The effect of a beta(2)-adrenergic agonist, clenbuterol on the production of a glutamate receptor antagonist, kynurenic acid was studied in vitro. Clenbuterol enhanced the production of kynurenic acid in brain cortical slices (0.1-1.0 mM) and in glial cultures (1-50 muM). Timolol, a non-selective beta-adrenergic antagonist prevented this effect. The presented data indicate a novel mechanism of action of beta(2)-adrenoceptor agonists and suggest that an increased formation of the endogenous glutamate receptor antagonist, kynurenic acid could partially contribute to their neuroprotective activity.
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PLoS One
January 2025
Department of Clinical Physiology, Karolinska University Hospital, Stockholm, Sweden.
Background: The causes of reduced aerobic exercise capacity (ExCap) in chronic kidney disease (CKD) are multifactorial, possibly involving the accumulation of tryptophan (TRP) metabolites such as kynurenine (KYN) and kynurenic acid (KYNA), known as kynurenines. Their relationship to ExCap has yet to be studied in CKD. We hypothesised that aerobic ExCap would be negatively associated with plasma levels of TRP, KYN and KYNA in CKD.
View Article and Find Full Text PDFAm J Physiol Endocrinol Metab
January 2025
Molecular and Cellular Exercise Physiology, Department of physiology and Pharmacology, Karolinska Institutet, Stockholm, Sweden.
Kynurenic acid (KYNA) and quinolinic acid (QUIN) are metabolites of the kynurenine pathway of tryptophan degradation with opposing biological activities in the central nervous system. In the periphery, KYNA is known to positively affect metabolic health, whereas the effects of QUIN remain less explored. Interestingly, metabolic stressors, including exercise and obesity, differentially change the balance between circulating KYNA and QUIN.
View Article and Find Full Text PDFMolecules
December 2024
Department of Physical Pharmacy and Pharmacokinetics, Poznan University of Medical Sciences, 3 Rokietnicka Street, 60-806 Poznań, Poland.
Tryptophan (TRP) is an essential amino acid crucial for the production of many bioactive compounds. Disturbances in TRP metabolism have been revealed in various diseases, many of which are closely related to the immune system. In recent years, we have focused on finding blood-based biomarkers of successful immunotherapy in cancer.
View Article and Find Full Text PDFCells
January 2025
Research Institute of Medical and Health Sciences, University of Sharjah, Sharjah P.O. Box 27272, United Arab Emirates.
The Kynurenine pathway is crucial in metabolizing dietary tryptophan into bioactive compounds known as kynurenines, which have been linked to glucose homeostasis. The aryl hydrocarbon receptor (AhR) has recently emerged as the endogenous receptor for the kynurenine metabolite, kynurenic acid (KYNA). However, the specific role of AhR in pancreatic β-cells remains largely unexplored.
View Article and Find Full Text PDFBMC Endocr Disord
January 2025
School of Public Health, Anhui Medical University, No. 81 Meishan Road, Hefei, Anhui, 230032, China.
Background: As the prevalence of metabolic syndrome (MetS) rises among older adults, the associated risks of cardiovascular diseases and diabetes significantly increase, and it is closely linked to various metabolic processes in the body. Dysregulation of tryptophan (TRP) metabolism, particularly alterations in the kynurenine (KYN) and serotonin pathways, has been linked to the onset of chronic inflammation, oxidative stress, and insulin resistance, key contributors to the development of MetS. We aim to investigate the relationship between the TRP metabolites and the risk of MetS in older adults.
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