大鼠尾核痛反应神经元放电和甩尾反射关系的研究

STUDIES ON RELATIONSHIP BETWEEN ACTIVITIES OF PAIN REACTING NEURONS IN CAUDATE NUCLEI AND TAIL FLICK IN RATS

用浅麻醉的Ｗｉｓｔａｒ大鼠４０只，以辐射热照尾作为伤害性刺激，经玻璃微电极引导尾核痛兴奋神经元（ＰＥＮ）和痛抑制神经元（ＰＩＮ）的放电，同时测量甩尾反射潜伏期（ＴＦＬ）作为甩尾痛阈的指标。结果表明：（１）自然状态下辐射热照尾引起尾核中ＰＥＮ放电频率增加和ＰＩＮ放电频率减少与甩尾反射（ＴＦ）相伴行。放电变化发生在ＴＦ之前，结束在ＴＦ之后，ＰＥＮ和ＰＩＮ放电变化与ＴＦＬ呈高度正相关。（２）辐射热照尾同时引起一侧尾核ＰＥＮ放电频率增加和另一侧ＰＩＮ放电频率减少，二者协同活动，并发生在ＴＦ之前，结束在ＴＦ之后。（３）侧脑室注射５５μｇ／１０μｌ吗啡呈镇痛作用时，尾核ＰＥＮ放电频率减少和ＰＩＮ放电频率增加，放电变化仍发生在ＴＦ之前，结束在ＴＦ之后。结果提示，尾核中ＰＥＮ、ＰＩＮ放电和ＴＦ是中枢不同水平同时对痛觉调制所产生的结果。

The activities of pain reacting neurons in caudate nuclei (N. Cd) and tail flick (TF) were studied in forty lightly anesthetized Wistar rats. The radiant heat focused on tail was used as noxious stimulation, and the latency of tail flick (TFL) was used as an indication of pain threshold. The results were as follows: 1 . In a natural state, the increase in firing rate of pain excitation neurons (PEN) occurred about 0.94±0.41s before TF and stopped after TF. There was an obvious correlation between TFL and latency of discharge change (r=0.91).2. The decrease in activities of pain inhibition neurons (PIN) occurred about 0.99±0.49s before TF, and stopped after TF. A strong correlation between TFL and latency of discharge change of PIN (r = 0.85) was also observed. 3. The activities of PEN and PIN in response to the radiant heat were well coordinated. 4.When the pain threshold was elevated after injecting morphine into the lateral ventricle, the discharge change of PEN and PIN still occurred before TF and stopped after TF. The results suggest that the discharge change of PEN and PIN in N. Cd and TF are the results of simultaneous modulation of pain by different parts of CNS.