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

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.