Objective: To observe the synchronism difference of brain region activities in response to acupuncture stimulation of Zusanli (ST 36) in healthy volunteer subjects with different acupuncture analgesia sensitivity, so as to study the central factors influencing acupuncture intervention outcomes.
Methods: Forty-five healthy volunteer subjects with different constitutions (different sensitivities in response to needling stimulation) were divided into insensitive group, normal group and sensitive group (n = 15). The pressure pain threshold (PPT) of the Zusanli (ST 36) region before and after acupuncture stimulation of ST36 was assessed using visual analog scale (VAS). Two weeks later after acupuncture stimulation of ST 36, resting-state fMRI images were acquired by using a nuclear magnetic resonance imaging system and analyzed by using DPARSFV 2.1 software package, software SPM 8 and REST 1.7. The cerebral regional homogeneity (ReHo) of the subjects was then calculated by Resting-State fMRI Data Analysis Toolkit (REST).
Results: Compared with pre-acupuncture, PPT levels of the normal and sensitive groups were significantly increased after acupuncture of ST 36 (P < 0.05), and that of the insensitive group had no significant change (P > 0.05). Following acupuncture stimulation of ST 36, the insensitive group only showed a significant decreased ReHo in the left fusiform gyrus, left inferior temporal gyrus, bilateral postcentral gyrus, and left anterior central gyrus. In the normal group, a significantly increased ReHo was found in left brainstem, the right cerebellum posterior lobe, right parahippocampa gyrus, right fusiform gyrus, left angular gyrus, temporal lobe and the left frontal lobe; and a significantly decreased ReHo in the occipital lobes and the right superior temporal gyrus after acupuncture stimulation of ST 36. In the sensitive group, a markedly increased ReHo was found in the left brainstem, bilateral cerebellum posterior lobes, left inferior temporal gyrus, basal ganglia, the left insular lobe, anterior cingutate, frontal lobe, inferior parietal lobule, and the right supplementary motor area, and an obviously decreased ReHo found in the bilateral occipital lobes, fusiform gyrus, posterior central gyrus, the right posterior cingutate, the left temporal lobe and the left paracentral lobule, etc. after acupuncture of ST 36.
Conclusion: Constitution-associated needling sensation may be an important influential factor for acupuncture analgesia in normal subjects. The change of ReHo in different cerebral areas is probably responsible for the difference of acupuncture analgesia in different constitution people.