TY - JOUR T1 - Bagirsak Mikrobiyomu ve Probiyotiklerin Nörotransmitterler üzerine etkileri TT - The Gut Microbiome and the Effects of Probiotics on Neurotransmitters AU - Özalp, Tahir AU - Ural, Kerem AU - Erdoğan, Hasan AU - Paşa, Serdar AU - Erdoğan, Songül AU - Kizilkanat, Ayşe İdil PY - 2026 DA - June Y2 - 2026 JF - Antakya Veteriner Bilimleri Dergisi JO - Antakya Veteriner Bilimleri Dergisi PB - Hatay Mustafa Kemal Üniversitesi WT - DergiPark SN - 2979-9805 SP - 34 EP - 47 VL - 5 IS - 1 LA - tr AB - Bağırsak–beyin ekseni, bağırsak mikrobiyotası ile merkezi sinir sistemi arasında sinirsel, immünolojik ve metabolik yolaklar üzerinden çift yönlü iletişimi sağlayan karmaşık bir ağdır ve bu eksende vagus siniri, enterik sinir sistemi ve mikrobiyal metabolitler temel rol oynar. Son yıllarda artan kanıtlar, bağırsak mikrobiyotasının yalnızca gastrointestinal fizyolojiyi değil; duygu durum, biliş ve davranış gibi merkezi sinir sistemi işlevlerini de düzenlediğini göstermektedir. Mikrobiyota tarafından üretilen veya metabolize edilen nörotransmitterler (glutamat, GABA, serotonin, dopamin ve norepinefrin), bunların öncülleri (triptofan, tirozin) ve kısa zincirli yağ asitleri, afferent vagal yolaklar, enteroendokrin hücreler ve immün sinyalizasyon aracılığıyla beyin fonksiyonlarını etkileyebilmektedir. Bu derleme, bağırsak mikrobiyotası ile nörotransmisyon arasındaki ilişkiyi ayrıntılı biçimde ele alarak, mikrobiyal kaynaklı metabolitlerin nörotransmitter sentezi, salınımı ve reseptör düzeyindeki etkilerini tartışmaktadır. Ayrıca, bağırsak–beyin eksenindeki bozulmaların depresyon, anksiyete, otizm spektrum bozukluğu, Parkinson ve Alzheimer hastalığı gibi nöropsikiyatrik ve nörodejeneratif hastalıkların patofizyolojisiyle ilişkisi değerlendirilmektedir. Mevcut veriler, mikrobiyota hedefli yaklaşımların nörolojik ve psikiyatrik hastalıkların önlenmesi ve tedavisinde umut vadeden stratejiler sunabileceğini düşündürmektedir. KW - bağırsak-beyin ekseni KW - Mikrobiyota KW - Nörotransmiterler KW - Kısa zincirli yağ asitleri N2 - The gut–brain axis is a complex network that enables bidirectional communication between the gut microbiota and the central nervous system through neural, immunological, and metabolic pathways, in which the vagus nerve, the enteric nervous system, and microbial metabolites play central roles. Growing evidence in recent years indicates that the gut microbiota regulates not only gastrointestinal physiology but also central nervous system functions such as mood, cognition, and behavior. Neurotransmitters produced or metabolized by the microbiota (glutamate, GABA, serotonin, dopamine, and norepinephrine), their precursors (tryptophan, tyrosine), and short-chain fatty acids can influence brain function via afferent vagal pathways, enteroendocrine cells, and immune signaling. This review addresses in detail the relationship between the gut microbiota and neurotransmission, discussing the effects of microbially derived metabolites on neurotransmitter synthesis, release, and receptor-level signaling. In addition, the association between disruptions of the gut–brain axis and the pathophysiology of neuropsychiatric and neurodegenerative disorders such as depression, anxiety, autism spectrum disorder, Parkinson’s disease, and Alzheimer’s disease is evaluated. Current evidence suggests that microbiota-targeted approaches may offer promising strategies for the prevention and treatment of neurological and psychiatric disorders. CR - Agus, A., Planchais, J., & Sokol, H. (2018). Gut microbiota regulation of tryptophan metabolism in health and disease. Cell Host & Microbe, 23(6), 716–724. https://doi.org/10.1016/j.chom.2018.05.003 CR - Araque, A., Parpura, V., Sanzgiri, R. P., & Haydon, P. G. (1999). Tripartite synapses: Glia, the unacknowledged partner. Trends in Neurosciences, 22(5), 208–215. https://doi.org/10.1016/S0166-2236(98)01349-6 CR - Asano, Y., Hiramoto, T., Nishino, R., Aiba, Y., Kimura, T., Yoshihara, K., Koga, Y., & Sudo, N. (2012). Critical role of gut microbiota in the production of biologically active, free catecholamines in the gut lumen of mice. American Journal of Physiology – Gastrointestinal and Liver Physiology, 303(11), G1288–G1295. https://doi.org/10.1152/ajpgi.00341.2012 CR - Baj, A., Moro, E., Bistoletti, M., Orlandi, V., Crema, F., & Giaroni, C. (2019). Glutamatergic signaling along the microbiota–gut–brain axis. International Journal of Molecular Sciences, 20(6), 1482. https://doi.org/10.3390/ijms20061482 CR - Bellono, N. W., Bayrer, J. R., Leitch, D. B., Castro, J., Zhang, C., O’Donnell, T. A., Brierley, S. M., Ingraham, H. A., & Julius, D. (2017). Enterochromaffin cells are gut chemosensors that couple to sensory neural pathways. Cell, 170(1), 185–198.e16. https://doi.org/10.1016/j.cell.2017.05.034 CR - Berthoud, H. R., & Neuhuber, W. L. (2000). Functional and chemical anatomy of the afferent vagal system. Autonomic Neuroscience: Basic & Clinical, 85(1–3), 1–17. https://doi.org/10.1016/S1566-0702(00)00215-0 CR - Bianco, F., Bonora, E., Natarajan, D., Vargiolu, M., Thapar, N., Torresan, F., Giancola, F., Boschetti, E., Volta, U., Bazzoli, F., Mazzoni, M., Seri, M., Clavenzani, P., Stanghellini, V., Sternini, C., & De Giorgio, R. (2016). Prucalopride exerts neuroprotection in human enteric neurons. American Journal of Physiology – Gastrointestinal and Liver Physiology, 310(10), G768–G775. https://doi.org/10.1152/ajpgi.00036.2016 CR - Bo, T.-B., Zhang, X.-Y., Kohl, K. D., Wen, J., Tian, S.-J., & Wang, D.-H. (2020). Coprophagy prevention alters microbiome, metabolism, neurochemistry, and cognitive behavior in a small mammal. The ISME Journal, 14(10), 2625–2645. https://doi.org/10.1038/s41396-020-0711-6 CR - Bonaz, B., Bazin, T., & Pellissier, S. (2018). The vagus nerve at the interface of the microbiota–gut–brain axis. Frontiers in Neuroscience, 12, 49. https://doi.org/10.3389/fnins.2018.00049 CR - Borodovitsyna, O., Flamini, M., & Chandler, D. (2017). Noradrenergic modulation of cognition in health and disease. Neural Plasticity, 2017, 6031478. https://doi.org/10.1155/2017/6031478 CR - Bravo, J. A., Forsythe, P., Chew, M. V., Escaravage, E., Savignac, H. M., Dinan, T. G., Bienenstock, J., & Cryan, J. F. (2011). Ingestion of Lactobacillus strain regulates emotional behavior and central GABA receptor expression in a mouse via the vagus nerve. Proceedings of the National Academy of Sciences of the United States of America, 108(38), 16050–16055. https://doi.org/10.1073/pnas.1102999108 CR - Carabotti, M., Scirocco, A., Maselli, M. A., & Severi, C. (2015). The gut–brain axis: Interactions between enteric microbiota, central and enteric nervous systems. Annals of Gastroenterology, 28(2), 203–209. CR - Caspani, G., & Swann, J. (2019). Small talk: Microbial metabolites involved in the signaling from microbiota to brain. Current Opinion in Pharmacology, 48, 99–106. https://doi.org/10.1016/j.coph.2019.08.001 CR - Cervantes-Barragan, L., Chai, J. N., Tianero, M. D., Di Luccia, B., Ahern, P. P., Merriman, J., Cortez, V. S., Caparon, M. G., Donia, M. S., Gilfillan, S., Cella, M., Gordon, J. I., Hsieh, C.-S., & Colonna, M. (2017). Lactobacillus reuteri induces gut intraepithelial CD4+CD8αα+ T cells. Science, 357(6353), 806–810. https://doi.org/10.1126/science.aah5825 CR - Chalazonitis, A., & Rao, M. (2018). Enteric nervous system manifestations of neurodegenerative disease. Brain Research, 1693(Pt B), 207–213. https://doi.org/10.1016/j.brainres.2018.01.011 CR - Chang, C.-H., Lin, C.-H., & Lane, H.-Y. (2020). D-glutamate and gut microbiota in Alzheimer’s disease. International Journal of Molecular Sciences, 21(8), 2676. https://doi.org/10.3390/ijms21082676 CR - Chen, D., Yang, X., Yang, J., Lai, G., Yong, T., Tang, X., Shuai, O., Zhou, G., Xie, Y., & Wu, Q. (2017). Prebiotic effect of fructooligosaccharides from Morinda officinalis on Alzheimer’s disease in rodent models by targeting the microbiota–gut–brain axis. Frontiers in Aging Neuroscience, 9, 403. https://doi.org/10.3389/fnagi.2017.00403 CR - Chen, G., Trombley, P. Q., & van den Pol, A. N. (1995). GABA receptors precede glutamate receptors in hypothalamic development: Differential regulation by astrocytes. Journal of Neurophysiology, 74(4), 1473–1484. https://doi.org/10.1152/jn.1995.74.4.1473 CR - Collison, L. W., Workman, C. J., Kuo, T. T., Boyd, K., Wang, Y., Vignali, K. M., Cross, R., Sehy, D., Blumberg, R. S., & Vignali, D. A. A. (2007). The inhibitory cytokine IL-35 contributes to regulatory T-cell function. Nature, 450(7169), 566–569. https://doi.org/10.1038/nature06306 CR - Cryan, J. F., O’Riordan, K. J., Sandhu, K., Peterson, V., & Dinan, T. G. (2020). The gut microbiome in neurological disorders. The Lancet Neurology, 19(2), 179–194. https://doi.org/10.1016/S1474-4422(19)30356-4 CR - Cui, Y., Miao, K., Niyaphorn, S., & Qu, X. (2020). Production of gamma-aminobutyric acid from lactic acid bacteria: A systematic review. International Journal of Molecular Sciences, 21(3), 995. https://doi.org/10.3390/ijms21030995 CR - Cushing, K., Alvarado, D. M., & Ciorba, M. A. (2015). Butyrate and mucosal inflammation: New scientific evidence supports clinical observation. Clinical and Translational Gastroenterology, 6(8), e108. https://doi.org/10.1038/ctg.2015.34 CR - De Vadder, F., Grasset, E., Mannerås Holm, L., Karsenty, G., Macpherson, A. J., Olofsson, L. E., & Bäckhed, F. (2018). Gut microbiota regulates maturation of the adult enteric nervous system via enteric serotonin networks. Proceedings of the National Academy of Sciences of the United States of America, 115(25), 6458–6463. https://doi.org/10.1073/pnas.1720017115 CR - De Vadder, F., Kovatcheva-Datchary, P., Goncalves, D., Vinera, J., Zitoun, C., Duchampt, A., Bäckhed, F., & Mithieux, G. (2014). Microbiota-generated metabolites promote metabolic benefits via gut–brain neural circuits. Cell, 156(1–2), 84–96. https://doi.org/10.1016/j.cell.2013.12.016 CR - DeCastro, M., Nankova, B. B., Shah, P., Patel, P., Mally, P. V., Mishra, R., & La Gamma, E. F. (2005). Short-chain fatty acids regulate tyrosine hydroxylase gene expression through a cAMP-dependent signaling pathway. Brain Research: Molecular Brain Research, 142(1), 28–38. https://doi.org/10.1016/j.molbrainres.2005.09.002 CR - Dicks, L. M. T., Hurn, D., & Hermanus, D. (2021). Gut bacteria and neuropsychiatric disorders. Microorganisms, 9(12), 2583. https://doi.org/10.3390/microorganisms9122583 CR - Dover, S., & Halpern, Y. S. (1972). Utilization of γ-aminobutyric acid as the sole carbon and nitrogen source by Escherichia coli K-12 mutants. Journal of Bacteriology, 109(2), 835–843. https://doi.org/10.1128/jb.109.2.835-843.1972 CR - Eisenhofer, G., Aneman, A., Friberg, P., Hooper, D., Fändriks, L., Lönroth, H., Hunyady, B., & Mezey, E. (1997). Substantial production of dopamine in the human gastrointestinal tract. The Journal of Clinical Endocrinology & Metabolism, 82(11), 3864–3871. https://doi.org/10.1210/jcem.82.11.4339 CR - El-Salhy, M., Danielsson, A., Stenling, R., & Grimelius, L. (1997). Colonic endocrine cells in inflammatory bowel disease. Journal of Internal Medicine, 242(5), 413–419. https://doi.org/10.1046/j.1365-2796.1997.00237.x CR - Erny, D., Hrabě de Angelis, A. L., Jaitin, D., Wieghofer, P., Staszewski, O., David, E., … Prinz, M. (2015). Host microbiota constantly control maturation and function of microglia in the CNS. Nature Neuroscience, 18(7), 965–977. https://doi.org/10.1038/nn.4030 CR - Frank, D. N., St Amand, A. L., Feldman, R. A., Boedeker, E. C., Harpaz, N., & Pace, N. R. (2007). Molecular-phylogenetic characterization of microbial community imbalances in human inflammatory bowel diseases. Proceedings of the National Academy of Sciences of the United States of America, 104(34), 13780–13785. https://doi.org/10.1073/pnas.0706625104 CR - Frost, G., Sleeth, M. L., Sahuri-Arisoylu, M., Lizarbe, B., Cerdan, S., Brody, L., … Bell, J. D. (2014). The short-chain fatty acid acetate reduces appetite via a central homeostatic mechanism. Nature Communications, 5, 3611. https://doi.org/10.1038/ncomms4611 CR - Galland, L. (2014). The gut microbiome and the brain. Journal of Medicinal Food, 17(12), 1261–1272. https://doi.org/10.1089/jmf.2014.7000 CR - Gao, K., Mu, C.-L., Farzi, A., & Zhu, W.-Y. (2020). Tryptophan metabolism: A link between the gut microbiota and brain. Advances in Nutrition, 11(3), 709–723. https://doi.org/10.1093/advances/nmz127 CR - Gao, K., Pi, Y., Mu, C.-L., Farzi, A., Liu, Z., & Zhu, W.-Y. (2019). Increasing carbohydrate availability in the hindgut promotes hypothalamic neurotransmitter synthesis: Aromatic amino acids linking the microbiota–brain axis. Journal of Neurochemistry, 149(5), 641–659. https://doi.org/10.1111/jnc.14709 CR - Ge, X., Pan, J., Liu, Y., Wang, H., Zhou, W., & Wang, X. (2018). Intestinal crosstalk between microbiota and serotonin and its impact on gut motility. Current Pharmaceutical Biotechnology, 19(3), 190–195. https://doi.org/10.2174/1389201019666180528094202 CR - Generoso, J. S., Giridharan, V. V., Lee, J., Macedo, D., & Barichello, T. (2021). The role of the microbiota–gut–brain axis in neuropsychiatric disorders. Revista Brasileira de Psiquiatria, 43(3), 293–305. https://doi.org/10.1590/1516-4446-2020-0987 CR - Goldstein, A. M., Hofstra, R. M. W., & Burns, A. J. (2013). Building a brain in the gut: Development of the enteric nervous system. Clinical Genetics, 83(4), 307–316. https://doi.org/10.1111/cge.12054 CR - Gomaa, E. Z. (2020). Human gut microbiota/microbiome in health and diseases: A review. Antonie van Leeuwenhoek, 113(12), 2019–2040. https://doi.org/10.1007/s10482-020-01474-7 CR - Gu, F., Wu, Y., Liu, Y., Dou, M., Jiang, Y., & Liang, H. (2020). Lactobacillus casei improves depression-like behavior in rats by the BDNF–TrkB signaling pathway and intestinal microbiota. Food & Function, 11(7), 6148–6157. https://doi.org/10.1039/d0fo00373e CR - Gwak, M.-G., & Chang, S.-Y. (2021). Gut–brain connection: Microbiome, gut barrier, and environmental sensors. Immune Network, 21(3), e20. https://doi.org/10.4110/in.2021.21.e20 CR - Hackett, J. T., & Ueda, T. (2015). Glutamate release. Neurochemical Research, 40(12), 2443–2460. https://doi.org/10.1007/s11064-015-1622-1 CR - Hamamah, S., Aghazarian, A., Nazaryan, A., Hajnal, A., & Covasa, M. (2022). Role of microbiota–gut–brain axis in regulating dopaminergic signaling. Biomedicines, 10(2), 436. https://doi.org/10.3390/biomedicines10020436 CR - Hazan, S. (2020). Rapid improvement in Alzheimer’s disease symptoms following fecal microbiota transplantation: A case report. Journal of International Medical Research, 48(6), 300060520925930. https://doi.org/10.1177/0300060520925930 CR - Heiman, M. L., & Greenway, F. L. (2016). A healthy gastrointestinal microbiome is dependent on dietary diversity. Molecular Metabolism, 5(5), 317–320. https://doi.org/10.1016/j.molmet.2016.02.005 CR - Helton, S. G., & Lohoff, F. W. (2015). Serotonin pathway polymorphisms and the treatment of major depressive disorder and anxiety disorders. Pharmacogenomics, 16(5), 541–553. https://doi.org/10.2217/pgs.15.15 CR - Hoang, T. K., He, B., Wang, T., Tran, D. Q., Rhoads, J. M., & Liu, Y. (2018). Protective effect of Lactobacillus reuteri DSM 17938 against experimental necrotizing enterocolitis is mediated by Toll-like receptor 2. American Journal of Physiology – Gastrointestinal and Liver Physiology, 315(2), G231–G240. https://doi.org/10.1152/ajpgi.00084.2017 CR - Houlden, A., Goldrick, M., Brough, D., Vizi, E. S., Lénárt, N., Martinecz, B., Roberts, I. S., & Denes, A. (2016). Brain injury induces specific changes in the caecal microbiota of mice via altered autonomic activity and mucoprotein production. Brain, Behavior, and Immunity, 57, 10–20. https://doi.org/10.1016/j.bbi.2016.04.003 CR - Hoyles, L., Fernández-Real, J.-M., Federici, M., Serino, M., Abbott, J., Charpentier, J., Heymes, C., Luque, J. L., Anthony, E., Barton, R. H., Chilloux, J., Myridakis, A., Martinez-Gili, L., Moreno-Navarrete, J. M., Benhamed, F., Azalbert, V., Blasco-Baque, V., Puig, J., Xifra, G., … Dumas, M.-E. (2018). Molecular phenomics and metagenomics of hepatic steatosis in non-diabetic obese women. Nature Medicine, 24(7), 1070–1080. https://doi.org/10.1038/s41591-018-0061-3 CR - Hughes, D. T., & Sperandio, V. (2008). Inter-kingdom signalling: Communication between bacteria and their hosts. Nature Reviews Microbiology, 6(2), 111–120. https://doi.org/10.1038/nrmicro1836 CR - Joseph, J., Depp, C., Shih, P.-A. B., Cadenhead, K. S., & Schmid-Schönbein, G. (2017). Modified Mediterranean diet for enrichment of short-chain fatty acids: Potential adjunctive therapeutic to target immune and metabolic dysfunction in schizophrenia? Frontiers in Neuroscience, 11, 155. https://doi.org/10.3389/fnins.2017.00155 CR - Kaelberer, M. M., Buchanan, K. L., Klein, M. E., Barth, B. B., Montoya, M. M., Shen, X., & Bohórquez, D. V. (2018). A gut–brain neural circuit for nutrient sensory transduction. Science, 361(6408), eaat5236. https://doi.org/10.1126/science.aat5236 CR - Kaelberer, M. M., Rupprecht, L. E., Liu, W. W., Weng, P., & Bohórquez, D. V. (2020). Neuropod cells: The emerging biology of gut–brain sensory transduction. Annual Review of Neuroscience, 43, 337–353. https://doi.org/10.1146/annurev-neuro-091619-022657 CR - Kang, D.-W., Adams, J. B., Coleman, D. M., Pollard, E. L., Maldonado, J., McDonough-Means, S., Caporaso, J. G., & Krajmalnik-Brown, R. (2019). Long-term benefit of microbiota transfer therapy on autism symptoms and gut microbiota. Scientific Reports, 9(1), 5821. https://doi.org/10.1038/s41598-019-42183-0 CR - Kang, D.-W., Adams, J. B., Gregory, A. C., Borody, T., Chittick, L., Fasano, A., Khoruts, A., Geis, E., Maldonado, J., McDonough-Means, S., Pollard, E. L., Roux, S., Sadowsky, M. J., Lipson, K. S., Sullivan, M. B., Caporaso, J. G., & Krajmalnik-Brown, R. (2017). Microbiota transfer therapy alters gut ecosystem and improves gastrointestinal and autism symptoms: An open-label study. Microbiome, 5(1), 10. https://doi.org/10.1186/s40168-016-0225-7 CR - Kelly, J. R., Borre, Y., O’Brien, C., Patterson, E., El Aidy, S., Deane, J., Kennedy, P. J., Beers, S., Scott, K., Moloney, G., Hoban, A. E., Scott, L., Fitzgerald, P., Ross, P., Stanton, C., Clarke, G., Cryan, J. F., & Dinan, T. G. (2016b). Transferring the blues: Depression-associated gut microbiota induces neurobehavioural changes in the rat. Journal of Psychiatric Research, 82, 109–118. https://doi.org/10.1016/j.jpsychires.2016.07.019 CR - Kelly, J. R., Clarke, G., Cryan, J. F., & Dinan, T. G. (2016a). Brain–gut–microbiota axis: Challenges for translation in psychiatry. Annals of Epidemiology, 26(5), 366–372. https://doi.org/10.1016/j.annepidem.2016.02.008 CR - Keshavarzian, A., Green, S. J., Engen, P. A., Voigt, R. M., Naqib, A., Forsyth, C. B., Mutlu, E., & Shannon, K. M. (2015). Colonic bacterial composition in Parkinson’s disease. Movement Disorders, 30(10), 1351–1360. https://doi.org/10.1002/mds.26307 CR - Kim, M.-S., Kim, Y., Choi, H., Kim, W., Park, S., Lee, D., Kim, D. K., Kim, H. J., Choi, H., Hyun, D.-W., Lee, J.-Y., Choi, E. Y., Lee, D.-S., Bae, J.-W., & Mook-Jung, I. (2020). Transfer of a healthy microbiota reduces amyloid and tau pathology in an Alzheimer’s disease animal model. Gut, 69(2), 283–294. https://doi.org/10.1136/gutjnl-2018-317431 CR - Kimura, I., Ozawa, K., Inoue, D., Imamura, T., Kimura, K., Maeda, T., Terasawa, K., Kashihara, D., Hirano, K., Tani, T., Takahashi, T., Miyauchi, S., Shioi, G., Inoue, H., & Tsujimoto, G. (2013). The gut microbiota suppresses insulin-mediated fat accumulation via the short-chain fatty acid receptor GPR43. Nature Communications, 4, 1829. https://doi.org/10.1038/ncomms2852 CR - Ko, J. H., & Strafella, A. P. (2012). Dopaminergic neurotransmission in the human brain: New lessons from perturbation and imaging. The Neuroscientist, 18(2), 149–168. https://doi.org/10.1177/1073858411401413 CR - Koch, T. R., Roddy, D. R., & Go, V. L. (1987). Abnormalities of fasting serum concentrations of peptide YY in the idiopathic inflammatory bowel diseases. The American Journal of Gastroenterology, 82(4), 321–326. CR - Kuai, X.-Y., Yao, X.-H., Xu, L.-J., Zhou, Y.-Q., Zhang, L.-P., Liu, Y., Pei, S.-F., & Zhou, C.-L. (2021). Evaluation of fecal microbiota transplantation in Parkinson’s disease patients with constipation. Microbial Cell Factories, 20(1), 98. https://doi.org/10.1186/s12934-021-01589-0 CR - Leeuwendaal, N. K., Stanton, C., O’Toole, P. W., & Beresford, T. P. (2022). Fermented foods, health and the gut microbiome. Nutrients, 14(7), 1527. https://doi.org/10.3390/nu14071527 CR - Li, D., Yu, S., Long, Y., Shi, A., Deng, J., Ma, Y., Wen, J., Li, X., Liu, S., Zhang, Y., Wan, J., Li, N., & Ao, R. (2022). Tryptophan metabolism: Mechanism-oriented therapy for neurological and psychiatric disorders. Frontiers in Immunology, 13, 985378. https://doi.org/10.3389/fimmu.2022.985378 CR - Li, Y., Luo, Z.-Y., Hu, Y.-Y., Bi, Y.-W., Yang, J.-M., Zou, W.-J., Song, Y.-L., Li, S., Shen, T., Li, S.-J., Huang, L., Zhou, A.-J., Gao, T.-M., & Li, J.-M. (2020). The gut microbiota regulates autism-like behavior by mediating vitamin B6 homeostasis in EphB6-deficient mice. Microbiome, 8(1), 120. https://doi.org/10.1186/s40168-020-00884-z CR - Liu, G., Chong, H.-X., Chung, F. Y.-L., Li, Y., & Liong, M.-T. (2020). Lactobacillus plantarum DR7 modulated bowel movement and gut microbiota associated with dopamine and serotonin pathways in stressed adults. International Journal of Molecular Sciences, 21(13), 4608. https://doi.org/10.3390/ijms21134608 CR - Liu, J., Fu, Y., Zhang, H., Wang, J., Zhu, J., Wang, Y., Guo, Y., Wang, G., Xu, T., Chu, M., & Wang, F. (2017). The hepatoprotective effect of the probiotic Clostridium butyricum against carbon tetrachloride-induced acute liver damage in mice. Food & Function, 8(11), 4042–4052. https://doi.org/10.1039/c7fo00355b CR - Lukić, I., Ivković, S., Mitić, M., & Adžić, M. (2022). Tryptophan metabolites in depression: Modulation by gut microbiota. Frontiers in Behavioral Neuroscience, 16, 987697. https://doi.org/10.3389/fnbeh.2022.987697 CR - Luqman, A., Nega, M., Nguyen, M.-T., Ebner, P., & Götz, F. (2018). SadA-expressing staphylococci in the human gut show increased cell adherence and internalization. Cell Reports, 22(2), 535–545. https://doi.org/10.1016/j.celrep.2017.12.058 CR - MahmoudianDehkordi, S., Arnold, M., Nho, K., Ahmad, S., Jia, W., Xie, G., Louie, G., Kueider-Paisley, A., Moseley, M. A., Thompson, J. W., St John Williams, L., Tenenbaum, J. D., Blach, C., Baillie, R., Han, X., Bhattacharyya, S., Toledo, J. B., Schafferer, S., Klein, S., … Alzheimer’s Disease Neuroimaging Initiative & the Alzheimer Disease Metabolomics Consortium. (2019). Altered bile acid profile associates with cognitive impairment in Alzheimer’s disease: An emerging role for gut microbiome. Alzheimer’s & Dementia, 15(1), 76–92. https://doi.org/10.1016/j.jalz.2018.07.217 CR - Maini Rekdal, V., Bess, E. N., Bisanz, J. E., Turnbaugh, P. J., & Balskus, E. P. (2019). Discovery and inhibition of an interspecies gut bacterial pathway for levodopa metabolism. Science, 364(6445), eaau6323. https://doi.org/10.1126/science.aau6323 CR - Masato, A., Plotegher, N., Boassa, D., & Bubacco, L. (2019). Impaired dopamine metabolism in Parkinson’s disease pathogenesis. Molecular Neurodegeneration, 14(1), 35. https://doi.org/10.1186/s13024-019-0332-6 CR - Montanari, M., Martella, G., Bonsi, P., & Meringolo, M. (2022). Autism spectrum disorder: Focus on glutamatergic neurotransmission. International Journal of Molecular Sciences, 23(7), 3861. https://doi.org/10.3390/ijms23073861 CR - Nakayama, Y., Hashimoto, K.-I., Sawada, Y., Sokabe, M., Kawasaki, H., & Martinac, B. (2018). Corynebacterium glutamicum mechanosensitive channels: Towards unpuzzling “glutamate efflux” for amino acid production. Biophysical Reviews, 10(5), 1359–1369. https://doi.org/10.1007/s12551-018-0452-1 CR - Nankova, B. B., Agarwal, R., MacFabe, D. F., & La Gamma, E. F. (2014). Enteric bacterial metabolites propionic and butyric acid modulate gene expression, including CREB-dependent catecholaminergic neurotransmission, in PC12 cells: Possible relevance to autism spectrum disorders. PLOS ONE, 9(8), e103740. https://doi.org/10.1371/journal.pone.0103740 CR - Nicholson, J. K., Holmes, E., Kinross, J., Burcelin, R., Gibson, G., Jia, W., & Pettersson, S. (2012). Host–gut microbiota metabolic interactions. Science, 336(6086), 1262–1267. https://doi.org/10.1126/science.1223813 CR - O’Donnell, J., Zeppenfeld, D., McConnell, E., Pena, S., & Nedergaard, M. (2012). Norepinephrine: A neuromodulator that boosts the function of multiple cell types to optimize CNS performance. Neurochemical Research, 37(11), 2496–2512. https://doi.org/10.1007/s11064-012-0818-x CR - O’Donnell, P. M., Aviles, H., Lyte, M., & Sonnenfeld, G. (2006). Enhancement of in vitro growth of pathogenic bacteria by norepinephrine: Importance of inoculum density and role of transferrin. Applied and Environmental Microbiology, 72(7), 5097–5099. https://doi.org/10.1128/AEM.00075-06 CR - Onaolapo, A. Y., & Onaolapo, O. J. (2021). Glutamate and depression: Reflecting a deepening knowledge of the gut and brain effects of a ubiquitous molecule. World Journal of Psychiatry, 11(7), 297–315. https://doi.org/10.5498/wjp.v11.i7.297 CR - Qiu, W., Wu, M., Liu, S., Chen, B., Pan, C., Yang, M., & Wang, K.-J. (2017). Suppressive immunoregulatory effects of three antidepressants via inhibition of the nuclear factor-κB activation assessed using primary macrophages of carp (Cyprinus carpio). Toxicology and Applied Pharmacology, 322, 1–8. https://doi.org/10.1016/j.taap.2017.03.002 CR - Rathour, D., Shah, S., Khan, S., Singh, P. K., Srivastava, S., Singh, S. B., & Khatri, D. K. (2023). Role of gut microbiota in depression: Understanding molecular pathways, recent research, and future direction. Behavioural Brain Research, 436, 114081. https://doi.org/10.1016/j.bbr.2022.114081 CR - Roth, W., Zadeh, K., Vekariya, R., Ge, Y., & Mohamadzadeh, M. (2021). Tryptophan metabolism and gut–brain homeostasis. International Journal of Molecular Sciences, 22(6), 2973. https://doi.org/10.3390/ijms22062973 CR - Sarasa, S. B., Mahendran, R., Muthusamy, G., Thankappan, B., Selta, D. R. F., & Angayarkanni, J. (2020). A brief review on the non-protein amino acid, gamma-aminobutyric acid (GABA): Its production and role in microbes. Current Microbiology, 77(4), 534–544. https://doi.org/10.1007/s00284-019-01839-w CR - Satyanarayana, M. (2025, January 21). Serotonin helps gut microbes thrive. Chemical & Engineering News. https://cen.acs.org/biological-chemistry/microbiome/Serotonin-helps-gut-microbes-thrive/97/i35 CR - Schroeder, F. A., Lin, C. L., Crusio, W. E., & Akbarian, S. (2007). Antidepressant-like effects of the histone deacetylase inhibitor, sodium butyrate, in the mouse. Biological Psychiatry, 62(1), 55–64. https://doi.org/10.1016/j.biopsych.2006.06.036 CR - Shen, T., Yue, Y., He, T., Huang, C., Qu, B., Lv, W., & Lai, H.-Y. (2021). The association between the gut microbiota and Parkinson’s disease: A meta-analysis. Frontiers in Aging Neuroscience, 13, 636545. https://doi.org/10.3389/fnagi.2021.636545 CR - Singh, V., Roth, S., Llovera, G., Sadler, R., Garzetti, D., Stecher, B., Dichgans, M., & Liesz, A. (2016). Microbiota dysbiosis controls the neuroinflammatory response after stroke. The Journal of Neuroscience, 36(28), 7428–7440. https://doi.org/10.1523/JNEUROSCI.1114-16.2016 CR - Sitkin, S., Vakhitov, T., & Pokrotnieks, J. (2021). Oral butyrate modulates the gut microbiota in patients with inflammatory bowel disease, most likely by reversing proinflammatory metabolic reprogramming of colonocytes. Neurogastroenterology & Motility, 33(1), e14038. https://doi.org/10.1111/nmo.14038 CR - Specian, R. D., & Neutra, M. R. (1980). Mechanism of rapid mucus secretion in goblet cells stimulated by acetylcholine. The Journal of Cell Biology, 85(3), 626–640. https://doi.org/10.1083/jcb.85.3.626 CR - Stefano, G. B., Pilonis, N., Ptacek, R., Raboch, J., Vnukova, M., & Kream, R. M. (2018). Gut, microbiome, and brain regulatory axis: Relevance to neurodegenerative and psychiatric disorders. Cellular and Molecular Neurobiology, 38(6), 1197–1206. https://doi.org/10.1007/s10571-018-0589-2 CR - Stopińska, K., Radziwoń-Zaleska, M., & Domitrz, I. (2021). The microbiota–gut–brain axis as a key to neuropsychiatric disorders: A mini review. Journal of Clinical Medicine, 10(20), 4640. https://doi.org/10.3390/jcm10204640 CR - Strandwitz, P. (2018). Neurotransmitter modulation by the gut microbiota. Brain Research, 1693(Pt B), 128–133. https://doi.org/10.1016/j.brainres.2018.03.015 CR - Strandwitz, P., Kim, K. H., Terekhova, D., Liu, J. K., Sharma, A., Levering, J., McDonald, D., Dietrich, D., Ramadhar, T. R., Lekbua, A., Mroue, N., Liston, C., Stewart, E. J., Dubin, M. J., Zengler, K., Knight, R., Gilbert, J. A., Clardy, J., & Lewis, K. (2019). GABA-modulating bacteria of the human gut microbiota. Nature Microbiology, 4(3), 396–403. https://doi.org/10.1038/s41564-018-0307-3 CR - Sun, L.-J., Li, J.-N., & Nie, Y.-Z. (2020). Gut hormones in microbiota–gut–brain cross-talk. Chinese Medical Journal, 133(7), 826–833. https://doi.org/10.1097/CM9.0000000000000706 CR - Sun, M.-F., & Shen, Y.-Q. (2018). Dysbiosis of gut microbiota and microbial metabolites in Parkinson’s disease. Ageing Research Reviews, 45, 53–61. https://doi.org/10.1016/j.arr.2018.04.004 CR - Sun, M.-F., Zhu, Y.-L., Zhou, Z.-L., Jia, X.-B., Xu, Y.-D., Yang, Q., Cui, C., & Shen, Y.-Q. (2018). Neuroprotective effects of fecal microbiota transplantation on MPTP-induced Parkinson’s disease mice: Gut microbiota, glial reaction and TLR4/TNF-α signaling pathway. Brain, Behavior, and Immunity, 70, 48–60. https://doi.org/10.1016/j.bbi.2018.02.005 CR - Tsai, M.-F., & Miller, C. (2013). Substrate selectivity in arginine-dependent acid resistance in enteric bacteria. Proceedings of the National Academy of Sciences of the United States of America, 110(15), 5893–5897. https://doi.org/10.1073/pnas.1301442110 CR - Tsavkelova, E. A., Botvinko, I. V., Kudrin, V. S., & Oleskin, A. V. (2000). Detection of neurotransmitter amines in microorganisms with the use of high-performance liquid chromatography. Doklady Biochemistry, 372(1–6), 115–117. CR - Unger, M. M., Spiegel, J., Dillmann, K.-U., Grundmann, D., Philippeit, H., Bürmann, J., Faßbender, K., Schwiertz, A., & Schäfer, K.-H. (2016). Short chain fatty acids and gut microbiota differ between patients with Parkinson’s disease and age-matched controls. Parkinsonism & Related Disorders, 32, 66–72. https://doi.org/10.1016/j.parkreldis.2016.08.019 CR - van de Wouw, M., Boehme, M., Lyte, J. M., Wiley, N., Strain, C., O’Sullivan, O., Clarke, G., Stanton, C., Dinan, T. G., & Cryan, J. F. (2018). Short-chain fatty acids: Microbial metabolites that alleviate stress-induced brain–gut axis alterations. The Journal of Physiology, 596(20), 4923–4944. https://doi.org/10.1113/JP276431 CR - Wang, H.-B., Wang, P.-Y., Wang, X., Wan, Y.-L., & Liu, Y.-C. (2012). Butyrate enhances intestinal epithelial barrier function via up-regulation of tight junction protein Claudin-1 transcription. Digestive Diseases and Sciences, 57(12), 3126–3135. https://doi.org/10.1007/s10620-012-2259-4 CR - Wang, Y., Tong, Q., Ma, S.-R., Zhao, Z.-X., Pan, L.-B., Cong, L., Han, P., Peng, R., Yu, H., Lin, Y., Gao, T.-L., Shou, J.-W., Li, X.-Y., Zhang, X.-F., Zhang, Z.-W., Fu, J., Wen, B.-Y., Yu, J.-B., Cao, X., & Jiang, J.-D. (2021). Oral berberine improves brain dopa/dopamine levels to ameliorate Parkinson’s disease by regulating gut microbiota. Signal Transduction and Targeted Therapy, 6(1), 77. https://doi.org/10.1038/s41392-020-00456-5 CR - Wu, L., Han, Y., Zheng, Z., Peng, G., Liu, P., Yue, S., Zhu, S., Chen, J., Lv, H., Shao, L., Sheng, Y., Wang, Y., Li, L., Li, L., & Wang, B. (2021). Altered gut microbial metabolites in amnestic mild cognitive impairment and Alzheimer’s disease: Signals in host–microbe interplay. Nutrients, 13(1), 228. https://doi.org/10.3390/nu13010228 CR - Yang, X., Lou, J., Shan, W., Ding, J., Jin, Z., Hu, Y., Du, Q., Liao, Q., Xie, R., & Xu, J. (2021). Pathophysiologic role of neurotransmitters in digestive diseases. Frontiers in Physiology, 12, 567650. https://doi.org/10.3389/fphys.2021.567650 CR - Yano, J. M., Yu, K., Donaldson, G. P., Shastri, G. G., Ann, P., Ma, L., Nagler, C. R., Ismagilov, R. F., Mazmanian, S. K., & Hsiao, E. Y. (2015). Indigenous bacteria from the gut microbiota regulate host serotonin biosynthesis. Cell, 161(2), 264–276. https://doi.org/10.1016/j.cell.2015.02.047 CR - Yelamanchi, S. D., Jayaram, S., Thomas, J. K., Gundimeda, S., Khan, A. A., Singhal, A., Keshava Prasad, T. S., Pandey, A., Somani, B. L., & Gowda, H. (2016). A pathway map of glutamate metabolism. Journal of Cell Communication and Signaling, 10(1), 69–75. https://doi.org/10.1007/s12079-015-0315-5 CR - Yong, S. J., Tong, T., Chew, J., & Lim, W. L. (2020). Antidepressive mechanisms of probiotics and their therapeutic potential. Frontiers in Neuroscience, 13, 1361. https://doi.org/10.3389/fnins.2019.01361. CR - Yoon, B.-E., & Lee, C. J. (2014). GABA as a rising gliotransmitter. Frontiers in Neural Circuits, 8, 141. https://doi.org/10.3389/fncir.2014.00141 CR - Zhou, Y., & Danbolt, N. C. (2014). Glutamate as a neurotransmitter in the healthy brain. Journal of Neural Transmission, 121(8), 799–817. https://doi.org/10.1007/s00702-014-1180-8 CR - Zhuang, Z.-Q., Shen, L.-L., Li, W.-W., Fu, X., Zeng, F., Gui, L., Lü, Y., Cai, M., Zhu, C., Tan, Y.-L., Zheng, P., Li, H.-Y., Zhu, J., Zhou, H.-D., Bu, X.-L., & Wang, Y.-J. (2018). Gut microbiota is altered in patients with Alzheimer’s disease. Journal of Alzheimer’s Disease, 63(4), 1337–1346. https://doi.org/10.3233/JAD-180176 UR - https://dergipark.org.tr/tr/pub/antakyavet/article/1862607 L1 - https://dergipark.org.tr/tr/download/article-file/5599295 ER -