[Regulative effect of electroacupuncture on hypothalamus-hypophysis-gonad axis in different stages of estrous cycles in rats].

Objective: To investigate the specific acupoint, optimal curative opportunity and the involved pathway of electroacupuncture (EA) for regulating gono-endocrine hormones.

Methods: (1) Adult female rats were randomly divided into sham-EA group (n = 32), "Guanyuan" (CV 4) group (n = 36) and "Neiguan" (PC 6) group (n = 36) which were further divided into diestrum, preoestrus (P-EST), estruation and metaoestrus subgroups according to tetra-estrous cycles determined by vaginal smear test. EA (20/60 Hz, 2-3 mA) was applied to CV4 and PC6 separately for 30 min from about 9:30 to 10:00 Am. Blood samples were collected from the common iliac vein before, 30 min and 60 min after EA for detecting serum gonadotropin-releasing hormone (GnRH) and luteotropic hormone (LH) contents with radioimmunoassay. (2) Other female rats were randomly divided into median eminence (ME) lesions group and control group, which were used to observe the influence of hypothalamic ME lesion on the effect of EA of CV4 in regulating GnRH, LH and estradiol (E2) levels.

Results: JD Before the treatment, serum GnRH and LH levels were slightly different in different stages of the estrous cycle, GnRH level was highest in the estruation and LH content highest in the preoestrus. (2) After EA, both serum GnRH and LH levels increased to a certain degree at most stages. Compared with sham-EA group, GnRH levels in the diestrum and metaoestrus and LH in all the 4 stages of the estrous cycle in CV4 group increased significantly (P < 0.05, 0.01). Self-comparison showed that after EA of CV4, serum GnRH level in diestrum and metaoestrum, and LH contents in diestrum and metaoestrus increased markedly (P < 0.05, 0.01); while after EA of PC6, serum GnRH and LH levels in diestrum and metaoestrum increased slightly, suggesting that the effect of EA of CV4 was superior to that of EA of PC6 in promoting secretion of GnRH and LH. (Thirty minutes after EA, self-comparison between pre-and post-EA in each group and comparison among 3 groups showed no significant differences in both serum GnRH and LH levels (P > 0.05). (4) Electrolytic lesion weakened the effects of EA in promoting the secretion of GnRH, LH and E2, though the influence of this lesion on GnRH secretion was milder.

Conclusion: EA can enhance the secretion of GnRH and LH in the diestrum and metaoestrus of the estrous cycle, which is realized by the hypothalamus-pituitary-gonad axis. The effect of EA of CV4 is better than that of PC6.