Seutin V, Franchimont N, Massotte L, Dresse A
Laboratory of Pharmacology, University of Liege, Belgium.
Life Sci. 1990;46(25):1879-85. doi: 10.1016/0024-3205(90)90241-i.
Extracellular single-cell recordings were performed on rat brain slices to compare the effects of morphine on noradrenergic neurons of the locus coeruleus (LC) and on dopaminergic neurons of the ventral tegmental area (VTA). Morphine inhibited the firing of LC neurons at very low concentrations. The mean IC50 was 13.4 +/- 1nM (mean +/- SEM) (n = 7). Moreover, the inhibitory effect of morphine was identical in slices obtained from rats anesthetized with chloral hydrate or from non-anesthetized rats. On the contrary, morphine did not have any influence on the firing of most VTA neurons (N = 20) up to 100 microM, and did not modify the sensitivity of their autoreceptors (N = 8). It is concluded that morphine potently inhibits the firing of LC neurons in vitro both in slices of anesthetized and not anesthetized animals and has no direct excitatory effect on VTA dopaminergic neurons of the rat.
在大鼠脑片上进行细胞外单细胞记录，以比较吗啡对蓝斑（LC）去甲肾上腺素能神经元和腹侧被盖区（VTA）多巴胺能神经元的作用。吗啡在极低浓度下就能抑制LC神经元的放电。平均半数抑制浓度（IC50）为13.4±1纳摩尔（平均值±标准误）（n = 7）。此外，在用氯水合醛麻醉的大鼠或未麻醉的大鼠获取的脑片中，吗啡的抑制作用是相同的。相反，高达100微摩尔时，吗啡对大多数VTA神经元（N = 20）的放电没有任何影响，也不会改变其自身受体的敏感性（N = 8）。得出的结论是，吗啡在体外能有效抑制麻醉和未麻醉动物脑片中LC神经元的放电，且对大鼠VTA多巴胺能神经元没有直接兴奋作用。
