Objective To observe the effect of acupuncture at "open" or "close" time and in "host" or "guest" sequence on uterine contraction in late pregnancy rats so as to explore the regularities of acupoint application.Methods A total of 32 pregnant rats were divided into "open/host-guest"(OHG) group

"open/guest-host"(OGH) group

"close/host-guest"(CHG) group and pregnancy group

with 8 cases in each.Eight normal rats were made up of normal control group.According to Ling Gui Ba Fa(Eight Laws of Spirit Turtle)

acupuncture was given to "Zhaohai"(KI 6)

"Lieque"(LU 7)

"Hegu"(LI 4) and "Sanyinjiao"(SP 6) first or later separately.For example

in OHG group

KI6(host point

being in opening time) was punctured first with the acupuncture needle manipulated for 5 min

then

LU7(guest point) punctured and stimulated for 5 min

LI4(corresponding point of KI6) for 20 min

and then

SP6(another corresponding point) was punctured and stimulated for 5 min in order.In CHG group

KI6(being in closing time) was needled for 5 min first

followed by puncturing LU7

LI4 and SP6 for 5 min

20 min

and 5 min separately in sequence.The uterine tension and uterine contraction frequency were measured by using a tension transducer.Results In comparison with normal control group

uterine smooth muscular tension and contraction frequency increased significantly in model group

and after acupuncture stimulation in OHG

OGH and CHG groups(P<0.01

P<0.05).Compared with model group

uterine tension of CHG group was significantly lower in the 8th time course after acupuncture(15-20 min after removing acupuncture needle

P<0.05).No significant differences were found among model

OHG and OGH groups

and among OHG

OGH and CHG groups in uterine tension and contraction frequency(P>0.05).Conclusion "Close-host-guest needling" can reduce uterine tension

which is likely to have significance in maintaining a stable environment of the uterus during pregnancy.