[Effect of acupuncture of different acupoints on electrical activities of hypothalamic sexual arousal stimulation-related neurons at different stages of oestrous cycle in rats].

OBJECTIVE: To compare the effects of acupuncture stimulation of different acupoints on discharges of hypothalamic sexual arousal stimulation-related excitatory neurons in the rat so as to selected effective acupoints for regulating genito-endocrine function.

METHODS: Experiments were performed in 32 female Sprague-Dawley rats. Examination of vaginal castoff cell smear (HE staining) was performed to determine the rats' estrous cycle. Those being in proestrus/estrus were 14 animals and those being in diestrus/metaestrus were 18. Extracellular discharges of neurons within the medial preoptic area, the arcuate nucleus and the paraventricular nucleus of the hypothalamus (AP: 4.0-9.0 mm, R: <1.0 mm, L: <2.0 mm) were recorded by using glass micro-pipettes in anesthetized rats (10% urethane). Sexual arousal stimulation was made by using a cotton-ball-stick to touch the clitoris repeatedly (30 s). When a marked change of the neuronal firing rate was found, beta-estradiol (20 ng/mL, 1.5-2.5 mL/kg) was injected intravenously from the external jugular vein for observing its feedback regulatory effect. Acupoints "Neiguan" (PC6), "Shanzhong" (CV17), "Jueyinshu" (BL14), "Zhongwan" (CV12), Shenshu" (BL23), "Guanyuan" (CV4), Z"igong" (EX-CA ) and "Zusanli" (ST 6) were punctured and stimulated manually by twirling the acupuncture needle continuously for 30 s. RRESULTS After manual acupuncture, the sequence of acupoints with a stronger excitatory reaction of the firing rates of the hypothalamic neurons related to sexual arousal stimulation was EX-CA1, CV4, ST36, BL23, CV12, BL14, PC6 and CV17 in proestrus/estrus; and CV4, EX-CA1, ST36, CV12, BL23, BL14, PC6 and CV17 respectively in diestrus/metaestrus. According to the place of the stimulated acupoints potentiating the electrical activity of the hypothalamic sexual arousal stimulation-related neurons, the sequence from stronger to the weaker responses was lower abdomen (below umbilicus), lower limb, lower back (L1-S5), upper abdomen, upper back (above T12), thorax, and upper limbs. After administration of estradiol, the excitatory response of these sexual arousal-related neurons decreased significantly in both estrus and non-estrus (P<0.05).

CONCLUSION: Acupuncture can effectively activate the electrical activity of hypothalamic sexual arousal stimulation-related excitatory neurons. The closer the acupoint to the genital organs, the stronger is the excitatory effect, including "Zigong" (EX-CA1), "Guanyuan" (CV4) and "Zusanli" (ST36) among the 8 acupoints observed.