Effects Of Emodin Nanoparticles On HIV Envelope Protein Gp120 Plus Dideoxycytidine Treatment-associated Neuropathic Pain Mediated By P2X₃ Receptor In Rat DRG

Background and Objective:HIV-associated neuropathic pain is common in human immunodeficiency virus（HIV）infections.HIV infection and antiretroviral therapy（HAART）treatment causes neuropathic pain.The P2X₃ receptor in the dorsal root ganglion（DRG）is involved in the transmission of nociceptive pain and closely related to immune response and inflammation.Emodin has a wide range of pharmacological effects,but its poor water solubility,low bioavailability and other shortcomings limit its clinical application.Thus,the preparation of water-soluble emodin nanoparticles is good for its use.At present,no study for the effects of emodin nanoparticles on P2X₃ receptor-mediated HIV-associated neuropathic pain has been found.This study was aimed to investigate the effects of emodin nanoparticles on the upregulated expression of P2X₃ receptors in rat DRG involved in HIV envelope protein gp120 plus HAART-associated neuropathic pain and its possible mechanism.Methods:1.Nanomaterial carrier（Polymer–Poly（ethylene glycol）methyl ether methacrylate–2-（Diethylamino）ethyl methacrylate–macromolecule,PDAEMA）was prepared through reversible addition-fracture chain transfer polymerization（RAFT）polymerization,which was verified by nuclear magnetic resonance spectroscopy（¹H-NMR）,Fourier transform infrared spectroscopy and transmission electron microscopy（TEM）.Emodin was encapsulated and its release in vitro was studied.2.The effects of PDAEMA-emodin（EMO）on gp120+dd C rats.To test the effects of PDAEMA-EMO,rats were randomly divided into a Control group（Control）,a Sham group（Sham）;a gp120+2’,3’-dideoxycytidine（dd C）neuropathic pain rat group（gp120+dd C）;a gp120+dd C treated with PDAEMA-EMO group（gp120+dd C+PDAEMA-EMO）and a Control treated with PDAEMA-EMO group（Control+PDAEMA-EMO）group.At the 7th,10th,and 13th day after surgery,PDAEMA-EMO dissolved in saline was injected into sublingual vein.The changes of the mechanical withdrawal threshold（MWT）and the paw thermal latency（TWL）in rats were observed by behavioral tests.The effects of PDAEMA-EMO on the expression of the P2X₃ receptor were assessed by real-time PCR and Western blot.The effects of PDAEMA-EMO on the expression of IL-10,TNF-αand phosphorylation of ERK1/2 were assessed by Western blot.Results:PDAEMA was uniform distribution.PDAEMA-EMO was well dispersed in water.The drug loading was（21.6±0.36）%.In vitro release resulte showed that emodin could slowly release from emodin nanoparticles,and the cumulative release rate was 70.1%after 120 h.The influence of PDAEMA-EMO to gp120+dd C in rats:On the 5th or 7th day after surgery,the MWT and TWL in the gp120+dd C and gp120+dd C+PDAEMA-EMO groups were lower than that of the Control rats（p<0.01）.There was no significant difference between the Control group and Sham group（p>0.05）.After injection with PDAEMA-EMO,the MWT and TWL of the gp120+dd C+PDAEMA-EMO group was higher than that of the gp120+dd C group（p<0.01）,while the MWT and TWL of the PDAEMA-EMO group remained lower than that of the Sham group（p<0.05）.Real-time PCR and Western blot testing revealed that the expression levels of P2X₃ m RNA and protein in the gp120+dd C group were higher than that of the Control group（p<0.01）.Compared with the gp120+dd C group,the expression levels of the P2X₃ m RNA and protein in gp120+dd C rats treated with PDAEMA-EMO was significantly decreased（p<0.01）.Western blot results revealed that the protein expression of IL-1β,TNF-αand p-ERK1/2 in the gp120+dd C group was higher than that of the Control group（p<0.01）,and IL-10 expression is lower than Control group.The expression of IL-1β,TNF-αand p-ERK1/2 in the gp120+dd C group treated with PDAEMA-EMO was notably decreased compared with that of the Control group（p<0.01）.Conclusion:Emodin nanoparticles were successfully prepared in the features of good dispersion in water,slow release and stable nature.Emodin nanoparticles decreased the expression levels of TNF-α,IL-1βthe phosphorylation of ERK in gp120+dd C treated rat DRG and increased the expression of IL-10 in gp120+dd C treated rat DRG.Then,emodin nanoparticles reduced mechanical sensitization and thermal sensitization mediated by P2X₃ receptor in gp120+dd C treated rats,and relieved HIV-related neuropathic pain.