100Hz电针耐受时大鼠脑和脊髓k受体结合特性的改变

CHANGES IN THE BINDING CHARACTERISTICS OF CENTRAL K-OPIOID RECEPTOR DURING THE DEVELOPMENT OF 100 Hz ELECTROACUPUNCTURE(EA)TOLERANCE IN RATS

本文采用放射配体结合实验研究了100Hz电针耐受发生发展过程中大鼠脑和脊髓k受体结合特性的变化。大鼠每天给予100Hz电针1次（30min），连续7d。分别在电针的第1.3、5.7天取不同脑区进行观察。结果表明：在100Hz电针耐受期间，大鼠中脑、纹状体、脊髓.皮层和脑桥／延髓的K受体均表现为下调，但在不同脑区K受体下调的时程不同。在大鼠皮层和脑桥／延髓，电针第1天即引起k受体下调，并在全过程（7d）内保持下调状态。脊髓中的k受体先上调后下调，而中脑和纹状体k受体下调的时程与100Hz慢性电针耐受的发生发展相平行，提示该脑区的。受体下调可能参与100Hz慢性电针耐受的形成。大部分脑区k受体对[3H]-U69593亲和力的变化不明显，只有中脑在k受体总数下降的同时亲和力有所升高（Kd值下降）。上述结果表明，每天给予100Hz电针连续7d，引起脑内特别是中脑和纹状体中k受体数目显著下调，这种变化是否参与电针耐受的形成机制值得进一步研究。

The effect of repetitive 100 Hz EA stimulation on the characteristics of binding of Kopioid receptors in discrete brain regions and the spinal cord of rats was investigated by radioligand binding assay. 100 Hz EA was administered once a day (30 min) for 7 d.Changes in Bmax and Kd of K opioid receptors of 4 discrete brain regions (cortex,midbrain, pons-medulla and striatum) and spinal cord were observed at d 1, 3, 5 and 7 ,respectively. It was found that the numbers (Bmax) of K opioid receptors of all the brain regions observed were decreased during the development of 100 Hz EA tolerance with a differential time course . In rat cortex and pens-medulla, a marked down regulation of Kopioid receptors occurred within 24 h and remained at al low level throughout the observation. The Bmax of K receptor in spinal cord showed a bell-shaped curve, i. e., upregulation in the first 5 days and down regulation at d 7. In contrast a slow and steady down regulation was found in the midbrain and striatum, matching the coutrse of develop - ment of 100 Hz EA tolerance. No significant changes in Kd of [3H]-U69593 were found except for a decrease of Kd in midbrain In conclusion, administration of 100 Hz EA 30min per day for 7 consecutive days resulted in a significant down regulation of K opioid receptor in CNS, especially in midbrain and striatum.