Expression Characteristics of Neuropeptide Y and Its Receptors in Psoriatic Chronic Pruritus 

This study aims to describe the expression profiles of the neurotransmitter NPY (neuropeptide Y)and its receptors in the DRG (dorsal root ganglion) and spinal cord of a mouse model of psoriasis. Eight-week-old maleC57BL/6 mice were randomly divided into two groups: the IMQ (imiquimod) modeling group and the blank control group.Behavioral changes and skin inflammation of mice were observed in mice. Skin pathological changes and mast cell infiltration were analyzed using HE staining and toluidine blue staining, respectively. The mRNA expression of NPY in DRG andthe cytokine expression in skin were analyzed by real-time quantitative PCR, and the expression of Npy1r (the gene corresponding to NPY receptor Y1) and Npy2r (the gene corresponding to NPY receptor Y2) were analyzed by RNA in situhybridization. Behavioral changes were observed after intrathecal administration of Y1 antagonist or Y2 antagonist. Thescratching behavior of IMQ modeled mice was significantly increased. Compared with the control group, the skin of micein IMQ model group showed obvious psoriasis inflammatory skin lesions, but the number of mast cells did not change significantly. In skin, the mRNA expression levels of IL-4 and IL-5 in IMQ group did not change significantly compared withcontrol group, while the expression levels of TSLP and IL-33 were increased. In DRG, the mRNA expression level of NPYwas elevated in the IMQ modeling group, and Npy2r was significantly co-expressed with Nppb-positive neurons. In thespinal cord, Npy1r was partially co-expressed with Grp, and Npy1r and Npy2r were co-expressed on some neurons. Intrathecal administration of Y1 antagonist or Y2 antagonist significantly increased scratching behavior of IMQ mice. IMQ caninduce psoriatic lesions in mice and cause pruritus. NPY expression level is increased in DRG, while Npy1r and Npy2r areexpressed in itch neurons. The NPY-Y1/Y2 axis is involved in pruritus in psoriatic model mice.