[Effect of catgut implantation on macrophage CD68, tumor necrosis factor-α and interleukin-1β in "Zusanli" (ST 36) region of rats].

Objective: To observe the expression of local macrophages and related cytokines tumor necrosis factor-α (TNF-α) and interleukin-1β (IL-1β) after catgut implantation in "Zusanli"(ST 36) in rats, so as to explore its underlying mechanisms in inducing therapeutic effect.

Methods: A total of 110 male SD rats were randomly divided into blank control group (n=10), catgut embedding (CE) group (n=50), and sham CE group (n=50). The CE and sham CE groups were randomly divided into 8 h, 3 d, 7 d, 14 d and 21 d subgroups after the intervention (n=10 in each time point group). Rats of the CE group were uniformly subjected into catgut embedding at ST36 once, and those of the sham CE group received embedding needle puncture at ST36 without catgut retention, and the blank control group was only grasped and fixed without other treatments. Tissues from the ST36 area in each group were collected at the corresponding time points, and the expression of CD68 in macrophages in the acupoint area was detected by immunofluorescence, the contents of TNF-α and IL-1β in the acupoint area were detected by ELISA.

Results: Following catgut embedment at ST36, the contents of TNF-α and IL-1β, and macrophage CD68 expression level began to increase at 8 h, peaked at 3 d, and then gradually decreased at 7, 14, and 21 d, being still higher in the CE group than in the blank control group at 21 d (P<0.05). Compared with the blank control group, the contents of TNF-α and IL-1β, and macrophage CD68 expression were significantly increased at 8 h, and 3, 7, 14 and 21 d in the CE group (P<0.05). Following sham CE at ST36, the content of TNF-α at 8 h and 3 d, IL-1β at 8 h and 3, 7 and 14 d, and expression of CD68 at 8 h were significantly increased in comparison with the blank control group (P<0.05). Comparison between the CE and sham CE groups showed that the contents of IL-1β at 3, 7, 14 and 21 d, and contents of TNF-α，CD68 expression at 8 h, and 3, 7, 14 and 21 d were significantly higher in the CE group than in the sham CE group (P<0.05).

Conclusion: Catgut embedding at ST36 can induce an increase levels of inflammatory cytokines TNF-α, IL-1β and macrophage CD68 in the local microenvironment in rats, which may contribute to its functions in initiating therapeutic effect.