Pain-relieving effect of ultrasound-medium frequency electrotherapy and changes of enkephalin in rats
- VernacularTitle:超声-中频电治疗后大鼠脑啡肽水平与其镇痛效应
- Author:
Baocong DU
;
Wei DU
;
Jichao DONG
;
Cheng YU
;
Yan JIN
- Publication Type:Journal Article
- From:
Chinese Journal of Tissue Engineering Research
2006;10(6):182-184
- CountryChina
- Language:Chinese
-
Abstract:
BACKGROUND: Ultrasound-medium frequency electrotherapy has better pain-relieving effect,whether it involves enkephalin and the like neurotransmitter is still not very clear, it is necessary to carry out qualitative and quantitative analysis of the pain response in rats received ultrasound-medium frequency electrotherapy.OBJECTIVE: To investigate the pain-relieving effect of ultrasound-medium frequency electrotherapy and its influence on the enkephalin content in rats, aiming to probe its underlying mechanism and relationship with neurotransmitter enkephalin.DESIGN: Randomly controlled study taking experimental animals as subjects.SETTING: Department of Physiotherapy, First Hospital Affiliated to China Medical University, Institute of Basic Medicine, Peking Union Medical CollegeMATERIALS: This experiment was carried out at the Institute of Basic Medicine, Peking Union Medical College between June 2002 and March 2003. Forty healthy male Wistar rats were adopted and randomized into four groups,namely methionine enkephalin detection experimental group and control group,as well as leucine enkephalin detection experimental group and control group with 10 rats in each group ,amongst which methionine enkephalin experimental group and leucine enkephalin experimental group were generally designed as experimental group ,with the other two group as control group.METHODS: ①Rats ín the experímental group were subjected to ultrasound-medium frequency electrotherapy with frequency of 0.8 MHz in manner of geminal pulse,the modulatìng frequency was 100 Hz and ultrasound intensity of 0.9 W/cm2;the carrier frequency of medium frequency electricity was 4 kHz with modulating frequency of 100 Hz in manner of continuous wave,the electric current of medium frequency was 2 mA and acting time of 10 min. rats in control group received the same dealing,but the higher voltage of ultrasound-medium frequency electrotheprauetic instrument was not used, thereby no energy output was available. tail flick test(TFr) was used to test rat algesthesia,and stopwatch was used to record the time for tail flick(s) that was taken as the value of pain threshold. ②The threshold of pain was tested at 10 minutes instantly after ultrasoundmedium frequency electric stimulation,and then pituitary (removing the posterior pituitary lobe) and hypothalamus were obtained to detect the content of methionine enkephalin and leucine enkephalin by using radioimmuno assay.MAIN OUTCOME MEASURES: The changes of the pain threshold after treatment,the content of methionine enkephalin and leucine enkephalin.RESULTS: Totally 40 rats were enrolled in the experiment and entered in the results analysis. ① The changing rate of pain threshold in two experimental group were 265.79% and 272.90% respectively,the difference was of no statistical significance (P ＞ 0.05). ②After ultrasoundmedium frequency electrotherapy,the content of methionine enkephalin and leucine enkephalin in pituitary and hypothalamus were obviously higher than before treatment [ The changing rate of methionine enkephalin and leucine enkephalin in adenohypophysis was 300.48 ±36.21)% and(204.61±68.65)% , respectively, compared to (239.80±59.98)%and(205.53±51.62)% in hypothalamus, P ＜ 0.05]. ③Linear regression analysis revealed that the variance of the pain threshold was positively correlated with the content of methionine enkephalin in adenohypophysis(r=0.91 ,P ＜ 0.01), suggesting the increment of methionine enkephalin in adenohypophysis was closely connected with the increment of pain threshold,and the level of methionine enkephalin in adenohypophysis would be higher than that in control group by 117.02% when the value of pain threshold increased by100%.CONCLUSION: One of the important mechanisms for the pain-relieving effect of ultrasound-medium frequency electrotherapy might be the increase of methionine enkephalin in adenohypophysis.
