Citation: Alexa, A.I.; Zamfir, C.L.; Bogd˘ anici, C.M.; Oancea, A.; Mas , taleru, A.; Abdulan, I.M.; Br˘ anis , teanu, D.C.; Ciobîc ˘ a, A.; Balmus , , M.; Stratulat-Alexa, T.; et al. The Impact of Chronic Stress on Behavior and Body Mass in New Animal Models. Brain Sci. 2023, 13, 1492. https://doi.org/10.3390/ brainsci13101492 Received: 15 September 2023 Revised: 17 October 2023 Accepted: 20 October 2023 Published: 22 October 2023 Copyright: © 2023 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ 4.0/). brain sciences Article The Impact of Chronic Stress on Behavior and Body Mass in New Animal Models Anisia Iuliana Alexa 1 , Carmen Lăcrămioara Zamfir 2 , Camelia Margareta Bogdănici 1 , Andra Oancea 3, * , Alexandra Mas , taleru 3,† , Irina Mihaela Abdulan 3,† , Daniel Constantin Brănis , teanu 1 , Alin Ciobîcă 4,5,6,7 , Miruna Balmus , 8 , Teodora Stratulat-Alexa 9 , Roxana Elena Ciuntu 1 , Florentina Severin 10 ,Mădălina Mocanu 11 and Maria Magdalena Leon 3 1 Department of Surgery II, Discipline of Ophthalmology, “Grigore T. Popa” University of Medicine and Pharmacy, 700115 Iasi, Romania; alexa_anisia@yahoo.com (A.I.A.); camelia.bogdanici@umfiasi.ro (C.M.B.); dbranisteanu@yahoo.com (D.C.B.); roxana-elena.ciuntu@umfiasi.ro (R.E.C.) 2 Department of Morpho-Funct , ional Sciences I, Discipline of Histology, “Grigore T. Popa” University of Medicine and Pharmacy, 700115 Iasi, Romania; carmen.zamfir@umfiasi.ro 3 Department of Medical Specialties I, “Grigore T. Popa” University of Medicine and Pharmacy, 700115 Iasi, Romania; alexandra.mastaleru@gmail.com (A.M.); irina.abdulan@yahoo.com (I.M.A.); leon_mariamagdalena@yahoo.com (M.M.L.) 4 Department of Biology, Faculty of Biology, “Alexandru Ioan Cuza” University Iasi, 700505 Iasi, Romania 5 Center of Biomedical Research, Romanian Academy, 700506 Iasi, Romania 6 Academy of Romanian Scientists, Str Splaiul Independentei no. 54, Sector 5, 050094 Bucharest, Romania 7 Preclinical Department, Apollonia University, Pacurari Street 11, 700511 Iasi, Romania 8 Department of Exact Sciences and Natural Sciences, Institute of Interdisciplinary Research, “Alexandru Ioan Cuza” University of Iasi, Alexandru Lapusneanu Street, No. 26, 700057 Iasi, Romania; balmus.ioanamiruna@yahoo.com 9 Department of Medical Oncology, Discipline of Oncology-Radiation Therapy, “Grigore T. Popa” University of Medicine and Pharmacy, 700115 Iasi, Romania; teodora.alexa-stratulat@umfiasi.ro 10 Department of Surgery II, Discipline of Oto Rhino Laryngology, “Grigore T. Popa” University of Medicine and Pharmacy, 700115 Iasi, Romania; florentina.severin@gmail.com 11 Department of Medical Health III, Discipline of Dermatology, “Grigore T. Popa” University of Medicine and Pharmacy, 700115 Iasi, Romania; drmadalinamocanu@yahoo.com * Correspondence: andra.radulescu@yahoo.com † These authors contributed equally to this work. Abstract: (1) Background: Exposure to different sources of stress can have a significant effect on both psychological and physical processes. (2) Methods: The study took place over a period of 34 days and included a total of 40 animals. Regarding the exposure to chronic stressors, we opted for physiological, non-invasive stressors, e.g., running, swimming, and changes in the intensity of light. An unforeseen stress batch was also created that alternated all these stress factors. The animals were divided into five experimental groups, each consisting of eight individuals. In the context of conducting the open field test for behavioral assessment before and after stress exposure, we aimed to investigate the impact of stress exposure on the affective traits of the animals. We also monitored body mass every two days. (3) Results: The control group exhibited an average increase in weight of approximately 30%. The groups exposed to stress factors showed slower growth rates, the lowest being the running group, recording a rate of 20.55%, and the unpredictable stress group at 24.02%. The anxious behavior intensified in the group with unforeseen stress, in the one with light variations, and in the running group. (4) Conclusions: Our research validates the animal model of intermittent light exposure during the dark phase as a novel method of inducing stress. The modification of some anxiety parameters was observed; they vary according to the type of stress. Body mass was found to increase in all groups, especially in the sedentary groups, likely due to the absence of cognitive, spatial, and social stimuli except for cohabitation. Keywords: stress; open field; running; swimming; light exposure variation Brain Sci. 2023, 13, 1492. https://doi.org/10.3390/brainsci13101492 https://www.mdpi.com/journal/brainsci