Water-Soluble Polymer Assists N-Methyl-D-Aspartic Acid Receptor 2B siRNA Delivery to Relieve Chronic Inflammatory Pain In Vitro and In Vivo

Abstract

We constructed a water-soluble lipopolymer (WSLP) as a nonviral gene carrier to deliver siRNA targeting NR2B. The cytotoxicity and serum stability of WSLP loaded with siRNA were evaluated, and the knockdown efficiency of WSLP/NR2B-siRNA in PC12 cells was examined. The results showed that WSLP could protect the loading siRNAs from enzymatic degradation in serum and exhibit low cytotoxicity to cells. After transfection, WSLP/NR2B-siRNA complexes reduced the NR2B transcriptional level by 50% and protein level by 55% compared to control siRNA. Moreover, 3 days after intrathecal injection of WSLP/NR2B-siRNA complexes into rats, the NR2B protein expression decreased significantly to 58%, compared to control treatment (p < 0.01). Injection of WSLP with scrambled siRNA or of polyethylenimine (PEI) with NR2B-siRNA did not show this inhibitory effect. Additionally, injection of WSLP/NR2B-siRNA complexes significantly relieved inflammatory pain in rats at 3, 4, and 5 days with reduced MWT and decreased TWL scores, while injection of WSLP with scrambled siRNA or of PEI with NR2B-siRNA did not. These results demonstrated that WSLP can efficiently deliver siRNA targeting NR2B to PC12 cells and relieve pain in rats with chronic inflammatory pain.

NFAT5 Deficiency Alleviates Formalin-Induced Inflammatory Pain Through mTOR

“…n -methyl-D-aspartate receptor (NMDAR), a glutamate receptor, plays a pivotal role in pain by mediating excitation [ 36 ]. In the formalin-induced inflammatory pain model, NR2B, which is a subunit of NMDAR, cooperates with MAPKs to influence pain generation [ 6 , 15 ]. Therefore, we examined the activation of NR2B in response to formalin injection.…”

“…For example, inhibition of p38 MAPK phosphorylation via pre-emptive treatment with endomorphins attenuates inflammatory pain by reducing the production of inflammatory cytokines in dorsal root ganglion (DRG) neurons [ 14 ]. Moreover, silencing of Nr2b relieves pain in rats with chronic inflammatory pain [ 15 ]. Formalin injection results in spontaneous pain behaviors and increases the expression of the mu-opioid receptor, c-Fos, and phosphorylated extracellular signal-regulated kinase (p-ERK1/2), which participates in MAPK signaling in the ipsilateral trigeminal ganglion (TG) [ 16 ].…”