The Study On Pain Threshold And Prodynorphin Gene Expression Level In The Central Nerve System Of Goats Following Electroacupuncture

Veterinary clinical research has shown that acupuncture analgesia in the ruminants emerges the obvious after-effect, and can be maintained 30 min, time for the elderly 2 h, even more than 48 h. The analgesic after-effect can significantly relief postoperative pain, at the same time, plays an important role in the treatment of pain diseases. The release of central neuromodulator can explain the immediate analgesic effects of ruminant animals, but difficult to make a reasonable explanation for after-effects of acupuncture analgesia.As a member of the family of opioid peptides, dynorphin has a lasting and powerful analgesic effect and it's one of major central opioid substances involved in regulating acupuncture analgesia. In this study, basing on the material perspective, we reseached into the regularity of time course of pain threshold and prodynorphin mRNA expression in central nerve system of goats following electroacupuncture, and offered a theoretical basis for the in-depth exploration of molecular mechanism about acupuncture analgesia in ruminants.42 healthy male cross-breeding goats weighing from 25 to 30 kg were randomly divided into 2 groups:control group and electroacupuncture(EA) group. Control group contained 6 goats, and EA group contained 36 goats. EA stimulated "Baihui-Qijia", "Ergen-San yang luo" points of goats for 30 min at 60 Hertz, and then measured the pain threshold of EA group by potassium ion penetration method at 0 h,2 h,4 h,6 h,8 h,12 h, 24 h after the termination of EA. At the same time, we made use of real-time quantitative PCR to detect prodynorphin mRNA expression and variation trends of striaturn, amygda-loid nucleus, paraventricular nucleus of thalamus, ventromedial nucleus of hypothalamus, paraventricular nucleus of hypothalamus, supraoptic nucleus, periaqueductal gray, para-brachial nucleus, nucleus of solitary tract and cervical spinal cord at 2 h,4 h,6 h,8 h,12 h,24 h after the termination of EA.Pain threshold determination results showed: Compared with the goats of control group, pain threshold of goats at 0 h,2 h,4 h,6 h,8 h,12 h and 24 h after the termination of EA increased by 87.7%,47.2%,31.5%,23.6%,45.5%,20.5% and 12.3% respectively. Among them, the increase rate difference at 2 h and 8 h,6 h and 12 h after the termination of EA was not significant (P> 0.05), difference of other time courses were significant (P <0.05). It showed that analgesic effects of electroacupuncture has analgesic effect on goat, and this effect can last for more than 24 h.Real-time quantitative PCR results exhibited that: PDYN gene expressed in striaturn, amygdaloid nucleus, paraventricular nucleus of thalamus, ventromedial nucleus of hypo-thalamus, paraventricular nucleus of hypothalamus, supraoptic nucleus, periaqueductal gray, parabrachial nucleus, nucleus of solitary tract and cervical spinal cord of goats. Compared with the the control group, PDYN mRNA expression of all nuclei upregulated at whole time courses except that the striatum slightly downregulated at 2 h after the termination of EA. The expression reached the peak at 12 h after the temination of EA, higher than the one of control group for 2 to 3 times, and was significantly different form other time courses (P<0.05). The PDYN mRNA expression variation tendency of paraventricular nucleus of hypothalamus, ventromedial nucleus of hypothalamus, supraoptic nucleus and nucleus of solitary tract are consistent. Striatum, periaqueductal gray, amygdaloid nucleus, paraventricular nucleus of thalamus, parabrachial nucleus and spinal cord have the same PDYN gene expression variation tendency. The general trend is: PDYN gene expression began to increase at 2 h after the temination of EA, arrived the peak value at 12 h after the temination of EA and then declined gradually, the expression at 24 h is still higher than the one of control group. It indicated that acupuncture promoted the PDYN mRNA expression of goats, and this strengthened action can maintain more than 24 h. The results prompted that the accelerated expression of PDYN gene involved in the after-effect modulation of acupuncture analgesia.