Effect of different concentrations of moxa smoke exposure on nasal mucosal injury and expression of serum IL-1, IL-6 and TNF-α in rats

Abstract

To observe the effect of long-term moxa smoke exposure of different concentrations on olfactory function in rats, and provide experimental basis of safety study of moxa smoke produced by moxibustion. Forty SD rats were randomly divided into a normal control group, a low-concentration moxa smoke group, a moderate-concentration moxa smoke group and a high-concentration moxa smoke group, 10 rats in each one. The rats in the moxa smoke groups were put into three plexiglass moxibustion boxes with different moxa smoke concentrations, 4 hours per times, twice a day for 90 days. The general state of rats was evaluated before and during the experiment. After the intervention, the olfactory function was evaluated by two-bottle experiment (TBE); the morphology of nasal mucosa was observed by HE staining; the apoptosis of olfactory epithelial cells in nasal mucosa was detected by TUNEL method; the serum levels of interleukin-1 (IL-1), interleukin-6 (IL-6) and tumor necrosis factor-α (TNF-α) were detected by ELISA method. In the late stage of moxa smoke exposure (45-90 days into intervention), the behavioral activity of rats in the moderate-concentration moxa smoke group and the high-concentration moxa smoke group was weaker than that in the normal control group, and their response to stimulation was strong, and their mental state was worse. After intervention, the drinking rate of vinegar-water mixture in the moderate-concentration moxa smoke group and the high-concentration moxa smoke group was higher than that in the normal control group and the low-concentration moxa smoke group (P<0.01). The hierarchical structure of nasal mucosa in the moderate-concentration moxa smoke group and the high-concentration moxa smoke group was unclear, disordered, necrotic and inflammatory cell infiltration was serious; the number of apoptotic cells in olfactory epithelium of nasal mucosa in the moderate-concentration moxa smoke group and the high-concentration moxa smoke group was more than that in the normal control group and the low-concentration moxa smoke group (P<0.01), that in the high-concentration moxa smoke group was more than the moderate-concentration group (P<0.01). The serum levels of IL-1, IL-6 and TNF-α in the low-concentration moxa smoke group, the moderate-concentration moxa smoke group and the high-concentration moxa smoke group were higher than the normal control group (P<0.01), and those in the moderate-concentration moxa smoke group and the high-concentration moxa smoke group were higher than the low-concentration moxa smoke group (P<0.01), and those in the high-concentration moxa smoke group were higher than moderate-concentration moxa smoke group (P<0.01). The long-term exposure to low, moderate and high concentrations of moxa smoke could cause pathological changes in nasal mucosa and increase the serum levels of IL-1, IL-6 and TNF-α; the moderate and high concentrations of moxa smoke exposure could cause a series of damage to olfactory function and reduce olfactory sensitivity in rats.