{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,2,10]],"date-time":"2026-02-10T07:57:09Z","timestamp":1770710229051,"version":"3.49.0"},"reference-count":46,"publisher":"MDPI AG","issue":"3","license":[{"start":{"date-parts":[[2026,2,5]],"date-time":"2026-02-05T00:00:00Z","timestamp":1770249600000},"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>Apelin is a postnatal peptide implicated in gastrointestinal maturation, yet its combined effects on mucosa, enteric plexuses, and gut-derived appetite signals are not well defined. We investigated the impact of chronic intragastric apelin-13 on the stomach and small intestine of unweaned rats. Twelve Wistar pups of both sexes received apelin-13 (100 nmol\/kg body weight, twice daily) or saline from postnatal day 10 for 14 days. After euthanasia, gastric and small-intestinal samples were processed for histomorphometry, neurofilament immunohistochemistry of myenteric and submucosal plexuses, and quantitative staining for ghrelin and leptin. Apelin-13 increased gastric mucosal thickness and pit and gland height, enlarged zymogen cells, and reduced muscularis propria thickness, while leaving submucosa and parietal cell area unchanged. In the small intestine, apelin produced a clear proximal-distal gradient, with enhanced villus-mucosa indices proximally and reduced indices in mid-to-distal jejunum, alongside broader crypt remodeling. Enterocyte and goblet cell dimensions changed in parallel with these regional shifts. Myenteric and submucosal ganglia were also remodeled in a segment-dependent manner. Ghrelin immunoreactivity increased in most regions, whereas leptin showed opposite proximal and distal responses. Overall, early-life luminal apelin-13 reshapes gastric and intestinal architecture and local hormone expression.<\/jats:p>","DOI":"10.3390\/ani16030497","type":"journal-article","created":{"date-parts":[[2026,2,5]],"date-time":"2026-02-05T11:13:01Z","timestamp":1770289981000},"page":"497","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["Gastric and Small-Intestinal Morphological Remodeling After Intragastric Apelin-13 Administration in Unweaned Rats"],"prefix":"10.3390","volume":"16","author":[{"ORCID":"https:\/\/orcid.org\/0000-0003-2469-6113","authenticated-orcid":false,"given":"Sylwia","family":"Szyma\u0144czyk","sequence":"first","affiliation":[{"name":"Department of Animal Physiology, Faculty of Veterinary Medicine, University of Life Sciences in Lublin, 20-950 Lublin, Poland"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-5630-4968","authenticated-orcid":false,"given":"Cezary","family":"Osiak-Wicha","sequence":"additional","affiliation":[{"name":"Department of Animal Anatomy and Histology, Faculty of Veterinary Medicine, University of Life Sciences in Lublin, 20-950 Lublin, Poland"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-7790-3780","authenticated-orcid":false,"given":"Katarzyna","family":"Kras","sequence":"additional","affiliation":[{"name":"Department of Animal Anatomy and Histology, Faculty of Veterinary Medicine, University of Life Sciences in Lublin, 20-950 Lublin, Poland"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-0681-7065","authenticated-orcid":false,"given":"Ma\u0142gorzata","family":"Kapica","sequence":"additional","affiliation":[{"name":"Department of Animal Physiology, Faculty of Veterinary Medicine, University of Life Sciences in Lublin, 20-950 Lublin, Poland"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-9145-1960","authenticated-orcid":false,"given":"Iwona","family":"Puzio","sequence":"additional","affiliation":[{"name":"Department of Animal Physiology, Faculty of Veterinary Medicine, University of Life Sciences in Lublin, 20-950 Lublin, Poland"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Hanna","family":"Antushevich","sequence":"additional","affiliation":[{"name":"Department of Genetic Engineering, The Kielanowski Institute of Animal Physiology and Nutrition, Polish Academy of Sciences, 05-110 Jab\u0142onna, Poland"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Atsukazu","family":"Kuwahara","sequence":"additional","affiliation":[{"name":"Laboratory of Physiology, Institute for Environmental Sciences, University of Shizuoka, 52-1 Yada, Suruga-ku, Shizuoka 422-8526, Japan"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Ikuo","family":"Kato","sequence":"additional","affiliation":[{"name":"Department of Psychosomatic Internal Medicine, Kagoshima University Graduate School of Medical and Dental Sciences, Kagoshima 890-8544, Japan"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Iwona","family":"\u0141uszczewska-Sierakowska","sequence":"additional","affiliation":[{"name":"Department of Correct Clinical and Imaging Anatomy, Faculty of Medical Sciences, Medical University of Lublin, 20-090 Lublin, Poland"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-3643-3524","authenticated-orcid":false,"given":"Marcin B.","family":"Arciszewski","sequence":"additional","affiliation":[{"name":"Department of Animal Anatomy and Histology, Faculty of Veterinary Medicine, University of Life Sciences in Lublin, 20-950 Lublin, Poland"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1968","published-online":{"date-parts":[[2026,2,5]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"471","DOI":"10.1006\/bbrc.1998.9489","article-title":"Isolation and Characterization of a Novel Endogenous Peptide Ligand for the Human APJ Receptor","volume":"251","author":"Tatemoto","year":"1998","journal-title":"Biochem. 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