Effects of Different Local Moxibustion-Like Stimuli at Zusanli (ST36) and Zhongwan (CV12) on Gastric Motility and Its Underlying Receptor Mechanism

Abstract

The aim of this study was to explore the "intensity-response" relationship in local moxibustion-like stimuli- (LMS-) modulated gastric motility and its underlying receptor mechanism. Based on the thermal pain threshold (43°C), 41°C, 43°C, and 45°C LMS were separately applied to ST36 or CV12 for 180 s among ASIC3 knockout (ASIC3-/-) mice, TRPV1 knockout (TRPV1-/-) mice, and their homologous wild-type C57BL/6 mice (n = 8 in each group). Gastric motility was continuously measured by an intrapyloric balloon, and the amplitude, integral, and frequency of gastric motility during LMS were compared with those of initial activities. We found that both 43°C and 45°C LMS at ST36 induced significantly facilitated effect of gastric motility (P < 0.05), while LMS at CV12 induced inhibited effects (P < 0.05). 41°C LMS had no significant impact on gastric motility. Compared with C57BL/6 mice, the facilitatory effect at ST36 and inhibitive effect of LMS at CV12 were decreased significantly in TRPV1-/- mice (P < 0.05; P < 0.01) but not changed markedly in ASIC3-/- mice (P > 0.05). These results suggest that there existed an "intensity-response" relationship between temperature in LMS and its effects on gastric motility. TRPV1 receptor played a crucial role in the LMS-modulated gastric motility.

Figure 1

Changes of gastric motility in response to 41°C LMS among three groups of mice. (a) and (b) displayed representative examples of the alterations of gastric contraction wave induced by 41°C LMS at ST36 or CV12, respectively.

Figure 2

Modulation of gastric motility by 43°C LMS at ST36 among three groups of mice. (a) Representative examples of the alterations of gastric contraction wave induced by 43°C LMS at ST36. (b), (c), and (d) display the pooled data corresponding to the effects of 43°C LMS at ST36 on the amplitude, integral, and frequency of gastric motility in 180 s, respectively. Values before LMS application are presented as 100% and the rates of change are calculated during LMS in each 30 s (^* P < 0.05, compared with the values before LMS application).

Figure 3

Modulation of gastric motility by 45°C LMS at ST36 among three groups of mice. (a) Representative examples of the alterations of gastric contraction wave induced by 45°C LMS at ST36. (b), (c), and (d) display the pooled data corresponding to the effects of 45°C LMS at ST36 on the amplitude, integral, and frequency of gastric motility in 180 s, respectively (^* P < 0.05, ^** P < 0.01, and ^*** P < 0.001, compared with the values before LMS application; ^# P < 0.05, compared with the facilitatory effect of 45°C LMS at ST36 in C57BL/6 mice).

Figure 4

Modulation of gastric motility by 43°C LMS at CV12 among three groups of mice. (a) Representative examples of the alterations of gastric contraction wave induced by 43°C LMS at CV12. (b), (c), and (d) display the pooled data corresponding to the effects of 43°C LMS at CV12 on the amplitude, integral, and frequency of gastric motility in 180 s, respectively (^* P < 0.05, ^** P < 0.01, compared with the values before LMS application).

Figure 5

Modulation of gastric motility by 45°C LMS at CV12 among three groups of mice. (a) Representative examples of the alterations of gastric contraction wave induced by 45°C LMS at CV12. (b), (c), and (d) display the pooled data corresponding to the effects of 45°C LMS at CV12 on the amplitude, integral, and frequency of gastric motility in 180 s, respectively (^* P < 0.05, ^** P < 0.01, and ^*** P < 0.001, compared with the values before LMS application; ^# P < 0.05, ^## P < 0.01, compared with the facilitatory effect of 45°C LMS at CV12 in C57BL/6 mice).