Methylphenidate ameliorates the homeostatic balance between levels of kynurenines in ADHD children Molina Carballo, Antonio Cubero Millán, Isabel Fernández López, Luisa Checa Ros, Ana Machado Casas, Irene Jerez Calero, Antonio Emilio Blanca Jóver, Enrique Cantarero Malagón, Antonio Manuel Uberos Fernández, José Muñoz Hoyos, Antonio ADHD Kynurenines Daily rhythms Children The kynurenine pathway of tryptophan metabolism has been involved in ADHD We quantified basal levels and daily fluctuations of tryptophan and several kynurenine metabolites, as well as their changes after treatment with methylphenidate (MPH). A total of 179 children were recruited, grouped into ADHD (n = 130) and healthy controls (CG,n = 49). Blood samples were drawn at 20:00 and 09:00 h and only in the ADHD group after 4.63±2.3 months of treatment. Nocturnal urine was collected between both draws. Factorial analysis (Stata12.0) was performed with Groups, Time, Hour of Day and Depressive Symptoms (DS) as factors. MPH significantly increased plasma Kynurenic acid (2.4 ± 1.03/2.78±1.3 ng/mL; baseline/post-treatment, morning; z = 1.96,p<0.05) and Xanthurenic acid (2.39±0.95/2.88±1.19 ng/mL; baseline/post, morning; z = 2.7,p<0.007) levels, both with higher values in the evening. In DS+ patients, MPH caused a pronounced decrease in evening Anthranilic acid [3.08±5.02/ 1.82±1.46 ng/mL, z = 2.68,p = 0.0074] until matching values to other subgroups. In urine, MPH decreased the excretion of both Nicotinamide and Quinolinic acids, but only in the DSsubgroup. The kynurenine pathway may participate in the highly clinical favorable response to MPH. The observed changes could be considered as protective (i.e. increased plasma kynurenic acid vs. decreased quinolinic acid excretion) based on the knowledge of its physiological homeostatic functions. 2023-03-07T09:01:02Z 2023-03-07T09:01:02Z 2021-06-17 journal article Antonio Molina-Carballo... [et al.]. Methylphenidate ameliorates the homeostatic balance between levels of kynurenines in ADHD children, Psychiatry Research, Volume 303, 2021, 114060, ISSN 0165-1781, [https://doi.org/10.1016/j.psychres.2021.114060] https://hdl.handle.net/10481/80446 10.1016/j.psychres.2021.114060 eng http://creativecommons.org/licenses/by-nc-nd/4.0/ open access Attribution-NonCommercial-NoDerivatives 4.0 Internacional Elsevier