Objective: To discuss mechanism of moxibustion(thermal stimulation) effect and best moxibustion stimulus parameter.Methods: Experiments were performed on 48 male Sprague-Dawley rats. Unit discharges from individual single neuron were recorded extracellularly with glass-microelectrode in Subnucleus Reticularis Dorsalis(SRD). Visceral-intrusive stimulation is done by colorectal distension. Thermal stimulation with different temperature(40°C, 42°C, 44°C, 46°C, 48°C, 50°C, 52°C) and different stimulus area(diameter of circle : 1.0 cm, 1.5 cm, 2.0 cm, 2.5 cm, 3.0 cm, 3.5 cm, 4.0 cm) was applied around RN12 during nociceptive colorectal distension.Results: SRD neurons could be activated by visceral stimulation within noxious range. Under low temperature of stimulus, especially under45°C of pain threshold to ordinary people, visceral nociceptive afferent facilitated thermal stimulus from the body surface. While after thermal stimulation reached a harmful degree, the thermal stimulus will inhibit visceral nociceptive afferent. Moreover, statistics show that the higher the temperature is, the smaller the size of stimulation area is needed, and they correlate with each other negatively.Conclusion: Visceral nociception could be inhibited by somatic thermal stimulation with specific parameter at medulla level. According to our finding, best thermal stimulation temperature is around 48°C and the best size of stimulation area is around 3.14-7.07 cm2(with 2.0-3.0 cm diameter).
Objective： To investigate the biochemical characteristic of the neurons associated Zusanli （ST 36） in the rat by using Alexa Fluor 594 conjugated cholera toxin subunit B （AF594-CTB） neural tracing and calcitonin gene-related peptide （CGRP） fluorescent immunohistochemical techniques. Methods： Four male Sprague Dawley rats were injected with AF594-CTB into the corresponding area of the Zusanli in the human body. After 3 surviving days, the rat＇s spinal cord and dorsal root ganglia （DRGs） at lumbar segments were dissected following perfusion with 4% paraformaldehyde, cut into sections, and then stained with CGRP- fluorescent immunohistochemical method. Results： AF594-CTB labeled sensory neurons were detected in the L3-L6 DRGs with high concentration in L4 DRG, and the labeled motor neurons located in the dorsolateral and intermediate regions of lamina IX from L3-L5 segments with high concentration at L4. Meanwhile, CGRP- positive neural labeling distributed symmetrically on both sides of DRGs, anterior and dorsal horns of spinal cord. In the AF594-CTB labeled neurons, 37% sensory neurons and 100% motor neurons expressed CGRP- positive. Conclusion： These findings present the morphological evidence to demonstrate that the sensory and motor neurons associated Zusanli in the rat distributed with segmental and regional patterns, and contained CGRP-expression.
