{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2025,10,10]],"date-time":"2025-10-10T00:52:55Z","timestamp":1760057575980,"version":"build-2065373602"},"reference-count":60,"publisher":"MDPI AG","issue":"4","license":[{"start":{"date-parts":[[2025,2,12]],"date-time":"2025-02-12T00:00:00Z","timestamp":1739318400000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Animals"],"abstract":"<jats:p>The state of frailty is a clinical\u2013biological syndrome that affects the older population with a higher risk of functional dependence. Animal models can provide a tool to study this complex scenario. In the present work, we analyzed the physical and behavioral hallmarks of end-point status in 16-month-old mice (C57BL\/6J) according to animal welfare regulations compared to age-matched counterparts with normal aging. A group of 6-month-old mice was added to control for age bias. First, we identified \u2018structural kyphosis\u2019 (visible and unmodifiable deformation in locomotion) correlated with piloerection as the hallmarks of the physical frailty phenotype compared to the \u2018postural kyphosis\u2019 (adjustment to counteract increased visceral volume but attenuated during locomotion) of old mice with normal aging. Alopecia (barbering) was presented in both old groups. Normal levels of exploratory activity in the corner test for neophobia and triceps surae muscle weight but an increased latency of rearing indicated the poorest emotional phenotype, with a possible contribution of structural kyphosis. The presence of hepatomegaly and splenomegaly counteracted the significant WAT loss commonly associated with end-of-life traits, which should have a normal body weight but preserved muscle mass.<\/jats:p>","DOI":"10.3390\/ani15040521","type":"journal-article","created":{"date-parts":[[2025,2,12]],"date-time":"2025-02-12T04:37:04Z","timestamp":1739335024000},"page":"521","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["Phenotypical, Behavioral, and Systemic Hallmarks in End-Point Mouse Scenarios"],"prefix":"10.3390","volume":"15","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-1057-9840","authenticated-orcid":false,"given":"Lidia","family":"Castillo-Mariqueo","sequence":"first","affiliation":[{"name":"Institut de Neuroci\u00e8ncies, Universitat Aut\u00f2noma de Barcelona, Cerdanyola del Vall\u00e8s, 08193 Barcelona, Spain"},{"name":"Department of Psychiatry and Forensic Medicine, School of Medicine, Universitat Aut\u00f2noma de Barcelona, Cerdanyola del Vall\u00e8s, 08193 Barcelona, Spain"},{"name":"Departamento de Procesos Terape\u00faticos, Facultad de Ciencias de la Salud, Universidad Cat\u00f3lica de Temuco, Temuco 4780000, Chile"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Daniel","family":"Alveal-Mellado","sequence":"additional","affiliation":[{"name":"Institut de Neuroci\u00e8ncies, Universitat Aut\u00f2noma de Barcelona, Cerdanyola del Vall\u00e8s, 08193 Barcelona, Spain"},{"name":"Department of Psychiatry and Forensic Medicine, School of Medicine, Universitat Aut\u00f2noma de Barcelona, Cerdanyola del Vall\u00e8s, 08193 Barcelona, Spain"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-4091-489X","authenticated-orcid":false,"given":"Lydia","family":"Gim\u00e9nez-Llort","sequence":"additional","affiliation":[{"name":"Institut de Neuroci\u00e8ncies, Universitat Aut\u00f2noma de Barcelona, Cerdanyola del Vall\u00e8s, 08193 Barcelona, Spain"},{"name":"Department of Psychiatry and Forensic Medicine, School of Medicine, Universitat Aut\u00f2noma de Barcelona, Cerdanyola del Vall\u00e8s, 08193 Barcelona, Spain"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1968","published-online":{"date-parts":[[2025,2,12]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"283","DOI":"10.1146\/annurev-animal-022114-110829","article-title":"Animal models of aging research: Implications for human aging and age-related diseases","volume":"3","author":"Mitchell","year":"2015","journal-title":"Annu. 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