ObjectiveTo explore the correlation between blood oxygen level dependent functional magnetic resonance imaging(BOLD-fMRI)signal and neurotransmitter γ-aminobutyric acid(GABA)concentration in the prefrontal cortex area after acupuncture or Von Frey filament stimulation(epidermal stimulation)at the right Hegu(LI4).MethodsA total of 76 healthy volunteers(23 men and 53 women

24. 5±1. 4 years in age)were recruited in the present study. Each volunteer received two sessions of fMRI magnetic resonance scanning(MRS)examinations

with an interval of one week between two sessions. The MRI scan sequences included pre-task MRS

resting state BOLD and task MRS

BOLD. A region of Interest(ROI)of 35 mm×30 mm×25 mm was located at the bilateral medial prefrontal cortex areas. In the two sessions of examinations

the right LI4 point was stimulated by manual acupuncture or Von Frey filament-pressing. The tasks were designed as the block design. Each block contained 3 intermittent acupoint stimulations

lasting 30 s in each stimulation and with two minutes' pause between two stimulations. The MRS data were processed by using Linear Combination(LC)Model software(for assessing GABA content)

and the BOLD data of fMRI was analyzed by using SPM12 software(comparison within each group)

REST1. 8(comparison between two groups)

separately.ResultsExtensive deactivations were induced by both stimulations

mainly involving the midline regions as the medial prefrontal lobe

and limbic lobe. The deactivation effect of manual acupuncture stimulation was more extensive and intensive than that of Von Frey filament stimulation

especially in the medial prefrontal lobe. Data from 66 volunteers(after exclusion of 10 participants due to bigger standard deviation of GABA/Glx)showed no marked correlation between the GABA concentration and BOLD activation in the anterior cingulate cortex area in both groups(manual acupuncture stimulation group:r=-0. 07

-0. 08

0. 04;P=0. 57

0. 88

0. 74;Von Frey filament epidermal stimulation group:r=-0. 10

-0. 09

-0. 01;P=0. 43

0. 46

0. 96).ConclusionAcupuncture of LI4 elicits a stronger and broader negative activation effect in the limbic-paralimbic-neocortical network including the medial prefrontal cortex in comparison with Von Frey filament stimulation

but no apparent correlation was found between the GABA concentration and BOLD activation in the anterior cingulate cortex after manual acupuncture and Von Frey stimulation.