Abstract：
BACKGROUND: Studies present ambiguous findings regarding the role of tryptophan and its metabolites, kynurenine and serotonin in chronic musculoskeletal pain. This systematic review aimed to investigate the expression of tryptophan and its metabolites, serotonin and kynurenine in patients with local and generalized chronic musculoskeletal pain in comparison with pain-free controls.
METHODS: An electronic search was conducted in the databases MEDLINE, CINAHL, EMBASE, the Cochrane Central Registry of Controlled Trials (CENTRAL) and Web of Science for clinical and observational trials from the beginning of each database to 21 April 2023. Out of 6734 articles, a total of 17 studies were included; 12 studies were used in the meta-analysis of serotonin, 3 regarding tryptophan and 2 studies for a narrative synthesis regarding kynurenine. Risk of bias was assessed using the quality assessment tool for observational cohort and cross-sectional studies of the National Heart, Lung, and Blood Institute, while the certainty of evidence was by GRADE.
RESULTS: All included studies showed a low risk of bias. The meta-analysis showed lower blood levels of tryptophan (p < .001; very low quality of evidence) and higher blood levels of serotonin (p < .001; very low-quality evidence) in patients with generalized musculoskeletal pain, when compared to pain-free individuals. In local chronic musculoskeletal pain, there were higher blood levels of serotonin (p=.251; very low quality of evidence) compared to pain-free individuals. Regarding kynurenine, the studies reported both higher and lower blood levels in generalized chronic musculoskeletal pain compared to pain-free individuals.
CONCLUSIONS: The blood levels of tryptophan and its metabolites serotonin and kynurenine seem to influence chronic musculoskeletal pain.
METHODS: An electronic search was conducted in the databases MEDLINE, CINAHL, EMBASE, the Cochrane Central Registry of Controlled Trials (CENTRAL) and Web of Science for clinical and observational trials from the beginning of each database to 21 April 2023. Out of 6734 articles, a total of 17 studies were included; 12 studies were used in the meta-analysis of serotonin, 3 regarding tryptophan and 2 studies for a narrative synthesis regarding kynurenine. Risk of bias was assessed using the quality assessment tool for observational cohort and cross-sectional studies of the National Heart, Lung, and Blood Institute, while the certainty of evidence was by GRADE.
RESULTS: All included studies showed a low risk of bias. The meta-analysis showed lower blood levels of tryptophan (p < .001; very low quality of evidence) and higher blood levels of serotonin (p < .001; very low-quality evidence) in patients with generalized musculoskeletal pain, when compared to pain-free individuals. In local chronic musculoskeletal pain, there were higher blood levels of serotonin (p=.251; very low quality of evidence) compared to pain-free individuals. Regarding kynurenine, the studies reported both higher and lower blood levels in generalized chronic musculoskeletal pain compared to pain-free individuals.
CONCLUSIONS: The blood levels of tryptophan and its metabolites serotonin and kynurenine seem to influence chronic musculoskeletal pain.
摘要：
背景：关于色氨酸及其代谢产物的研究结果含糊不清，犬尿氨酸和5-羟色胺在慢性肌肉骨骼疼痛中的作用。本系统综述旨在研究色氨酸及其代谢产物的表达,与无痛对照组相比，局部和全身慢性肌肉骨骼疼痛患者的5-羟色胺和犬尿氨酸。
方法：在MEDLINE数据库中进行了电子搜索，CINAHL,EMBASE,Cochrane中央对照试验注册中心(CENTRAL)和WebofScience用于从每个数据库开始到2023年4月21日的临床和观察试验.在6734篇文章中，共纳入17项研究；12项研究用于血清素的荟萃分析，关于色氨酸的3项研究和关于犬尿氨酸的叙事合成的2项研究。使用国家心脏观察队列和横断面研究的质量评估工具评估偏倚风险。肺，血液研究所，而证据的确定性是按等级划分的。
结果：所有纳入研究均显示偏倚风险较低。荟萃分析显示，广泛性肌肉骨骼疼痛患者的血液色氨酸水平较低（p<.001；证据质量非常低）和血液5-羟色胺水平较高（p<.001；证据质量非常低），与无痛个体相比。在局部慢性肌肉骨骼疼痛中，与无痛个体相比,血5-羟色胺水平较高(p=.251;证据质量非常低).关于犬尿氨酸,研究报告,与无痛个体相比,广泛性慢性肌肉骨骼疼痛患者的血液水平较高和较低.
结论：色氨酸及其代谢物5-羟色胺和犬尿氨酸的血液水平似乎影响慢性肌肉骨骼疼痛。
方法：在MEDLINE数据库中进行了电子搜索，CINAHL,EMBASE,Cochrane中央对照试验注册中心(CENTRAL)和WebofScience用于从每个数据库开始到2023年4月21日的临床和观察试验.在6734篇文章中，共纳入17项研究；12项研究用于血清素的荟萃分析，关于色氨酸的3项研究和关于犬尿氨酸的叙事合成的2项研究。使用国家心脏观察队列和横断面研究的质量评估工具评估偏倚风险。肺，血液研究所，而证据的确定性是按等级划分的。
结果：所有纳入研究均显示偏倚风险较低。荟萃分析显示，广泛性肌肉骨骼疼痛患者的血液色氨酸水平较低（p<.001；证据质量非常低）和血液5-羟色胺水平较高（p<.001；证据质量非常低），与无痛个体相比。在局部慢性肌肉骨骼疼痛中，与无痛个体相比,血5-羟色胺水平较高(p=.251;证据质量非常低).关于犬尿氨酸,研究报告,与无痛个体相比,广泛性慢性肌肉骨骼疼痛患者的血液水平较高和较低.
结论：色氨酸及其代谢物5-羟色胺和犬尿氨酸的血液水平似乎影响慢性肌肉骨骼疼痛。
