mu-opioid receptor-induced Ca2+ mobilization and astroglial development: Morphine inhibits DNA synthesis and stimulates cellular hypertrophy through a Ca2+-dependent mechanism
mu-opioid receptor-induced Ca2+ mobilization and astroglial development: Morphine inhibits DNA synthesis and stimulates cellular hypertrophy through a Ca2+-dependent mechanism
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DOI：
10.1016/0006-8993(96)00103-5
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发表时间：
1996-05-13
期刊：
影响因子：
2.9
通讯作者：
Godleske, CC
中科院分区：
文献类型：
--
作者：
Hauser, KF;StieneMartin, A;Godleske, CC
吗啡是一种优选的μ阿片受体激动剂，通过抑制细胞增殖和促进细胞分化来改变星形胶质细胞的发育。虽然吗啡通过Ca 2+依赖性机制影响细胞分化，但很少有研究探讨Ca 2+是否介导阿片类药物对细胞增殖的影响，或者是否有特定的Ca 2+信号转导途径介导阿片类药物的作用。此外，目前还不确定是否有一种或多种阿片受体类型介导阿片类药物的发育作用。为了解决这些问题，本研究探讨了吗啡诱导的星形胶质细胞发育中μ阿片受体和Ca 2+动员的作用。在补充有< 0.005、0.3、1.0或3.0 mM Ca 2+的无Ca 2+培养基中孵育富含鼠星形胶质细胞的吗啡（1 μ M）和非吗啡暴露的培养物（[Ca 2 +]（o）），或在含有Ca 2+离子载体（A23187）、硝苯地平（1 μ M）、丹曲林（10 μ M）、毒胡萝卜素（100 nM）、或L-谷氨酸（100 μ M）处理0-72小时。使用特异性（MOR 1）抗体免疫细胞化学地检查μ-阿片样受体表达。使用Fura-2通过显微荧光分析测量细胞内Ca 2+（[Ca 2 +]（i））。星形胶质细胞的形态和溴脱氧尿苷（BrdU）的掺入（DNA合成）进行了评估胶质细胞酸性蛋白（GFAP）免疫反应阳性星形胶质细胞。结果表明，吗啡通过激活μ阿片受体抑制星形胶质细胞的生长。星形胶质细胞表达MORI免疫反应性和吗啡的行动模仿的选择性μ激动剂PL 017。此外，吗啡通过动员发育中的星形胶质细胞中的[Ca 2 +]（i）来抑制DNA合成。在正常的[Ca 2 +]（o）下，吗啡通过增加[Ca 2 +]（i）来减弱DNA合成;低[Ca 2 +]（o）（0.3 mM）阻断了这种作用，而用Ca 2+离子载体或谷氨酸处理则模拟了吗啡的作用。在极低的[Ca 2 +]（o）（< 0.005 mM）下，吗啡反而增加了BrdU掺入。虽然阿片类药物可以通过几种途径增加星形胶质细胞中的[Ca 2 +]（i），但并非所有途径都影响DNA合成或细胞形态。硝苯地平（阻断L-型钙通道）没有阻止吗啡诱导的BrdU掺入或细胞分化减少，而毒胡萝卜素（消耗IP 3敏感的Ca 2+商店）严重影响抑制DNA合成和细胞分化，无论吗啡治疗。然而，丹曲林（钙依赖性钙释放的抑制剂）选择性地阻断吗啡的作用。总的来说，研究结果表明，阿片类药物抑制星形胶质细胞DNA合成，并通过抑制钙依赖性钙释放丹曲林敏感的细胞内商店促进细胞肥大。这意味着阿片类药物影响中枢神经系统成熟的基本机制。
Morphine, a preferential mu-opioid receptor agonist, alters astroglial development by inhibiting cell proliferation and by promoting cellular differentiation. Although morphine affects cellular differentiation through a Ca2+-dependent mechanism, few studies have examined whether Ca2+ mediates the effect of opioids on cell proliferation, or whether a particular Ca2+ signal transduction pathway mediates opioid actions. Moreover, it is uncertain whether one or more opioid receptor types mediates the developmental effects of opioids. To address these questions, the present study examined the role of mu-opioid receptors and Ca2+ mobilization in morphine-induced astrocyte development. Morphine (1 mu M) and non-morphine exposed cultures enriched in murine astrocytes were incubated in Ca2+-free media supplemented with < 0.005, 0.3, 1.0, or 3.0 mM Ca2+ ([Ca2+](o)), or in unmodified media containing Ca2+ ionophore (A23187), nifedipine (1 mu M), dantrolene (10 mu M), thapsigargin (100 nM), or L-glutamate (100 mu M) for 0-72 h. mu-Opioid receptor expression was examined immunocytochemically using specific (MOR1) antibodies. Intracellular Ca2+ ([Ca2+](i)) was measured by microfluorometric analysis using fura-2. Astrocyte morphology and bromodeoxyuridine (BrdU) incorporation (DNA synthesis) were assessed in glial fibrillary acidic protein (GFAP) immunoreactive astrocytes. The results showed that morphine inhibited astroglial growth by activating mu-opioid receptors. Astrocytes expressed MORI immunoreactivity and morphine's actions were mimicked by the selective mu agonist PL017. In addition, morphine inhibited DNA synthesis by mobilizing [Ca2+](i) in developing astroglia. At normal [Ca2+](o), morphine attenuated DNA synthesis by increasing [Ca2+](i); low [Ca2+](o) (0.3 mM) blocked this effect, while treatment with Ca2+ ionophore or glutamate mimicked morphine's actions. At extremely low [Ca2+](o) (< 0.005 mM), morphine paradoxically increased BrdU incorporation. Although opioids can increase [Ca2+](i) in astrocytes through several pathways, not all affect DNA synthesis or cellular morphology. Nifedipine (which blocks L-type Ca2+ channels) did not prevent morphine-induced reductions in BrdU incorporation or cellular differentiation, while thapsigargin (which depletes IP3-sensitive Ca2+ stores) severely affected inhibited DNA synthesis and cellular differentiation-irrespective of morphine treatment. However, dantrolene (an inhibitor of Ca2+-dependent Ca2+ release) selectively blocked the effects of morphine. Collectively, the findings suggest that opioids suppress astroglial DNA synthesis and promote cellular hypertrophy by inhibiting Ca2+-dependent Ca2+ release from dantrolene-sensitive intracellular stores. This implies a fundamental mechanism by which opioids affect central nervous system maturation.