| OBJECTIVES:In this study,we investigated the effect of Shaoyao Gancao Decoction on non-histamine-dependent pruritus transmission in a mouse model of atopic dermatitis(AD)induced by 2,4 dinitrofluorobenzene(DNFB),based on the theory that "itch is the gradient of pain,and pain is the intensity of itch".METHODSIn this experiment,60 SPF grade BALB/c mice,half of which were male and half of which were female,were split into six groups at random: blank group,model group,ketotifen fumarate group,Shaoyao Gancao Decoction ration 1 group(5g of white peony and 10 g of roasted licorice),Shaoyao Gancao Decoction ration 2 group(10g of white peony and 10 g of roasted licorice),Shaoyao Gancao Decoction ration 2group(10g of white peony and 10 g of roasted licorice)and Shaoyao Gancao Decoction ration 3 groups(20g of White Peony,10 g of Roasted Glycyrrhiza glabra),10 in each group.Except for the blank group,each group was induced with DNFB to establish the mouse AD model.100 μL of acetone prepared 0.15% DNFB solution was applied uniformly on the skin of the back of neck of each group on day 1 for sensitization,and 50 μL of the same proportion of acetone prepared 0.15% DNFB solution was applied on the back of neck of each group on days 8,11,14,17 and 20 to stimulate and maintain the The inflammatory response was stimulated and maintained.From day 8 onwards,the blank and model groups were given equal amounts of saline,the ketotifen fumarate group was given ketotifen fumarate 0.33 mg/(kg · d)by gavage,and the Shaoyao Gancao Decoction ratio 1,2 and 3 groups were given peony and licorice soup 3.08/(kg · d),4.11/(kg · d)and 6.16 mg/(kg · d),respectively.Gavage was administered once a day for a fortnight(day 21),with normal diet during the experiment.After the completion of the modelling,the skin lesions on the back of the neck and the number of scratching were observed in each group of mice.At the end of the last intervention(day 21),the mice were executed and fresh skin and DRG were taken from the back of the neck.Immediately afterwards,molecular experiments were performed and the data of each group were analysed:(1)to compare the lesion status and the number of scratching in each group of mice,and to observe the effect of peony and licorice soup on itching;(2)to observe the histomorphological changes of lesions by hematoxylin-eosin(HE)staining;(3)to detect the changes of CXCL10 protein expression in the skin and DRG by ELISA;(4)to detect the changes of CXCL10 protein expression in the skin and DRG by using protein immunoblotting(Western Blot,WB)to detect the expression of CXCR3,Mrpgpr A3 and TRPV1 in mouse skin and DRG;(5)RT-PCR to detect the expression of CXCR3,Mrpgpr A3 and TRPV1 in mouse skin and DRG;(6)Immunofluorescence to detect the distribution of TRPV1 in mouse skin.RESULTSThe model group of rodents displayed AD-like skin lesions after receiving DNFB,including red corn-like rash,patchy fractured makeup erythema,edema,oozing,rough and thickened skin,as well as an increase in scratching(P < 0.05);the Shaoyao Gancao Decoction1,2 and 3 groups showed relief of the skin lesions on the back of the neck compared with the model group,and the number of scratching was significantly reduced(P < 0.05).2.Histopathology showed that the mice in the model group showed hyperkeratosis,marked thickening of the spinous layer and a significant infiltration of lymphocytes in the dermis,corresponding with the pathological features of AD lesions;Mice in the Shaoyao Gancao Decoction 1,2,and3 groups displayed a slight keratinization,a slight thickening of the epidermis,and a rise in lymphocytes;Shaoyao Gancao Decoction 1,2,and 3 sets of mice had lower levels of CXCL10 in their skin and DRG than the model mice did(P < 0.05).4.In the skin,compared with the model group,mice in Shaoyao Gancao Decoction 1,2 and 3groups showed lower expression of CXCR3,Mrpgpr A3 and m TRPV1 protein expression and m RNA expression were significantly decreased in the DRG(P < 0.05).5.In the DRG,gene expression of CXCR3 was decreased in the Shaoyao Gancao Decoction group of mice compared to the model group(P < 0.05),and Mrpgpr A3 and TRPV1 protein and gene expression were increased and decreased in the Shaoyao Gancao Decoction group of mice,without a difference that is statistically meaningful(P > 0.05).CONCLUSIONShaoyao Gancao Decoction improved the manifestation of DNFB-induced ADlike skin lesions in mice,reduced pruritus,inflammatory edema and exudation,decreased inflammatory cell infiltration,and decreased CXCL10,CXCR3,Mrgpr A3,TRPV1 expression,which may be one of the mechanisms of non-histaminedependent pruritic transmission in AD mice treated with Shaoyao Gancao Decoction,providing ideas for Shaoyao Gancao Decoction to treat pruritus. |
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