Krivoshein Georgii, Della Pietra Adriana, Savinainen Juha, van den Maagdenberg Arn M J M, Giniatullin Rashid
Department of Human Genetics, Leiden University Medical Center, Leiden, The Netherlands.
A.I. Virtanen Institute for Molecular Sciences, University of Eastern Finland, Kuopio, Finland.
J Headache Pain. 2025 May 12;26(1):112. doi: 10.1186/s10194-025-02041-z.
Increasing endocannabinoids (endoCBs), anandamide (AEA) and 2-arachidonoylglycerol (2-AG), through inhibition of the degrading hydrolase enzymes, fatty acid amide hydrolase (FAAH) and monoacylglycerol lipase (MAGL), respectively, has been proposed as approach to alleviate migraine pain. Notwithstanding, the impact of AEA and 2-AG on neuronal firing of meningeal afferents, which is relevant to the genesis of migraine pain, remains elusive.
The impact of AEA and 2-AG on meningeal nerve afferent firing was examined through electrophysiological evaluation upon application of 50 mM KCl with or without DMSO, exogenous AEA (10 µM), or 2-AG (10 µM) to separate groups of C57BL/6J mouse hemiskull preparations. At the end of each experiment, capsaicin (1 µM), an agonist of TRPV1 channels, was tested, as a positive control of presumably nociceptive firing. Advanced clustering and spectral analysis on the electrophysiological data allowed differentiating spiking patterns with respect to their temporal and neurochemical profiles. Activity-based protein profiling and liquid chromatography with tandem mass spectrometry was used to assess endogenous FAAH and MAGL activity and determine endogenous levels of AEA and 2-AG in mouse meninges.
Local application of endoCBs decreased KCl-induced firing of meningeal nerve afferents, which was most profound for AEA. AEA first produced a short, mild activation in firing, which was followed by a long-lasting reduction. Instead, 2-AG directly led to a short-lasting reduction in firing. Cluster analysis revealed that the transient activation by AEA involved fibers with small-amplitude spikes fired at rates of 1-2 Hz, whereas the persistently suppressed fibers consisted of high-amplitude spikes fired at rates exceeding 10 Hz. Only AEA inhibited subsequent capsaicininduced firing in the afferents long after AEA application, suggesting a broader mode of action for AEA than 2-AG. The more profound inhibitory effects of AEA are consistent with the observed higher activity of FAAH over MAGL and lower level of endogenous AEA than 2-AG in mouse meninges.
Our study revealed a stronger anti-nociceptive action of AEA than of 2-AG, as measured by meningeal afferent firing in mouse hemiskulls. This difference can be exploited for relieving migraine pain by primarily increasing the tone of AEA through inhibition of FAAH outside the central nervous system.
通过分别抑制降解水解酶——脂肪酸酰胺水解酶（FAAH）和单酰甘油脂肪酶（MAGL）来增加内源性大麻素（endoCBs）、花生四烯酸乙醇胺（AEA）和2-花生四烯酸甘油（2-AG），已被提议作为缓解偏头痛疼痛的一种方法。尽管如此，AEA和2-AG对脑膜传入神经放电的影响（这与偏头痛疼痛的发生有关）仍不清楚。
通过电生理评估，在向C57BL/6J小鼠半颅骨制备物的不同组施加50 mM氯化钾（含或不含二甲基亚砜）、外源性AEA（10 μM）或2-AG（10 μM）时，检测AEA和2-AG对脑膜神经传入放电的影响。在每个实验结束时，测试辣椒素（1 μM）（一种TRPV1通道激动剂）作为可能的伤害性放电的阳性对照。对电生理数据进行先进的聚类和频谱分析，可以根据其时间和神经化学特征区分放电模式。基于活性的蛋白质谱分析和液相色谱-串联质谱法用于评估内源性FAAH和MAGL活性，并测定小鼠脑膜中AEA和2-AG的内源性水平。
局部应用内源性大麻素可降低氯化钾诱导的脑膜神经传入放电，其中AEA的作用最为显著。AEA首先产生短暂、轻微的放电激活，随后是长期的减少。相反，2-AG直接导致放电短暂减少。聚类分析显示，AEA引起的短暂激活涉及以1-2 Hz频率发放小幅度尖峰的纤维，而持续受抑制的纤维则由以超过10 Hz频率发放大幅度尖峰的纤维组成。只有AEA在应用后很长时间抑制了随后辣椒素诱导的传入神经放电，这表明AEA的作用模式比2-AG更广泛。AEA更显著的抑制作用与在小鼠脑膜中观察到的FAAH活性高于MAGL以及内源性AEA水平低于2-AG一致。
我们的研究表明，以小鼠半颅骨中的脑膜传入放电来衡量，AEA的抗伤害作用比2-AG更强。这种差异可通过在中枢神经系统外抑制FAAH来主要增加AEA的水平，从而用于缓解偏头痛疼痛。
