Shahabi N A, Heagy W, Sharp B M
Endocrine-Neuroscience and Neuroimmunomodulation Research Laboratories, Minneapolis Medical Research Foundation, Minnesota, USA.
Endocrinology. 1996 Aug;137(8):3386-93. doi: 10.1210/endo.137.8.8754765.
Intracellular calcium mobilization is an important early event involved in T cell activation. The endogenous opioid peptide beta-endorphin is known to modulate immune functions that depend on T cell activation, therefore its effect on intracellular calcium mobilization was investigated. The intracellular calcium concentration ([Ca2+]i) of T cell-enriched splenocytes was measured by flow cytofluorometric analysis using the calcium-sensitive dye, Fluo-3. By gating on the T cell marker, Thy-1, a 95%-pure population of T cells was identified for study. Cells preincubated with beta-endorphin showed significantly enhanced [Ca2+]i responses to the mitogen, Concanavalin A (Con A). This was detectable with concentrations of beta-endorphin as low as 10(-13) M; maximal enhancement required 10(-10) to 10(-9) M doses. The efficacy of beta-endorphin was dependent on the duration of pretreatment. beta-Endorphin amplified the Con A-induced increase in [Ca2+]i by reducing the lag time for the response to Con A and by increasing the mean [Ca2+]i of the cells. N-Ac-beta-endorphin, which shows minimal potency at neuronal opiate receptors, was unable to substitute for beta-endorphin. Naltrindole, a highly selective delta opiate receptor antagonist, inhibited the action of beta-endorphin, whereas a selective mu opiate receptor antagonist was ineffective. Although less potent than beta-endorphin, the delta opiate receptor agonist D-Ala2-D-Leu5-enkephalin also significantly enhanced [Ca2+]i responses. In summary, concentrations of beta-endorphin, within the physiological range found in the systemic circulation, modulate the increase in T cell [Ca2+]i induced by Con A. Both the efficacy of D-Ala2-D-Leu5-enkephalin alone and the antagonism of beta-endorphin by naltrindole suggest that a delta-type opiate receptor may mediate these effects.
细胞内钙动员是T细胞活化过程中一个重要的早期事件。内源性阿片肽β-内啡肽已知可调节依赖于T细胞活化的免疫功能，因此研究了其对细胞内钙动员的影响。使用钙敏染料Fluo-3通过流式细胞荧光分析测量富含T细胞的脾细胞的细胞内钙浓度（[Ca2+]i）。通过门控T细胞标志物Thy-1，鉴定出95%纯度的T细胞群体用于研究。用β-内啡肽预孵育的细胞对促有丝分裂原刀豆球蛋白A（Con A）表现出显著增强的[Ca2+]i反应。β-内啡肽浓度低至10^(-13) M时即可检测到这种反应；最大增强需要10^(-10)至10^(-9) M的剂量。β-内啡肽的功效取决于预处理的持续时间。β-内啡肽通过减少对Con A反应的延迟时间并增加细胞的平均[Ca2+]i来放大Con A诱导的[Ca2+]i增加。N-乙酰-β-内啡肽在神经元阿片受体上的效力极小，无法替代β-内啡肽。纳曲吲哚是一种高度选择性的δ阿片受体拮抗剂，可抑制β-内啡肽的作用，而选择性μ阿片受体拮抗剂则无效。虽然效力低于β-内啡肽，但δ阿片受体激动剂D-Ala2-D-Leu5-脑啡肽也显著增强了[Ca2+]i反应。总之，在体循环中发现的生理范围内的β-内啡肽浓度可调节Con A诱导的T细胞[Ca2+]i增加。D-Ala2-D-Leu5-脑啡肽单独的效力以及纳曲吲哚对β-内啡肽的拮抗作用均表明，δ型阿片受体可能介导这些效应。
