PUTATIVE PAIN MODULATING NEURONS IN THE ROSTRAL VENTRAL MEDULLA - REFLEX-RELATED ACTIVITY PREDICTS EFFECTS OF MORPHINE
PUTATIVE PAIN MODULATING NEURONS IN THE ROSTRAL VENTRAL MEDULLA - REFLEX-RELATED ACTIVITY PREDICTS EFFECTS OF MORPHINE
复制标题
DOI：
10.1016/0006-8993(86)91296-5
复制
发表时间：
1986-02-26
期刊：
影响因子：
2.9
通讯作者：
FIELDS, HL
中科院分区：
文献类型：
--
作者：
BARBARO, NM;HEINRICHER, MM;FIELDS, HL
在延髓头端腹内侧（RVM）发现了三种生理上定义的神经元，该区域有助于阿片类药物的抗伤害作用。离体细胞在甩尾反射（TF）发生之前出现突然停顿。在细胞上显示在TF发生之前开始的活性爆发。中性细胞放电不随TF的变化而变化。已显示吗啡的全身施用产生离体细胞活性的一致增加。在本研究中，在轻度麻醉的大鼠中，研究了全身给予吗啡对上细胞和中性细胞的自发和TF相关活动的影响。在吗啡（1.25-2.5 mg/kg，i. v.）之前和之后获得自发活动的测量。上细胞表现出不规则的周期性自发放电率类似于先前报道的关闭细胞。相反，中性细胞具有几乎恒定的自发活动水平。吗啡给药后，自发活动停止了8个上细胞，热相关的活动被消除。纳洛酮给药导致与TF相关的周期性放电模式和爆发的恢复。吗啡给药后，8个中性细胞中有7个的放电频率没有变化，1个的放电频率下降。这些结果表明，全身阿片类药物对RVM神经元的影响可以根据细胞在伤害性反射发生之前是否增加或减少其放电来预测。他们增加了现有的证据表明，在脊髓水平的伤害性传递和伤害性反射的调制中涉及的上细胞和关细胞，并表明这些神经元有助于阿片类药物诱导的镇痛。
Three physiologically-defined classes of neurons are found in the rostral ventromedial medulla (RVM), a region which contributes to the antinociceptive action of opiates. The off-cell exhibits an abrupt pause just prior to the occurrence of the tail flick reflex (TF). The on-cell shows a burst of activity beginning just prior to the occurrence of the TF. Neutral cell firing does not change in relation to the TF. Systemic administration of morphine has been shown to produce a consistent increase in the activity of off-cells. In the present studies, the effects of systemically-administered morphine on spontaneous and TF-related activity of on-cells and neutral cells were examined in lightly-anesthesized rats. Measures of spontaneous activity were obtained before and after morphine (1.25-2.5 mg/kg, i.v.). On-cells exhibited an irregular cyclic rate of spontaneous discharge similar to that previously reported for off-cells. In contrast, neutral cells had nearly constant level of spontaneous activity. After administration of morphine, spontaneous activity ceased for 8 of 8 on-cells, and heat-related activity was eliminated. Administration of naloxone resulted in a return of the periodic firing pattern and the burst associated with the TF. Seven of 8 neutral cells showed no change in firing rate and one showed a decreased rate after morphine administration. These results show that the effect of systemic opiates on an RVM neuron can be predicted based on whether a cell increases or decreases its firing just prior to the occurrence of a nocifensive reflex. They add to the existing body of evidence implicating both on-and off-cells in modulation of nociceptive transmission and nocifensive reflexes at spinal levels and indicate that these neurons contribute to opiate-induced analgesia.