{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,9,26]],"date-time":"2026-09-26T18:09:08Z","timestamp":1790446148443,"version":"4.1.0"},"reference-count":103,"publisher":"MDPI AG","issue":"13","license":[{"start":{"date-parts":[[2021,6,30]],"date-time":"2021-06-30T00:00:00Z","timestamp":1625011200000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/501100001659","name":"Deutsche Forschungsgemeinschaft","doi-asserted-by":"publisher","award":["290878970-GRK 2271"],"award-info":[{"award-number":["290878970-GRK 2271"]}],"id":[{"id":"10.13039\/501100001659","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["IJMS"],"abstract":"<jats:p>Anxiety disorders are associated with a failure to sufficiently extinguish fear memories. The serotonergic system (5-hydroxytryptamine, 5-HT) with the 5-HT transporter (5-HTT, SERT) is strongly implicated in the regulation of anxiety and fear. In the present study, we examined the effects of SERT deficiency on fear extinction in a differential fear conditioning paradigm in male and female rats. Fear-related behavior displayed during acquisition, extinction, and recovery, was measured through quantification of immobility and alarm 22-kHz ultrasonic vocalizations (USV). Trait-like inter-individual differences in novelty-seeking, anxiety-related behavior, habituation learning, cognitive performance, and pain sensitivity were examined for their predictive value in forecasting fear extinction. Our results show that SERT deficiency strongly affected the emission of 22-kHz USV during differential fear conditioning. During acquisition, extinction, and recovery, SERT deficiency consistently led to a reduction in 22-kHz USV emission. While SERT deficiency did not affect immobility during acquisition, genotype differences started to emerge during extinction, and during recovery rats lacking SERT showed higher levels of immobility than wildtype littermate controls. Recovery was reflected in increased levels of immobility but not 22-kHz USV emission. Prominent sex differences were evident. Among several measures for trait-like inter-individual differences, anxiety-related behavior had the best predictive quality.<\/jats:p>","DOI":"10.3390\/ijms22137088","type":"journal-article","created":{"date-parts":[[2021,6,30]],"date-time":"2021-06-30T10:03:19Z","timestamp":1625047399000},"page":"7088","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":13,"title":["Fear Extinction and Predictive Trait-Like Inter-Individual Differences in Rats Lacking the Serotonin Transporter"],"prefix":"10.3390","volume":"22","author":[{"given":"Maria","family":"Willadsen","sequence":"first","affiliation":[{"name":"Behavioral Neuroscience, Experimental and Biological Psychology, Faculty of Psychology, Philipps-University of Marburg, Gutenberg-Str. 18, D-35032 Marburg, Germany"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Metin","family":"Uengoer","sequence":"additional","affiliation":[{"name":"Associative Learning, Experimental and Biological Psychology, Faculty of Psychology, Philipps-University of Marburg, Gutenberg-Str. 18, D-35032 Marburg, Germany"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Anna","family":"S\u0142ugocka","sequence":"additional","affiliation":[{"name":"Department for Experimental Medicine, Faculty of Medical Sciences in Katowice, Medical University of Silesia, Medyk\u00f3w 4, 40-752 Katowice, Poland"},{"name":"Department of Physiology, Faculty of Medical Sciences in Katowice, Medical University of Silesia, Medyk\u00f3w 18, 40-752 Katowice, Poland"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-4686-3974","authenticated-orcid":false,"given":"Rainer K.W.","family":"Schwarting","sequence":"additional","affiliation":[{"name":"Behavioral Neuroscience, Experimental and Biological Psychology, Faculty of Psychology, Philipps-University of Marburg, Gutenberg-Str. 18, D-35032 Marburg, Germany"},{"name":"Center for Mind, Brain and Behavior, Philipps-University of Marburg, Hans-Meerwein-Str. 6, D-35032 Marburg, Germany"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-7621-1010","authenticated-orcid":false,"given":"Judith R.","family":"Homberg","sequence":"additional","affiliation":[{"name":"Department of Cognitive Neuroscience, Donders Institute for Brain, Cognition and Behaviour, Radboud University Nijmegen Medical Centre, Kapittelweg 29, 6525 EN Nijmegen, The Netherlands"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-6986-5684","authenticated-orcid":false,"given":"Markus","family":"W\u00f6hr","sequence":"additional","affiliation":[{"name":"Behavioral Neuroscience, Experimental and Biological Psychology, Faculty of Psychology, Philipps-University of Marburg, Gutenberg-Str. 18, D-35032 Marburg, Germany"},{"name":"Center for Mind, Brain and Behavior, Philipps-University of Marburg, Hans-Meerwein-Str. 6, D-35032 Marburg, Germany"},{"name":"KU Leuven, Faculty of Psychology and Educational Sciences, Research Unit Brain and Cognition, Laboratory of Biological Psychology, Social and Affective Neuroscience Research Group, B-3000 Leuven, Belgium"},{"name":"KU Leuven, Leuven Brain Institute, B-3000 Leuven, Belgium"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2021,6,30]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","unstructured":"APA (2013). 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