Effects of timing acupuncture on nuclear volume of neurosecretory cells in rat supraoptic nucleus.

To see whether the effects of acupuncture on the nuclear volume of neurosecretory cells in the rat supraoptic nucleus (SON) are circadian stage-dependent, 48 male Wistar rats were divided into eight equal groups and standardized in LD12:12 at 21.5 degrees C with food and water ad libitum. At each of four time points [0, 6, 12, and 18 hours after lights on (HALO)], one group (A) was treated by electric acupuncture at a place equivalent to the human "Yongquan" point; another group (C) was left untreated as a control without acupuncture. The nuclear volumes of neurosecretory cells were calculated after the nuclei were measured with a micrometer under a microscope. Circadian variation in nuclear volume was observed for both A and C groups and showed macroscopically two peaks, one at 18 HALO and another at 6 HALO, and a nadir at the time of lights on (0 HALO). The effects of acupuncture appear to differ at various time points. A circadian change in the ratio of the data from the A and C groups at each time point was observed only in the left SON and peaked at 0 HALO. An asymmetry between the left and right SONs characterized their changes and responses to acupuncture. An analysis of variance established a time effect (P less than 0.001) and an interaction between laterality and treatment (P less than 0.037). The results documenting a circadian change of nuclear volume of the SON neurosecretory cells and a laterality-dependent response to acupuncture point to cephalic mechanisms of "Ziwu Liuzhu" chronotherapy by acupuncture and moxibustion.