Tsagareli Merab G, Nozadze Ivliane, Tsiklauri Nana, Gurtskaia Gulnaz
Laboratory of Pain and Analgesia, Beritashvili Center for Experimental Biomedicine, Tbilisi 0160, Georgia.
Med Sci (Basel). 2019 Apr 18;7(4):62. doi: 10.3390/medsci7040062.
Persistent itch (pruritus) accompanying dermatologic and systemic diseases can significantly impair the quality of life. It is well known that itch is broadly categorized as histaminergic (sensitive to antihistamine medications) or non-histaminergic. Sensory neurons expressing Mas-related G-protein-coupled receptors (Mrgprs) mediate histamine-independent itch. These receptors have been shown to bind selective pruritogens in the periphery and mediate non-histaminergic itch. For example, mouse MrgprA3 responds to chloroquine (an anti-malarial drug), and are responsible for relaying chloroquine-induced scratching in mice. Mouse MrgprC11 responds to a different subset of pruritogens including bovine adrenal medulla peptide (BAM8-22) and the peptide Ser-Leu-Ile-Gly-Arg-Leu (SLIGRL). On the other hand, the possibility that itch mediators also influence pain is supported by recent findings that most non-histaminergic itch mediators require the transient receptor potential ankyrin 1 (TRPA1) channel. We have recently found a significant increase of thermal and mechanical hyperalgesia induced by non-histaminergic pruritogens chloroquine and BAM8-22, injected into mice hindpaw, for the first 30-45 min. Pretreatment with TRPA1 channel antagonist HC-030031 did significantly reduce the magnitude of this hyperalgesia, as well as significantly shortened the time-course of hyperalgesia induced by chloroquine and BAM8-22. Here, we report that MrgprC11-mediated itch by their agonist SLIGRL is accompanied by heat and mechanical hyperalgesia via the TRPA1 channel. We measured nociceptive thermal paw withdrawal latencies and mechanical thresholds bilaterally in mice at various time points following intra-plantar injection of SLIGRL producing hyperalgesia. When pretreated with the TRPA1 antagonist HC-030031, we found a significant reduction of thermal and mechanical hyperalgesia.
伴随皮肤病和全身性疾病出现的持续性瘙痒会显著损害生活质量。众所周知,瘙痒大致可分为组胺能性(对抗组胺药物敏感)或非组胺能性。表达Mas相关G蛋白偶联受体(Mrgprs)的感觉神经元介导非组胺依赖性瘙痒。这些受体已被证明在外周与选择性致痒原结合并介导非组胺能性瘙痒。例如,小鼠MrgprA3对氯喹(一种抗疟药物)有反应,并负责传递氯喹诱导的小鼠抓挠行为。小鼠MrgprC11对包括牛肾上腺髓质肽(BAM8 - 22)和肽Ser - Leu - Ile - Gly - Arg - Leu(SLIGRL)在内的另一组不同的致痒原有反应。另一方面,最近的研究结果支持瘙痒介质也会影响疼痛这一可能性,即大多数非组胺能性瘙痒介质需要瞬时受体电位锚蛋白1(TRPA1)通道。我们最近发现,将非组胺能性致痒原氯喹和BAM8 - 22注射到小鼠后爪中,在最初的30 - 45分钟内会导致热痛觉过敏和机械性痛觉过敏显著增加。用TRPA1通道拮抗剂HC - 030031预处理可显著降低这种痛觉过敏的程度,并显著缩短氯喹和BAM8 - 22诱导的痛觉过敏的时间进程。在此,我们报告MrgprC11通过其激动剂SLIGRL介导的瘙痒会通过TRPA1通道伴随热痛觉过敏和机械性痛觉过敏。我们在足底注射产生痛觉过敏的SLIGRL后的不同时间点,双侧测量小鼠的伤害性热爪退缩潜伏期和机械阈值。当用TRPA1拮抗剂HC - 030031预处理时,我们发现热痛觉过敏和机械性痛觉过敏显著减轻。