolerance and unwanted side effects. By targeting nNOS-PSD-95 interaction and α2-containing GABA R 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.