Benoist J M, Kayser V, Gautron M, Guilbaud G
Pain. 1983 Apr;15(4):333-44. doi: 10.1016/0304-3959(83)90070-2.
Effects of low intravenous doses of morphine (30, 100 and 1000 micrograms/kg) upon unitary responses of 22 'nociceptive' and 5 'non-nociceptive' units recorded in the ventrobasal (VB) complex of the rat were analyzed. The responses of the 'non-noxious' neurones were not depressed by morphine. By contrast, for all these doses there was a decrease of the total number of spikes and of the maximal firing rate of the responses of the noxious neurones. The depressive effect was significantly dose-related (with linear semi-logarithmic dose-response curve) and naloxone-reversible. Similar effects were observed upon responses to pinches and noxious heat. The ED50 which was close to 90 micrograms/kg for these thalamic responses to pinches is much more lower than that evaluated for spinal dorsal horn responses under the same anaesthetic conditions. Therefore the depressive effect of low doses observed for VB neurones seems to be mainly of supraspinal origin.
分析了静脉注射低剂量吗啡（30、100和1000微克/千克）对在大鼠腹侧基底（VB）复合体中记录的22个“伤害性”和5个“非伤害性”单位的单一反应的影响。“非伤害性”神经元的反应未被吗啡抑制。相比之下，对于所有这些剂量，伤害性神经元反应的总尖峰数和最大放电率均降低。这种抑制作用与剂量显著相关（呈线性半对数剂量反应曲线）且可被纳洛酮逆转。对捏压和伤害性热的反应也观察到类似效果。这些丘脑对捏压反应的ED50接近90微克/千克，远低于在相同麻醉条件下对脊髓背角反应评估的ED50。因此，观察到的低剂量对VB神经元的抑制作用似乎主要源于脊髓上。
