Wei Hong, Sagalajev Boriss, Yüzer M Anil, Koivisto Ari, Pertovaara Antti
Department of Physiology, Faculty of Medicine, University of Helsinki, Helsinki, Finland.
Orion Pharma, Orion Corporation, Turku, Finland.
Neurosci Lett. 2015 Nov 3;608:12-7. doi: 10.1016/j.neulet.2015.09.033. Epub 2015 Sep 30.
Pain per se may increase anxiety and conversely, anxiety may increase pain. Therefore, a positive feedback loop between anxiety and pain possibly contributes to pain and suffering in some pathophysiological pain conditions, such as that induced by peripheral nerve injury. Recent results indicate that transient receptor channels 4 and 5 (TRPC4/C5) in the amygdala have anxiogenic effects in rodents, while their role in chronic pain conditions is not known. Here, we studied whether the amygdaloid TRPC4/C5 that are known to have anxiogenic properties contribute to the maintenance of sensory or affective aspects of pain in an experimental model of peripheral neuropathy. Rats with a spared nerve injury (SNI) model of neuropathy in the left hind limb had a chronic cannula for microinjections of drugs into the right amygdala or the internal capsule (a control site). Sensory pain was assessed by determining mechanical hypersensitivity with calibrated monofilaments and affective pain by determining aversive place-conditioning. Amygdaloid treatment with ML-204, a TRPC4/C5 antagonist, produced a dose-related (5-10 μg) antihypersensitivity effect, without obvious side-effects. Additionally, amygdaloid administration of ML-204 reduced affective-like pain behavior. In the internal capsule, ML-204 had no effect on hypersensitivity or affective-like pain in SNI animals. In healthy controls, amygdaloid administration of ML-204 failed to influence pain behavior induced by mechanical stimulation or noxious heat. The results indicate that the amygdaloid TRPC4/C5 contribute to maintenance of pain hypersensitivity and pain affect in neuropathy.
疼痛本身可能会加剧焦虑,反之,焦虑也可能加重疼痛。因此,焦虑与疼痛之间的正反馈回路可能在某些病理生理性疼痛状况(如由外周神经损伤引起的疼痛)中导致疼痛和痛苦。最近的研究结果表明,杏仁核中的瞬时受体通道4和5(TRPC4/C5)在啮齿动物中具有致焦虑作用,但其在慢性疼痛状况中的作用尚不清楚。在此,我们研究了已知具有致焦虑特性的杏仁核TRPC4/C5是否在周围神经病变的实验模型中有助于维持疼痛的感觉或情感方面。左后肢患有保留神经损伤(SNI)模型神经病变的大鼠,其右杏仁核或内囊(对照部位)有用于微量注射药物的慢性套管。通过用校准的单丝测定机械性超敏反应来评估感觉性疼痛,通过测定厌恶性位置条件反射来评估情感性疼痛。用TRPC4/C5拮抗剂ML-204对杏仁核进行处理产生了剂量相关(5-10μg)的抗超敏反应作用,且无明显副作用。此外,向杏仁核注射ML-204可减少类情感性疼痛行为。在内囊中,ML-204对SNI动物的超敏反应或类情感性疼痛没有影响。在健康对照中,向杏仁核注射ML-204未能影响由机械刺激或有害热诱导的疼痛行为。结果表明,杏仁核TRPC4/C5有助于维持神经病变中的疼痛超敏反应和疼痛情感。
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