de Abreu Mariana Murta, Binda Nancy Scardua, Reis Marcos Paulo Ferreira Corrêa Alves, Diniz Danuza Montijo, Cordeiro Marta do Nascimento, Borges Márcia Helena, de Lima Maria Elena, Ribeiro Fabíola Mara, Gomez Marcus Vinícius, da Silva Juliana Figueira
Department of Pharmacy, Federal University of Ouro Preto (UFOP), Ouro Preto, MG, Brazil.
Center of Technology in Molecular Medicine, School of Medicine, Federal University of Minas Gerais (UFMG), Belo Horizonte, MG, Brazil.
J Venom Anim Toxins Incl Trop Dis. 2024 Nov 25;30:e20230103. doi: 10.1590/1678-9199-JVATITD-2023-0103. eCollection 2024.
Medications currently used to treat pain are frequently associated with serious adverse effects and rapid development of tolerance. Thus, there is a need to develop more effective, and safer medicines for the population. Blocking NMDA receptors (NMDAR) has shown to be a promising target for the development of new drugs. That statement is due to NMDAR activation and glutamate release in the spinal cord which affects chronic pain modulation. Therefore, the aim of this study was to evaluate the possible spinal antinociceptive activity of PnTx4(5-5) toxin. The peptide is purified from the venom of the spider and its affinity for NMDAR and sodium channels Nav1.2-1.6 has already been established.
We compared its effect and safety with MK-801 (NMDAR antagonist) and evaluated its influence on glutamate and reactive oxygen species (ROS) levels in CSF. PnTx4(5-5) was administered intrathecally in the Formalin test and co-administered with NMDA in the Spontaneous pain test. After three minutes of observation, mice cerebrospinal fluid was collected to measure glutamate and ROS levels.
The spider peptide inhibited nociception as post-treatment in the inflammatory phase of the Formalin test. Furthermore, it inhibited spontaneous nociception induced by NMDA, being more potent and effective than MK-801 in both models tested. A glutamate rise level in the CSF of mice was significantly reduced by the toxin, but ROS increase was not affected. The animals' motor skills were not affected by the tested doses of NMDAR inhibitors.
In conclusion, the results suggest PnTx4(5-5) may mediate its antinociceptive effect in the spinal cord not only by inhibiting postsynaptic receptors but probably also by acting on autoreceptors. This effect does not affect the motricity of mice at the highest dose tested, which suggests that it has therapeutic potential and safety for use as a painkiller.
目前用于治疗疼痛的药物常常伴有严重的不良反应且耐受性发展迅速。因此，有必要为人们开发更有效、更安全的药物。阻断N-甲基-D-天冬氨酸受体（NMDAR）已显示出是开发新药的一个有前景的靶点。这一说法是因为脊髓中NMDAR的激活和谷氨酸释放会影响慢性疼痛调节。因此，本研究的目的是评估PnTx4(5-5)毒素可能的脊髓抗伤害感受活性。该肽是从蜘蛛毒液中纯化得到的，并且其对NMDAR和钠通道Nav1.2 - 1.6的亲和力已经得到确定。
我们将其效果和安全性与MK - 801（NMDAR拮抗剂）进行了比较，并评估了其对脑脊液中谷氨酸和活性氧（ROS）水平的影响。在福尔马林试验中鞘内注射PnTx4(5-5)，并在自发疼痛试验中与NMDA联合给药。观察三分钟后，收集小鼠脑脊液以测量谷氨酸和ROS水平。
蜘蛛肽在福尔马林试验的炎症期作为后处理抑制了伤害感受。此外，它抑制了由NMDA诱导的自发伤害感受，在两个测试模型中比MK - 801更有效力且更有效。毒素显著降低了小鼠脑脊液中谷氨酸的升高水平，但ROS的增加未受影响。受试剂量的NMDAR抑制剂未影响动物的运动技能。
总之，结果表明PnTx4(5-5)可能不仅通过抑制突触后受体，还可能通过作用于自身受体在脊髓中介导其抗伤害感受作用。这种作用在测试的最高剂量下不影响小鼠的运动能力，这表明它具有作为止痛药使用的治疗潜力和安全性。
