Objective To observe the effect of manual acupuncture stimulation of different layers(skin

muscle

peritoneum

sub-peritoneum)of"Tianshu"(ST 25)region on proximal colonic pressure in normal rats.Methods Forty-eight male SD rats were divided into 6 groups:all layer-needling

brushing

cutaneous needling

muscular needling

peritoneum-needling and sub-peritoneum-needling groups(n=8 in each group).Manual needling or brushing was applied to "Tianshu"(ST 25)region.The colonic internal pressure was measured by using an amplifier and a pressure transducer-connected balloon which was implanted into the colonic cavity about 6 cm from the ileocecal valve.For rats of the all-layer needling group

an acupuncture needle was inserted into ST 25 about 1 cm deep and rotated for a while

for rats of the brushing group

a Chinese calligraphy brush pen was used to brush the skin hair for 1 min.For rats of the rest 4 groups

an acupuncture needle was inserted into the skin

muscle layer after cutting open the skin(about 0.1 cm)

the peritoneum layer after cutting open the skin and muscle layers

and the sub-peritoneum layer after cutting open the skin

muscle and peritoneum layers

respectively

and rotated using the uniform reinforcing-reducing technique for about 1 min at a frequency of 120 twirlings per minute every time.Results During manual needling stimulation of the full layers

cutaneous layer

muscle layer

peritoneum layer and the sub-peritoneum layer of bilateral"Tianshu"(ST 25)

the internal pressure of proximal colon was significantly decreased relevant to pre-stimulation in each group(P<0.05)

and there were no significant differences between bilateral sides needling stimulation in the decreased pressure levels(P>0.05).During hair brushing of ST 25 region

the colonic pressure was observably increased relevant to pre-needling stimulation(P<0.05).One min after the acupuncture stimulation

the decreased pressures maintained in needling the all-layer on the left side

needling the skin on the right side

needling the peritoneum layer on both sides

and needling the sub-peritoneum layer on both sides relevant to the brushing group of the same side(P<0.05).Conclusion Manual acupuncture stimulation of each layer tissue of ST 25 on both sides may lower internal pressure of proximal colon in normal rats

suggesting their involvement of acupuncture effect in relaxing proximal colonic contraction.