Department of Physiology, Faculty of Medicine, University of Alcala, Madrid, Spain.
Mol Pain. 2010 Dec 18;6:95. doi: 10.1186/1744-8069-6-95.
The transcriptional repressor DREAM (downstream regulatory element antagonist modulator) controls the expression of prodynorphin and has been involved in the modulation of endogenous responses to pain. To investigate the role of DREAM in central mechanisms of pain sensitization, we used a line of transgenic mice (L1) overexpressing a Ca(2+)- and cAMP-insensitive DREAM mutant in spinal cord and dorsal root ganglia.
L1 DREAM transgenic mice showed reduced expression in the spinal cord of several genes related to pain, including prodynorphin and BDNF (brain-derived neurotrophic factor) and a state of basal hyperalgesia without change in A-type currents. Peripheral inflammation produced enhancement of spinal reflexes and increased expression of BDNF in wild type but not in DREAM transgenic mice. The enhancement of the spinal reflexes was reproduced in vitro by persistent electrical stimulation of C-fibers in wild type but not in transgenic mice. Exposure to exogenous BDNF produced a long-term enhancement of dorsal root-ventral root responses in transgenic mice.
Our results indicate that endogenous BDNF is involved in spinal sensitization following inflammation and that blockade of BDNF induction in DREAM transgenic mice underlies the failure to develop spinal sensitization.
转录抑制因子 DREAM(下游调节元件拮抗剂调节剂)控制着前脑啡肽原的表达,并参与了内源性疼痛反应的调节。为了研究 DREAM 在疼痛敏化的中枢机制中的作用,我们使用了一种在脊髓和背根神经节中过度表达钙(Ca 2+)和环腺苷酸(cAMP)不敏感的 DREAM 突变体的转基因小鼠(L1)系。
L1 DREAM 转基因小鼠的脊髓中几种与疼痛相关的基因表达减少,包括前脑啡肽原和脑源性神经营养因子(BDNF),并且存在基础痛觉过敏而 A 型电流没有变化。外周炎症导致野生型小鼠脊髓反射增强和 BDNF 表达增加,但 DREAM 转基因小鼠则没有。在野生型小鼠中,持续电刺激 C 纤维可重现脊髓反射的增强,但在转基因小鼠中则不能。外源性 BDNF 的暴露导致转基因小鼠背根-腹根反应的长期增强。
我们的结果表明,内源性 BDNF 参与了炎症后的脊髓敏化,而 DREAM 转基因小鼠中 BDNF 诱导的阻断是其脊髓敏化失败的基础。