Department of Physiotherapy, Universidade Federal de Juiz de Fora, Governador Valadares 35020-360, MG, Brazil.
Instituto Rene Rachou-Fiocurz Minas, Belo Horizonte 30190-009, MG, Brazil.
Cells. 2024 Oct 3;13(19):1647. doi: 10.3390/cells13191647.
Though the mechanisms are not fully understood, tryptophan (Trp) and physical exercise seem to regulate mechanical hypersensitivity in fibromyalgia. Here, we tested the impact of Trp supplementation and continuous low-intensity aerobic exercise on the modulation of mechanical hypersensitivity in a fibromyalgia-like model induced by acid saline in female rats. Twelve-month-old female Wistar rats were randomly divided into groups: [control (n = 6); acid saline (n = 6); acid saline + exercise (n = 6); acid saline + Trp (n = 6); and acid saline + exercise + Trp (n = 6)]. Hypersensitivity was caused using two intramuscular jabs of acid saline (20 μL; pH 4.0; right gastrocnemius), 3 days apart. The tryptophan-supplemented diet contained 7.6 g/hg of Trp. The three-week exercise consisted of progressive (30-45 min) treadmill running at 50 to 60% intensity, five times (Monday to Friday) per week. We found that acid saline induced contralateral mechanical hypersensitivity without changing the levels of Trp, serotonin (5-HT), and kynurenine (KYN) in the brain. Hypersensitivity was reduced by exercise (150%), Trp (67%), and its combination (~160%). The Trp supplementation increased the levels of Trp and KYN in the brain, and the activity of indoleamine 2,3-dioxygenase (IDO), and decreased the ratio 5-HT:KYN. Exercise did not impact the assessed metabolites. Combining the treatments reduced neither hypersensitivity nor the levels of serotonin and Trp in the brain. In conclusion, mechanical hypersensitivity induced by acid saline in a fibromyalgia-like model in female rats is modulated by Trp supplementation, which increases IDO activity and leads to improved Trp metabolism via the KYN pathway. In contrast, physical exercise does not affect mechanical hypersensitivity through brain Trp metabolism via either the KYN or serotonin pathways. Because this is a short study, generalizing its findings warrants caution.
虽然机制尚不完全清楚，但色氨酸（Trp）和体育锻炼似乎可以调节纤维肌痛症的机械性超敏反应。在这里，我们测试了色氨酸补充和连续低强度有氧运动对雌性大鼠酸性生理盐水诱导的纤维肌痛样模型中机械性超敏反应的调节作用。将 12 个月大的雌性 Wistar 大鼠随机分为以下几组：[对照组（n=6）；酸性生理盐水组（n=6）；酸性生理盐水+运动组（n=6）；酸性生理盐水+色氨酸组（n=6）；和酸性生理盐水+运动+色氨酸组（n=6）]。通过相隔 3 天的两次右腓肠肌肌内注射酸性生理盐水（20 μL；pH 值 4.0）引起超敏反应。色氨酸补充饮食包含 7.6 g/hg 的色氨酸。为期 3 周的运动包括逐渐增加（30-45 分钟）的跑步机跑步，强度为 50-60%，每周 5 次（周一至周五）。我们发现，酸性生理盐水诱导了对侧机械性超敏反应，而大脑中的色氨酸、血清素（5-HT）和犬尿氨酸（KYN）水平没有改变。运动（150%）、色氨酸（67%）及其组合（~160%）可降低超敏反应。色氨酸补充增加了大脑中的色氨酸和 KYN 水平，以及吲哚胺 2,3-双加氧酶（IDO）的活性，降低了 5-HT:KYN 的比值。运动没有影响评估的代谢物。联合治疗既没有降低超敏反应，也没有降低大脑中 5-HT 和色氨酸的水平。总之，雌性大鼠纤维肌痛样模型中酸性生理盐水诱导的机械性超敏反应是由色氨酸补充调节的，它增加了 IDO 的活性，并通过 KYN 途径改善了色氨酸的代谢。相比之下，体育锻炼并没有通过 KYN 或 5-HT 途径影响大脑中色氨酸代谢的机械性超敏反应。由于这是一项短期研究，因此谨慎推广其发现是必要的。
