Institute for Anatomy, Leipzig University, Leipzig, Germany.
PLoS One. 2012;7(3):e33537. doi: 10.1371/journal.pone.0033537. Epub 2012 Mar 22.
After focal neuronal injury the endocannabinioid system becomes activated and protects or harms neurons depending on cannabinoid derivates and receptor subtypes. Endocannabinoids (eCBs) play a central role in controlling local responses and influencing neural plasticity and survival. However, little is known about the functional relevance of eCBs in long-range projection damage as observed in stroke or spinal cord injury (SCI).
In rat organotypic entorhino-hippocampal slice cultures (OHSC) as a relevant and suitable model for investigating projection fibers in the CNS we performed perforant pathway transection (PPT) and subsequently analyzed the spatial and temporal dynamics of eCB levels. This approach allows proper distinction of responses in originating neurons (entorhinal cortex), areas of deafferentiation/anterograde axonal degeneration (dentate gyrus) and putative changes in more distant but synaptically connected subfields (cornu ammonis (CA) 1 region).
Using LC-MS/MS, we measured a strong increase in arachidonoylethanolamide (AEA), oleoylethanolamide (OEA) and palmitoylethanolamide (PEA) levels in the denervation zone (dentate gyrus) 24 hours post lesion (hpl), whereas entorhinal cortex and CA1 region exhibited little if any changes. NAPE-PLD, responsible for biosynthesis of eCBs, was increased early, whereas FAAH, a catabolizing enzyme, was up-regulated 48hpl.
Neuronal damage as assessed by transection of long-range projections apparently provides a strong time-dependent and area-confined signal for de novo synthesis of eCB, presumably to restrict neuronal damage. The present data underlines the importance of activation of the eCB system in CNS pathologies and identifies a novel site-specific intrinsic regulation of eCBs after long-range projection damage.
在局灶性神经元损伤后，内源性大麻素系统被激活，并根据大麻素衍生物和受体亚型对神经元产生保护或损伤作用。内源性大麻素（eCBs）在控制局部反应和影响神经可塑性和存活方面发挥着核心作用。然而，对于在中风或脊髓损伤（SCI）中观察到的长程投射损伤中 eCB 的功能相关性，人们知之甚少。
在大鼠器官型内嗅-海马切片培养物（OHSC）中，作为研究中枢神经系统投射纤维的相关和合适模型，我们进行了穿通通路横断（PPT），并随后分析了 eCB 水平的时空动态。这种方法允许在起源神经元（内嗅皮层）、去神经/顺行轴突退化区域（齿状回）以及假定的更远但突触连接的亚区（CA1 区）中适当区分反应。
使用 LC-MS/MS，我们在损伤后 24 小时（hpl）测量到脱神经区（齿状回）中花生四烯酰乙醇胺（AEA）、油酰乙醇胺（OEA）和棕榈酰乙醇胺（PEA）水平的强烈增加，而内嗅皮层和 CA1 区几乎没有变化。NAPE-PLD 负责 eCB 的生物合成，早期增加，而 FAAH，一种分解代谢酶，在 48hpl 时上调。
通过长程投射的横断评估的神经元损伤显然提供了一个强烈的时间依赖性和区域受限的信号，用于内源性大麻素的新合成，可能是为了限制神经元损伤。本研究数据强调了内源性大麻素系统在中枢神经系统病理中的重要性，并确定了长程投射损伤后 eCB 的新的特定部位的内在调节。
