Effects of catgut embedding and PGLA embedding at "Zusanli" (ST 36) on skin mast cells, substance P and histamine in healthy rats / 中国针灸

OBJECTIVE@#To observe the effects of catgut embedding and polyglycolic acid/poly-lactic acid (PGLA) embedding at "Zusanli" (ST 36) on the activation of local skin mast cells (MC), and expression of substance P (SP) and histamine (HA), and to explore the mechanism of the temporal stimulation effect of acupoint catgut embedding and provide a foundation for further research on the initiation mechanism of acupoint catgut embedding.@*METHODS@#One hundred and sixty male SPF-grade SD rats were randomly divided into a blank group (10 rats), a sham-embedding group (50 rats), a catgut group (50 rats), and a PGLA group (50 rats). Each intervention group was further randomly divided into five subgroups according to the time points after intervention: 8 hours, 3 days, 7 days, 14 days, and 21 days, with 10 rats in each subgroup. One-time sham-embedding, catgut embedding and PGLA embedding was given at left "Zusanli" (ST 36) in each intervention group, respectively. The skin and subcutaneous connective tissue of the left "Zusanli" (ST 36) were collected at the corresponding time points after intervention, except for the blank group (only one day before intervention). Toluidine blue staining was used to detect MC count and degranulation, and immunohistochemical staining was used to detect the expression of SP and HA positive cells.@*RESULTS@#There was no significant difference in MC count between the subgroups of each intervention group and the blank group (P>0.05). There was no significant difference in MC count between the subgroups of the catgut group and the PGLA group (P>0.05). The MC count in the 8-hour subgroup of PGLA group was higher than that in the 8-hour subgroup of catgut group (P<0.05), while the MC count in the 21-day subgroup of PGLA group was lower than that in the 21-day subgroup of catgut group (P<0.05). Compared with the blank group, the degranulation rates of MC were increased in the 8-hour and 3-day subgroups of sham-embedding group, 8-hour, 3-day, and 7-day subgroups of catgut group, and 8-hour, 3-day, 7-day, and 14-day subgroups of PGLA group (P<0.01, P<0.05, P<0.001). There was no significant difference in the degranulation rate of MC between the subgroups of the catgut group and the PGLA group (P>0.05), and no significant difference in the degranulation rate of MC between the two embedding groups at the same time point (P>0.05). Compared with the blank group, the expression of SP positive cells was increased in the 8-hour subgroup of sham-embedding group, 8-hour, 3-day, 7-day, and 14-day subgroups of catgut group, and 3-day, 7-day, and 14-day subgroups of PGLA group (P<0.001, P<0.05). The expression of SP positive cells in the 7-day subgroup of catgut group was higher than that in the 8-hour subgroup of catgut group (P<0.05), while the expression of SP positive cells in the 14-day subgroup of catgut group was lower than that in the 7-day subgroup of catgut group (P<0.001). The expression of SP positive cells in the 7-day subgroup of PGLA group was higher than that in the 3-day subgroup of PGLA group (P<0.05), while the expression of SP positive cells in the 14-day subgroup of PGLA group was lower than that in the 7-day subgroup of PGLA group (P<0.01). There was no significant difference in the expression of SP positive cells between the subgroups of the two embedding groups at the same time point (P>0.05). Compared with the blank group, the expression of HA positive cells was increased in the 8-hour, 3-day subgroups of sham-embedding group, 8-hour, 3-day, 7-day, and 14-day subgroups of catgut group, and 8-hour, 3-day, 7-day, 14-day, and 21-day subgroups of PGLA group (P<0.001, P<0.01, P<0.05). The expression of HA positive cells in the 14-day subgroup of catgut group was lower than that in the 7-day subgroup of catgut group (P<0.05), while the expression of HA positive cells in the 3-day subgroup of PGLA group was higher than that in the 8-hour subgroup of PGLA group (P<0.05), and the expression of HA positive cells in the 14-day subgroup of PGLA group was lower than that in the 7-day subgroup of PGLA group (P<0.05). The expression of HA positive cells in the 3-day subgroup of PGLA group was higher than that in the 3-day subgroup of catgut group (P<0.05).@*CONCLUSION@#Catgut and PGLA embedding at "Zusanli" (ST 36) in healthy rats could induce changes in local skin MC, SP, and HA, which may be one of the mechanisms of the temporal stimulation effect after acupoint embedding. There are certain differences between different suture materials. A moderate inflammatory response in the acupoint area, mediated by MC and involving SP and HA, may be one of the initiating factors for the effect of acupoint catgut embedding.

Sensory and sympathetic nerves are involved in the changes of skin temperature, blood infusion and inflammatory cytokines of cutaneous tissue in the sensitized area of colitis rats / 中国针灸

OBJECTIVE@#To investigate the changes of skin temperature, blood infusion and inflammatory cytokines of cutaneous tissue in the sensitized area of colitis model rats, as well as the relationship between sensory and sympathetic nerves and the formation of sensitized area, and to initially reveal the partial physical-chemical characteristics of the sensitized area in the colitis model rats.@*METHODS@#Thirty-five male SD rats were randomly divided into a control group (n=10), a model group (n=18) and a guanethidine group (n=7). 5% dextran sulfate sodium (DSS) was adopted for 6-day free drinking to establish colitis model in the model group and the guanethidine group. On day 6 and 7, in the guanethidine group, guanethidine solution (30 mg/kg) was injected intraperitoneally for sympathetic block. On day 7, after injection of evans blue (EB) solution, the EB extravasation areas on the body surface were observed to investigate the distribution and physical-chemical characteristics of the sensitized area. The control area was set up, 0.5 cm away from the sensitized area, and with the same nerve segment innervation. Disease activity index (DAI) score of rats was compared between the normal group and the model group, and the morphological changes in the colon tissue were investigated with HE method. Using infrared thermal imaging technology and laser speckle flow imaging technology, skin temperature and blood infusion were determined in the sensitized area and the control area of the rats in the model group. Immunofluorescence technique was adopted to observe the expression levels of the positive nerve fibers of substance P (SP), calcitonin gene-related peptide (CGRP) and tyrosine hydroxylase (TH), and the correlation with blood vessels; as well as the expression levels of SP positive nerve fibers/tryptase+ mast cells, and tryptase+ mast cells/5-hydroxytryptamine (5-HT) in skin tissue in the sensitized area and the control area of the rats in the model group. MSD multi-level factorial method and ELISA were applied to determine the contents of pro-inflammatory and anti-inflammatory cytokines (e.g. TNF-α, IL-1β, IL-6, IL-4 and IL-10) and anti-inflammatory substance corticosterone (CORT).@*RESULTS@#Sensitization occurred at the T12-S1 segments of the colitis model rats, especially at L2-L5 segments. Compared with the normal group, DAI score was increased in the rats of the model group (P<0.05), and the colonic mucosal damage was obvious, with the epithelial cells disordered, even disappeared, crypt destructed, submucosal edema and a large number of inflammatory cells infiltrated. In comparison with the control area, the skin temperature and blood infusion were increased in the sensitized area of the model group (P<0.05, P<0.01); as well as the expression levels of the positive nerve fibers of SP, CGRP and TH of skin tissue (P<0.05), which was specially distributed in peripheral vessels, the expression levels of SP positive nerve fibers/tryptase+ mast cells, and tryptase+ mast cells/5-HT of the skin tissue were all expanded (P<0.05) in the sensitized area of the model group. Compared with the model group, the number of sensitized areas was reduced in the guanethidine group (P<0.05). In comparison with the control area of the model group, in the sensitized area, the contents of pro-inflammatory cytokines, e.g. TNF-α, IL-1β and IL-6, and the anti-inflammatory substance CORT of skin tissue were all increased (P<0.05); and the contents of IL-6 and TNF-α were negatively correlated with CORT (P<0.05).@*CONCLUSION@#The sensitized areas on the body surface of colitis rats are mainly distributed in the L2-L5 segments. Sensory and sympathetic nerves are involved in the acupoint sensitization, and the sensitized areas may have the dynamic changes in pro-inflammatory and anti-inflammatory substances.