{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,4,20]],"date-time":"2026-04-20T11:05:47Z","timestamp":1776683147868,"version":"3.51.2"},"reference-count":82,"publisher":"MDPI AG","issue":"4","license":[{"start":{"date-parts":[[2026,4,18]],"date-time":"2026-04-18T00:00:00Z","timestamp":1776470400000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"the Austrian NFB Life Science","award":["LS10-032"],"award-info":[{"award-number":["LS10-032"]}]},{"name":"Department of Science and Research of the Government of Lower Austria","award":["K3-F-995\/001-2021"],"award-info":[{"award-number":["K3-F-995\/001-2021"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Biomolecules"],"abstract":"<jats:p>Kynurenic acid (KYNA), a metabolite of the L-kynurenine pathway of L-tryptophan degradation, is an endogenous blocker of glutamate ionotropic excitatory amino acid (EAA) receptors and nicotinic acetylcholine receptors (nAChRs). KYNA plays a significant role in various neuropsychiatric disorders and the aging process. Some researchers have suggested that KYNA may contribute to memory impairment. In this study, we examined the impact of L-kynurenine (a KYNA substrate) and the anti-dementia drugs D-cycloserine and Cerebrolysin on kynurenine aminotransferase (KAT) activity, an enzyme forming KYNA, in liver homogenates of Helix pomatia snails. Furthermore, a memory model was established using these snails, wherein tentacle shortening served as an indicator of learning activity. In vitro experiments on Helix pomatia demonstrated the significant impact of L-kynurenine and anti-dementia drugs on KYNA synthesis. KYNA levels increased significantly in the presence of L-kynurenine in liver homogenate. However, KYNA formation decreased when anti-dementia drugs, including Cerebrolysin or D-cycloserine, were administered to the snails\u2019 liver homogenate. L-kynurenine has been shown to impair the learning process in vivo in snails, but an anti-dementia drug has been demonstrated to reverse this effect. Significant inhibition of tentacle lowering was observed in response to L-kynurenine treatment, which corresponded with elevated KYNA levels in the central nervous system. Administering D-cycloserine or Cerebrolysin alongside L-kynurenine reversed its effects. The Helix pomatia memory model is a valuable tool for studying learning and memory formation in various conditions and in the presence of different pharmacological agents. A drug or natural extract that blocks KYNA synthesis has the ability to increase tentacle lowering and could be considered an anti-dementia agent. Furthermore, this metabolite may also protect against aging and delay damage to the central nervous system related to memory.<\/jats:p>","DOI":"10.3390\/biom16040603","type":"journal-article","created":{"date-parts":[[2026,4,20]],"date-time":"2026-04-20T09:37:42Z","timestamp":1776677862000},"page":"603","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["Biochemical and Pharmacological Studies on Kynurenic Acid Metabolism in the Helix pomatia\u2014Snail Model of Learning and Memory"],"prefix":"10.3390","volume":"16","author":[{"ORCID":"https:\/\/orcid.org\/0000-0001-6236-4019","authenticated-orcid":false,"given":"Halina","family":"Baran","sequence":"first","affiliation":[{"name":"Karl Landsteiner Research Institute for Neurochemistry, Neuropharmacology, Neurorehabilitation and Pain Treatment Mauer, Neuropsychiatric Hospital Mauer, Hausmenninger Stra\u00dfe 221, 3362 Mauer bei Amstetten, Austria"},{"name":"Department of Biomedical Sciences, University of Veterinary Medicine Vienna, 1210 Vienna, Austria"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Carina","family":"Kronsteiner","sequence":"additional","affiliation":[{"name":"Karl Landsteiner Research Institute for Neurochemistry, Neuropharmacology, Neurorehabilitation and Pain Treatment Mauer, Neuropsychiatric Hospital Mauer, Hausmenninger Stra\u00dfe 221, 3362 Mauer bei Amstetten, Austria"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1968","published-online":{"date-parts":[[2026,4,18]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"165","DOI":"10.1007\/s007020050149","article-title":"Kynurenine metabolism in Alzheimer\u2019s disease","volume":"106","author":"Baran","year":"1999","journal-title":"J. Neural Transm."},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"769","DOI":"10.1093\/schbul\/sbq151","article-title":"Exposure to kynurenic acid during adolescence produces memory deficits in adulthood","volume":"38","author":"Akagbosu","year":"2012","journal-title":"Schizophr. Bull."},{"key":"ref_3","doi-asserted-by":"crossref","unstructured":"DeAngeli, N.E., Todd, T.P., Chang, S.E., Yeh, H.H., Yeh, P.W., and Bucci, D.J. (2015). Exposure to kynurenic acid during adolescence increases sign-tracking and impairs long-term potentiation in adulthood. Front. Behav. Neurosci., 8.","DOI":"10.3389\/fnbeh.2014.00451"},{"key":"ref_4","doi-asserted-by":"crossref","unstructured":"Gonz\u00e1lez-S\u00e1nchez, M., Jim\u00e9nez, J., Narv\u00e1ez, A., Antequera, D., Llamas-Velasco, S., Mart\u00edn, A.H.-S., Molina Arjona, J.A., L\u00f3pez de Munain, A., Lle\u00f3 Bisa, A., and Marco, M.-P. (2020). Kynurenic Acid Levels are Increased in the CSF of Alzheimer\u2019s Disease Patients. Biomolecules, 10.","DOI":"10.3390\/biom10040571"},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"5573","DOI":"10.1002\/alz.13162","article-title":"Higher concentrations of kynurenic acid in CSF are associated with the slower clinical progression of Alzheimer\u2019s disease","volume":"19","author":"Knapskog","year":"2023","journal-title":"Alzheimer\u2019s Dement."},{"key":"ref_6","first-page":"286","article-title":"The kynurenine pathway in Alzheimer\u2019s disease: A meta-analysis of central and peripheral levels","volume":"45","author":"Fernandes","year":"2023","journal-title":"Braz. J. Psychiatry"},{"key":"ref_7","doi-asserted-by":"crossref","unstructured":"Choe, K., Bakker, L., van den Hove, D.L.A., Eussen, S.J.P.M., Kenis, G., Ramakers, I.H.G.B., Verhey, F.R.J., Rutten, B.P.F., and K\u00f6hler, S. (2025). Kynurenine pathway dysregulation in cognitive impairment and dementia: A systematic review and meta-analysis. GeroScience, 1\u201335.","DOI":"10.1007\/s11357-025-01636-3"},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"797","DOI":"10.1093\/schbul\/sbl033","article-title":"Elevations of kynurenic acid produce working memory deficits","volume":"33","author":"Chess","year":"2007","journal-title":"Schizophr. Bull."},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"10592","DOI":"10.1523\/JNEUROSCI.1107-14.2014","article-title":"Reduction of brain kynurenic acid improves cognitive function","volume":"34","author":"Kozak","year":"2014","journal-title":"J. Neurosci."},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"19","DOI":"10.1111\/cns.13768","article-title":"Kynurenic acid in neurodegenerative disorders\u2014Unique neuroprotection or double- edged sword?","volume":"28","author":"Ostapiuk","year":"2022","journal-title":"CNS Neurosci. Ther."},{"key":"ref_11","doi-asserted-by":"crossref","unstructured":"Martos, D., Tuka, B., Tanaka, M., V\u00e9csei, L., and Telegdy, G. (2022). Memory enhancement with kynurenic acid and its mechanisms in neurotransmission. Biomedicines, 10.","DOI":"10.20944\/preprints202203.0327.v1"},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"308","DOI":"10.1016\/j.neuint.2006.08.012","article-title":"Decreased serum and red blood cell kynurenic acid levels in Alzheimer\u2019s disease","volume":"50","author":"Hartai","year":"2007","journal-title":"Neurochem. Int."},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"204","DOI":"10.2478\/v10039-010-0023-6","article-title":"Kynurenine and its metabolites in Alzheimer\u2019s disease patients","volume":"55","author":"Gulaj","year":"2010","journal-title":"Adv. Med. Sci."},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"863","DOI":"10.1016\/j.cell.2011.05.020","article-title":"Kynurenine 3-monooxygenase inhibition in blood ameliorates neurodegeneration","volume":"10","author":"Zwilling","year":"2011","journal-title":"Cell"},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"309","DOI":"10.1016\/S0031-6997(25)00441-7","article-title":"Neuropharmacology of quinolinic and kynurenic acids","volume":"45","author":"Stone","year":"1993","journal-title":"Pharmacol. Rev."},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"85","DOI":"10.1016\/0014-2999(88)90367-6","article-title":"Kynurenic acid antagonizes responses to NMDA via an action at the strychnine-insensitive glycine receptor","volume":"154","author":"Birch","year":"1988","journal-title":"Eur. J. Pharmacol."},{"key":"ref_17","doi-asserted-by":"crossref","first-page":"7463","DOI":"10.1523\/JNEUROSCI.21-19-07463.2001","article-title":"The brain metabolite kynurenic acid inhibits alpha7 nicotinic receptor activity and increases non-alpha7 nicotinic receptor expression: Physiopathological implications","volume":"21","author":"Hilmas","year":"2001","journal-title":"J. Neurosci."},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"22021","DOI":"10.1074\/jbc.M603503200","article-title":"Kynurenic acid as a ligand for orphan G protein-coupled receptor GPR35","volume":"281","author":"Wang","year":"2006","journal-title":"Biol. J. Chem."},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"136","DOI":"10.1016\/j.tips.2012.09.006","article-title":"An Expanding range of targets for kynurenine metabolism of tryptophan","volume":"34","author":"Stone","year":"2013","journal-title":"Trends Pharmacol. Sci."},{"key":"ref_20","doi-asserted-by":"crossref","first-page":"273","DOI":"10.1016\/0304-3940(84)90050-8","article-title":"Kynurenic acid blocks neurotoxicity and seizures induced in rats by the related brain metabolite quinolinic acid","volume":"48","author":"Foster","year":"1984","journal-title":"Neurosci. Lett."},{"key":"ref_21","doi-asserted-by":"crossref","unstructured":"Bratek-Gerej, E., Ziembowicz, A., Godlewski, J., and Salinska, E. (2021). The Mechanism of the neuroprotective effect of kynurenic acid in the experimental model of neonatal hypoxia\u2013ischemia: The link to oxidative stress. Antioxidants, 10.","DOI":"10.3390\/antiox10111775"},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"1117","DOI":"10.1016\/S0022-3565(24)36503-6","article-title":"Properties of neuronal nicotinic acetylcholine receptors: Pharmacological characterization and modulation of synaptic function","volume":"280","author":"Albuquerque","year":"1997","journal-title":"J. Pharmacol. Exp. Ther."},{"key":"ref_23","doi-asserted-by":"crossref","first-page":"73","DOI":"10.1152\/physrev.00015.2008","article-title":"Mammalian nicotinic receptors: From structure to function","volume":"89","author":"Albuquerque","year":"2009","journal-title":"Physiol. Rev."},{"key":"ref_24","doi-asserted-by":"crossref","first-page":"421","DOI":"10.1016\/0278-5846(88)90102-9","article-title":"Glutamate transmission and toxicity in Alzheimer\u2019s disease","volume":"12","author":"Greenamyre","year":"1988","journal-title":"Prog. Neuropsychopharmacol. Biol. Psychiatry"},{"key":"ref_25","doi-asserted-by":"crossref","unstructured":"Baran, H., Jan Pietryja, M., and Kepplinger, B. (2025). Importance of modulating kynurenic acid metabolism\u2014Approaches for the treatment of dementia. Biomolecules, 15.","DOI":"10.3390\/biom15010074"},{"key":"ref_26","doi-asserted-by":"crossref","first-page":"126","DOI":"10.1159\/000086295","article-title":"Age-related increase of kynurenic acid in human cerebrospinal fluid: Positive correlation with IgG and beta2-microglobulin changes","volume":"14","author":"Kepplinger","year":"2005","journal-title":"Neurosignals"},{"key":"ref_27","doi-asserted-by":"crossref","first-page":"627","DOI":"10.1111\/jnc.14907","article-title":"Does Kynurenic Acid Act on Nicotinic Receptors? An Assessment of the Evidence","volume":"152","author":"Stone","year":"2020","journal-title":"J. Neurochem."},{"key":"ref_28","doi-asserted-by":"crossref","first-page":"567","DOI":"10.1007\/978-1-4684-5952-4_68","article-title":"Kynurenine-pyruvate Aminotransferase in Rat Kidney and Brain","volume":"294","author":"Ishikawa","year":"1991","journal-title":"Adv. Exp. Med. Biol."},{"key":"ref_29","doi-asserted-by":"crossref","first-page":"201","DOI":"10.1007\/978-1-4684-5952-4_18","article-title":"Kynurenate Forming Enzymes in Liver, Kidney and Brain. Kynurenine and Serotonin Pathways","volume":"294","author":"Kido","year":"1991","journal-title":"Adv. Exp. Med. Biol."},{"key":"ref_30","doi-asserted-by":"crossref","first-page":"307","DOI":"10.1016\/0006-8993(91)91583-M","article-title":"Two kynurenine aminotransferases in human brain","volume":"542","author":"Okuno","year":"1991","journal-title":"Brain Res."},{"key":"ref_31","doi-asserted-by":"crossref","first-page":"161","DOI":"10.1016\/j.euroneuro.2008.09.003","article-title":"Cerebrolysin Lowers Kynurenic Acid Formation\u2014An In Vitro Study","volume":"19","author":"Baran","year":"2009","journal-title":"Eur. Neuropsychopharmacol."},{"key":"ref_32","doi-asserted-by":"crossref","first-page":"639","DOI":"10.1016\/j.euroneuro.2013.10.006","article-title":"D-Cycloserine Lowers Kynurenic Acid Formation\u2014New Mechanism of action","volume":"24","author":"Baran","year":"2014","journal-title":"Eur. Neuropsychopharmacol."},{"key":"ref_33","doi-asserted-by":"crossref","first-page":"36","DOI":"10.1016\/S1353-8020(07)70122-0","article-title":"P13 Porcine tissues influence kynurenic acid formation","volume":"12","author":"Baran","year":"2006","journal-title":"Park. Relat. Disord."},{"key":"ref_34","doi-asserted-by":"crossref","first-page":"224","DOI":"10.4172\/2573-4555.1000224","article-title":"Jerusalem Balsam Lowers Kynurenic Acid Formation: An In Vitro Study","volume":"6","author":"Baran","year":"2017","journal-title":"J. Tradit. Med. Clin. Naturopat."},{"key":"ref_35","unstructured":"Kepplinger, B., Kronsteiner, C., Wi\u0119cek, M., and Baran, H. (2017, January 24\u201326). Hawthorn berry extract lowers kynurenic acid and anthranilic acid formation. Proceedings of the 15th ANA-Meeting at the IST Austria, Klosterneuburg, Austria."},{"key":"ref_36","doi-asserted-by":"crossref","unstructured":"Vohra, M., Lemieux, G.A., Lin, L., and Ashrafi, K. (2017). The beneficial effects of dietary restriction on learning are distinct from its effects on longevity and mediated by depletion of a neuroinhibitory metabolite. PLoS Biol., 15.","DOI":"10.1371\/journal.pbio.2002032"},{"key":"ref_37","doi-asserted-by":"crossref","first-page":"1734","DOI":"10.1038\/npp.2010.39","article-title":"Reduction of endogenous kynurenic acid formation enhances extracellular glutamate, hippocampal plasticity, and cognitive behavior","volume":"35","author":"Potter","year":"2010","journal-title":"Neuropsychopharmacology"},{"key":"ref_38","doi-asserted-by":"crossref","first-page":"885","DOI":"10.1111\/jpn.12851","article-title":"Is the consumption of snail meat actually healthy? An analysis of the osteotropic influence of snail meat as a sole source of protein in growing rats","volume":"102","author":"Radzki","year":"2018","journal-title":"J. Anim. Physiol. Anim. Nutr."},{"key":"ref_39","doi-asserted-by":"crossref","first-page":"34","DOI":"10.3758\/s13420-011-0042-6","article-title":"Associative learning phenomena in the snail (Helix aspersa): Conditioned inhibition","volume":"40","author":"Acebes","year":"2012","journal-title":"Learn. Behav."},{"key":"ref_40","doi-asserted-by":"crossref","first-page":"229","DOI":"10.1101\/lm.70704","article-title":"Pavlovian Conditioning of Hermissenda: Current Cellular, Molecular, and Circuit","volume":"11","author":"Crow","year":"2004","journal-title":"Learn. Mem."},{"key":"ref_41","doi-asserted-by":"crossref","first-page":"97","DOI":"10.1016\/S0376-6357(01)00136-X","article-title":"Dissociation of food-finding and tentacle-lowering, following food-attraction conditioning in the snail, Helix aspersa","volume":"53","author":"Ungless","year":"2001","journal-title":"Behav. Process."},{"key":"ref_42","doi-asserted-by":"crossref","first-page":"1517","DOI":"10.1007\/s10071-022-01632-6","article-title":"Context specificity of latent inhibition in the snail Cornu aspersum","volume":"25","author":"Loy","year":"2022","journal-title":"Anim Cogn."},{"key":"ref_43","first-page":"279","article-title":"Kynurenic acid levels and kynurenine aminotransferase I, II and III activities in ganglia, heart and liver of snail Helix pomatia","volume":"18","author":"Kronsteiner","year":"2023","journal-title":"Cell Physiol. Biochem."},{"key":"ref_44","doi-asserted-by":"crossref","first-page":"177","DOI":"10.1111\/j.1471-4159.1988.tb04852.x","article-title":"Presence of kynurenic acid in the mammalian brain","volume":"51","author":"Moroni","year":"1988","journal-title":"J. Neurochem."},{"key":"ref_45","doi-asserted-by":"crossref","first-page":"2007","DOI":"10.1111\/j.1471-4159.1991.tb03460.x","article-title":"Blood-brain barrier transport of kynurenines: Implications for brain synthesis and metabolism","volume":"56","author":"Fukui","year":"1991","journal-title":"J. Neurochem."},{"key":"ref_46","doi-asserted-by":"crossref","first-page":"1629","DOI":"10.1111\/j.1471-4159.1989.tb09218.x","article-title":"Rat brain slices produce and liberate kynurenic acid upon expose to L-kynurenine","volume":"52","author":"Turski","year":"1989","journal-title":"J. Neurochem."},{"key":"ref_47","doi-asserted-by":"crossref","first-page":"363","DOI":"10.1016\/0003-2697(90)90309-W","article-title":"Measurement of Kynurenic Acid in Mammalian Brain Extracts and Cerebrospinal Fluid by High-performance Liquid Chromatography with Fluorometric and Coulometric Electrode Array Detection","volume":"185","author":"Swartz","year":"1990","journal-title":"Anal. Biochem."},{"key":"ref_48","doi-asserted-by":"crossref","first-page":"936","DOI":"10.1093\/schbul\/sbs012","article-title":"D-Cycloserine: An evolving role in learning and neuroplasicity in Schizophrenia","volume":"38","author":"Goff","year":"2012","journal-title":"Schizophr. Bull."},{"key":"ref_49","first-page":"1","article-title":"Kynurenine aminotransferases I, II and III are present in saliva","volume":"28","author":"Baran","year":"2020","journal-title":"Neurosignals"},{"key":"ref_50","doi-asserted-by":"crossref","first-page":"15","DOI":"10.3758\/BF03199158","article-title":"A Pavlovian analysis of food-attraction conditioning in the snail Helix aspersa","volume":"26","author":"Ungless","year":"1998","journal-title":"Anim. Learn. Behav."},{"key":"ref_51","doi-asserted-by":"crossref","first-page":"1315","DOI":"10.1080\/17470210802483545","article-title":"Blocking of conditioning of tentacle lowering in the snail (Helix asparsa)","volume":"62","author":"Acebes","year":"2009","journal-title":"Q. J. Exp. Psychol."},{"key":"ref_52","doi-asserted-by":"crossref","first-page":"958","DOI":"10.1111\/j.1471-4159.1989.tb02552.x","article-title":"Increase in kynurenic acid in Huntington\u2019s disease motor cortex","volume":"52","author":"Connick","year":"1989","journal-title":"J. Neurochem."},{"key":"ref_53","doi-asserted-by":"crossref","first-page":"1163","DOI":"10.1002\/mds.22953","article-title":"Cognitive and functional decline in Huntington\u2019s disease: Dementia criteria revisited","volume":"25","author":"Peavy","year":"2010","journal-title":"Mov. Disord."},{"key":"ref_54","doi-asserted-by":"crossref","first-page":"1249","DOI":"10.1016\/S0024-3205(01)01215-2","article-title":"Increased kynurenic acid in the brain after neonatal asphyxia","volume":"69","author":"Baran","year":"2001","journal-title":"Life Sci."},{"key":"ref_55","doi-asserted-by":"crossref","first-page":"167","DOI":"10.1016\/0014-2999(95)00443-O","article-title":"Systemic administration of kainate induces marked increase of endogenous kynurenic acid in various brain regions and plasma of rats","volume":"286","author":"Baran","year":"1995","journal-title":"Eur. J. Pharmacol."},{"key":"ref_56","doi-asserted-by":"crossref","first-page":"147","DOI":"10.1016\/j.ejphar.2006.05.015","article-title":"Enhancement of brain kynurenic acid production by anticonvulsants\u2014Novel mechanism of antiepileptic activity?","volume":"541","author":"Kocki","year":"2006","journal-title":"Eur. J. Pharmacol."},{"key":"ref_57","doi-asserted-by":"crossref","first-page":"27","DOI":"10.1006\/phrs.1996.0116","article-title":"Diazepam\u2014Its effects on the development of Pentylenetetrazol kindling, related learning impairments, and neurological cell loss","volume":"35","author":"Becker","year":"1997","journal-title":"Pharmacol. Res."},{"key":"ref_58","doi-asserted-by":"crossref","first-page":"101","DOI":"10.1002\/hup.747","article-title":"Diazepam-induced prospective memory impairment and its relation to retrospective memory, attention, and arousal","volume":"21","author":"Rich","year":"2005","journal-title":"Hum. Psychopharmacol. Clin. Exp."},{"key":"ref_59","first-page":"315","article-title":"Oral Cerebrolysin enhances brain alpha activity and improves cognitive performance in elderly control subjects","volume":"59","author":"Lombardi","year":"2000","journal-title":"J. Neural Transm."},{"key":"ref_60","first-page":"271","article-title":"Positive effects of Cerebrolysin on electroencephalogram slowing, cognition and clinical outcome in patients with postacute traumatic brain injury: An exploratory study","volume":"18","author":"Sampedro","year":"2003","journal-title":"Int. Clin. Psychopharmacol."},{"key":"ref_61","first-page":"281","article-title":"Cerebrolysin reduces microglia activation in vivo and in vitro: A potential mechanism of neuroprotection","volume":"59","author":"Lombardi","year":"2000","journal-title":"J. Neural Transm."},{"key":"ref_62","doi-asserted-by":"crossref","first-page":"32","DOI":"10.4103\/0973-7847.65324","article-title":"Hawthorn (Crataegus spp.) in the treatment of cardiovascular disease","volume":"4","author":"Tassell","year":"2010","journal-title":"Pharmacogn. Rev."},{"key":"ref_63","doi-asserted-by":"crossref","first-page":"21","DOI":"10.2174\/1570159X14666160225154812","article-title":"D-cycloserine in Schizophrenia: New Strategies for Improving Clinical Outcomes by Enhancing Plasticity","volume":"15","author":"Goff","year":"2017","journal-title":"Curr. Neuropharmacol."},{"key":"ref_64","first-page":"1059","article-title":"Anthranilic acid: A potential biomarker and treatment target for schizophrenia","volume":"4","author":"Oxenkrug","year":"2016","journal-title":"Ann. Psychiatry Ment. Health"},{"key":"ref_65","doi-asserted-by":"crossref","first-page":"128","DOI":"10.4172\/2376-0281.1000128","article-title":"Stroke Patients after repetitive Transcranial Magnetic Stimulation (rTMS) \u2013Alterations of Tryptophan Metabolites in the Serum","volume":"1","author":"Kepplinger","year":"2014","journal-title":"Int. J. Neurorehabilit."},{"key":"ref_66","doi-asserted-by":"crossref","first-page":"49","DOI":"10.4137\/IJTR.S7986","article-title":"Stochastic resonance activity influences serum tryptophan metabolism in healthy human subjects","volume":"4","author":"Kepplinger","year":"2011","journal-title":"Int. J. Tryptophan Res."},{"key":"ref_67","first-page":"17","article-title":"Effects of various kynurenine metabolites on respiratory parameters of rat brain, liver and heart mitochondria","volume":"9","author":"Baran","year":"2016","journal-title":"Int. J. Tryptophan Res."},{"key":"ref_68","unstructured":"Kepplinger, B., Baran, H., Staniek, K., Bertignol, M., Attam, M., and Sedlnitzky-Semler, B. (2010, January 13\u201317). Age-related alterations of kynurenine aminotransferase I, II and III activities. Proceedings of the Annual Meeting of the Society for Neuroscience, San Diego, CA, USA."},{"key":"ref_69","doi-asserted-by":"crossref","first-page":"16","DOI":"10.1186\/1742-2094-2-16","article-title":"Quinolinic acid selectively induces apoptosis of human astrocytes: Potential role in AIDS dementia complex","volume":"26","author":"Guillemin","year":"2005","journal-title":"J. Neuroinflamm."},{"key":"ref_70","first-page":"171","article-title":"HIV-related dementia: Pathology and possible pathogenesis","volume":"Volume 7","author":"Scaravilli","year":"1993","journal-title":"The Neurophatology of HIV Infection"},{"key":"ref_71","doi-asserted-by":"crossref","first-page":"71","DOI":"10.1016\/0165-5728(92)90214-6","article-title":"Inter-relationships between quinolinic acid, neuroactive kynurenines, neopterin and beta2-microglobulin in cerebrospinal fluid and serum of HIV-1-infected patients","volume":"40","author":"Heyes","year":"1992","journal-title":"J. Neuroimmunol."},{"key":"ref_72","doi-asserted-by":"crossref","first-page":"1127","DOI":"10.1007\/s007020070026","article-title":"Kynurenic acid metabolism in the brain of HIV-1 infected patients","volume":"107","author":"Baran","year":"2000","journal-title":"J. Neural Transm."},{"key":"ref_73","doi-asserted-by":"crossref","first-page":"49","DOI":"10.4137\/IJTR.S10627","article-title":"Kynurenic acid metabolism in various types of brain pathology in HIV-1 infected patients","volume":"5","author":"Baran","year":"2012","journal-title":"Int. J. Tryptophan Res."},{"key":"ref_74","doi-asserted-by":"crossref","first-page":"195","DOI":"10.1016\/0006-8993(94)90227-5","article-title":"The glycine\/NMDA receptor partial agonist D-cycloserine blocks kainate-induced seizures in rats. Comparison with MK-801 and diazepam","volume":"652","author":"Baran","year":"1994","journal-title":"Brain Res."},{"key":"ref_75","doi-asserted-by":"crossref","first-page":"217","DOI":"10.1016\/0014-2999(94)90132-5","article-title":"Effect of the glycine\/NMDA receptor partial agonist, D-cycloserine, on seizure threshold and some pharmacodynamic effects of MK-801 in mice","volume":"257","author":"Baran","year":"1994","journal-title":"Eur. J. Pharmacol."},{"key":"ref_76","doi-asserted-by":"crossref","first-page":"2","DOI":"10.1187\/cbe.17-01-0005","article-title":"Approaches to Biology Teaching and Learning Teaching as Brain Changing: Exploring Connections between Neuroscience and Innovative Teaching","volume":"16","author":"Owens","year":"2017","journal-title":"CBE\u2014Life Sci. Educ."},{"key":"ref_77","doi-asserted-by":"crossref","first-page":"426","DOI":"10.1177\/1073858413504465","article-title":"Glial Biology in Learning and Cognition","volume":"20","author":"Fields","year":"2014","journal-title":"Neuroscientist"},{"key":"ref_78","doi-asserted-by":"crossref","first-page":"2015","DOI":"10.1016\/j.neuron.2015.01.014","article-title":"Glial Regulation of the Neuronal Connectome through Local and Long-Distant Communication","volume":"86","author":"Fields","year":"2015","journal-title":"Neuron"},{"key":"ref_79","doi-asserted-by":"crossref","unstructured":"Oxenkrug, G. (2024). Anthranilic Acid\u2013G-Protein coupled receptor109A\u2013Cytosolic Phospholipase A2\u2013Myelin\u2013Cognition Cascade: A New Target for the Treatment\/Prevention of Cognitive Impairment in Schizophrenia, Dementia, and Aging. Int. J. Mol. Sci., 25.","DOI":"10.3390\/ijms252413269"},{"key":"ref_80","doi-asserted-by":"crossref","unstructured":"Berlinguer-Palmini, R., Masi, A., Narducci, R., Cavone, L., Maratea, D., Cozzi, A., Sili, M., Moroni, F., and Mannaioni, G. (2013). GPR35 Activation Reduces Ca2+Transients and Contributes to the Kynurenic Acid-Dependent Reduction of Synaptic Activity at CA3-CA1 Synapses. PLoS ONE, 8.","DOI":"10.1371\/journal.pone.0082180"},{"key":"ref_81","doi-asserted-by":"crossref","first-page":"3095","DOI":"10.4103\/NRR.NRR-D-24-00607","article-title":"Exploring the interaction between the gut microbiota and cyclic adenosine monophosphate-protein kinase A signaling pathway: A potential therapeutic approach for neurodegenerative diseases","volume":"20","author":"Deng","year":"2025","journal-title":"Neural Regen Res."},{"key":"ref_82","doi-asserted-by":"crossref","first-page":"97","DOI":"10.1016\/S0079-6123(07)00006-4","article-title":"Regulation of hippocampus-dependent memory by cyclic AMP-dependent protein kinase","volume":"169","author":"Abel","year":"2008","journal-title":"Prog. Brain Res."}],"container-title":["Biomolecules"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/2218-273X\/16\/4\/603\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2026,4,20]],"date-time":"2026-04-20T10:26:39Z","timestamp":1776680799000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/2218-273X\/16\/4\/603"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2026,4,18]]},"references-count":82,"journal-issue":{"issue":"4","published-online":{"date-parts":[[2026,4]]}},"alternative-id":["biom16040603"],"URL":"https:\/\/doi.org\/10.3390\/biom16040603","relation":{},"ISSN":["2218-273X"],"issn-type":[{"value":"2218-273X","type":"electronic"}],"subject":[],"published":{"date-parts":[[2026,4,18]]}}}