Effects of moxibustion of "biaoben acupoint combination" on heart rate variability, atrial natriuretic peptide in the model rats of IBS-D complicated with anxiety

Abstract

To compare the effects on the heart rate variability (HRV) and the expression of the atrial natriuretic peptide (ANP) in the model rats of irritable bowel syndrome with predominant diarrhea (IBS-D) rats complicated with anxiety between moxibustion of "biaoben acupoint combination" and that of "conventional acupoint combination". Of 50 healthy SPF female SD rats, aged 3 months, 8 rats were selected randomly as a blank group, and the rest rats were prepared to be the model of IBS-D complicated with anxiety. Twenty-four rats after successfully modeled were randomized into a model group, a conventional acupoint combination group (convention group) and a biaoben acupoint combination group (biaoben group), 8 rats in each one. In the convention group, moxibustion was delivered at "Tianshu" (ST 25), "Zusanli"(ST 36) and "Shangjuxu"(ST 37); and in the biaoben group, moxibustion was applied to "Neiguan" (PC 6), "Zusanli" (ST 36), and "Guanyuan" (CV 4). One session of moxibustion took 20 min, once daily, for 14 days in total. Before and after intervention, the body mass and fecal moisture content were compared in the rats of each group; using abdominal wall withdrawal reflex, the visceral hypersensitivity was evaluated; with elevated plus maze (EPM) and light-dark box (LDB), the anxiety conditions were assessed. After intervention, HRV was compared among groups, the ultrastructure of intestinal mucosa was observed under the transmission electron microscope in the rats of each group, and ANP expression in the myocardial tissue was detected using Western blot method and immunofluorescence. Before the intervention, compared with the blank group, the body mass and visceral pain threshold of rats were reduced in the model group, the convention group and the biaoben group (P<0.05), fecal moisture content and AWR scores (at the dilatation pressure of 40, 60 and 80 mm Hg, 1 mm Hg ≈ 0.133 kPa) were elevated (P<0.05); and time in the open arm, the open arm entry number and the total movement distance (EPM), the time spent in the light compartment, the number of dark to light transitions and the total transition distance (LDB) were decreased (P<0.05). After the intervention, compared with the blank group, in the model group, the body mass, visceral pain threshold, standard diviation of NN intervals (SDNN) and root mean square of successive RR interval differences (RMSSD) were dropped (P<0.05), fecal moisture content, AWR scores (the dilation pressures of 40, 60 and 80 mm Hg), LF/HF and ANP expression were increased (P<0.05), the time in open arm, the open arm entry number and the total movement distance (EPM), the time spent in the light compartment, the number of dark to light transitions and the total transition distance (LDB) were decreased (P<0.05). When compared with the model group, in the convention group and the biaoben group, the body mass, visceral pain threshold, SDNN and RMSSD were increased (P<0.05), fecal moisture content, AWR scores (the dilation pressures of 60 and 80 mm Hg), LF/HF and ANP expression were dropped (P<0.05), the time in open arm, the open arm entry number and the total movement distance (EPM), the time spent in the light compartment, the number of dark to light transitions and the total transition distance (LDB) were increased (P<0.05). In the biaoben group, compared with the convention group, the body mass, visceral pain threshold, SDNN and RMSSD were elevated (P<0.05), fecal moisture content, AWR score (the dilation pressure of 80 mm Hg), LF/HF and ANP expression were decreased (P<0.05), the time in open arm, the open arm entry number and the total movement distance (EPM), the time spent in the light compartment, the number of dark to light transitions and the total transition distance (LDB) were increased (P<0.05). The epithelial cells of the intestinal mucosa showed a normal morphology in the blank group, the tight junction of the cells was disrupted and the junction was loose in the model group; the tight junction was imperfect in the convention group, but it was intact in the biaoben group. Compared with the conventional acupoint combination, moxibustion of biaoben acupoint combination is more effective on the symptoms of IBS-D complicated with anxiety in the model rats. The effect mechanism may be related to attenuating anxiety-like negative emotions, positively regulating HRV, stabilizing IBS-D intestinal mucosal barrier and down-regulating the expression of ANP in myocardium.