{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,8,27]],"date-time":"2026-08-27T09:23:50Z","timestamp":1787822630459,"version":"build-2784847793"},"reference-count":32,"publisher":"MDPI AG","issue":"9","license":[{"start":{"date-parts":[[2026,8,26]],"date-time":"2026-08-26T00:00:00Z","timestamp":1787702400000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Biomolecules"],"abstract":"<jats:p>Diabetes mellitus (DM) is a chronic metabolic disease characterized by hyperglycemia, and the diaphragm\u2014the primary respiratory muscle\u2014is adversely affected by this diabetic process. The aim of this study is to investigate the effects of zinc sulfate (ZnSO4) treatment on diaphragm muscle contractile dynamics, calcium homeostasis, apoptosis, and fibrosis in an 18-month-old female Type 2 diabetic rat model. Thirty-two 18-month-old female Wistar rats were randomly divided into four groups: Control (CON), CON + ZnSO4, Diabetes Mellitus (DM), and DM + ZnSO4. The DM model was induced by a high-fat diet and administration of 30 mg\/kg streptozotocin (STZ); after the disease was confirmed, ZnSO4 was administered intraperitoneally at a daily dose of 10 mg\/kg to the treatment groups. The mechanical functions of the diaphragm muscle were evaluated using a post-rest potentiation protocol in an isolated organ bath; qPCR analyses (Caspase-3, TGF-\u03b21, SERCA2a) were performed to investigate cellular apoptosis, fibrosis, and calcium regulation. Compared with the CON group, the DM group exhibited a severe ~90% reduction in diaphragmatic contraction force (CF) and a ~97% decline in maximal contraction\/relaxation velocities (\u00b1dF\/dtmax) (p &lt; 0.0001), which strongly correlated with a 30% suppression of SERCA2a gene expression (p &lt; 0.01). Concomitantly, apoptotic Caspase-3 (~2.6-fold) and profibrotic TGF-\u03b21 (~3.1-fold) mRNA levels were significantly elevated (p &lt; 0.0001). In the DM + ZnSO4 group, daily zinc treatment (10 mg\/kg\/day, i.p. for 6 weeks, initiated 4 weeks after diabetes confirmation) did not reverse the elevated Caspase-3 and TGF-\u03b21 expressions (p &gt; 0.05). However, SERCA2a expression was fully preserved back to control levels (p &lt; 0.05 vs. DM), leading to a substantial ~3-fold improvement in CF and velocities (p &lt; 0.05 to p &lt; 0.0001 vs. DM). On the other hand, the healthy CON + ZnSO4 group exhibited a physiological slowing of contractility (~53% decrease in CF), without histological damage, likely due to a competitive antagonism between excess divalent zinc (Zn2+) and calcium (Ca2+) on myofilaments. Although zinc cannot reverse the structural apoptotic and fibrotic remodeling in the aged diabetic diaphragm, it successfully rescues functional contractility by preserving SERCA2a transcriptional expression.<\/jats:p>","DOI":"10.3390\/biom16091236","type":"journal-article","created":{"date-parts":[[2026,8,26]],"date-time":"2026-08-26T16:54:42Z","timestamp":1787763282000},"page":"1236","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["Zinc Supplementation Sustains Diaphragm Contractility and Preserves SERCA2a Expression in Aged Female Rats with Type 2 Diabetes"],"prefix":"10.3390","volume":"16","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-4816-830X","authenticated-orcid":false,"given":"Omer","family":"Unal","sequence":"first","affiliation":[{"name":"Department of Physiology, Faculty of Medicine, Samsun University, Samsun 55080, T\u00fcrkiye"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-7750-482X","authenticated-orcid":false,"given":"Nilufer","family":"Akgun-Unal","sequence":"additional","affiliation":[{"name":"Department of Biophysics, Faculty of Medicine, Ondokuz Mayis University, Samsun 55139, T\u00fcrkiye"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2026,8,26]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"28","DOI":"10.1016\/j.clnesp.2022.08.003","article-title":"Effects of zinc supplementation on glycemic control and oxidative stress in experimental diabetes: A systematic review","volume":"51","author":"Martins","year":"2022","journal-title":"Clin. Nutr. ESPEN"},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"145","DOI":"10.1007\/s12011-019-01902-4","article-title":"Zinc Deficiency Promoted Fibrosis via ROS and TIMP\/MMPs in the Myocardium of Mice","volume":"196","author":"Cao","year":"2020","journal-title":"Biol. Trace Elem. Res."},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"116694","DOI":"10.1016\/j.taap.2023.116694","article-title":"Diabetic cardiomyopathy\u2014Zinc preventive and therapeutic potentials by its anti-oxidative stress and sensitizing insulin signaling pathways","volume":"477","author":"Cai","year":"2023","journal-title":"Toxicol. Appl. Pharmacol."},{"key":"ref_4","doi-asserted-by":"crossref","unstructured":"Gembillo, G., Visconti, L., Giuffrida, A.E., Labbozzetta, V., Peritore, L., Lipari, A., Calabrese, V., Piccoli, G.B., Torreggiani, M., and Siligato, R. (2022). Role of Zinc in Diabetic Kidney Disease. Nutrients, 14.","DOI":"10.3390\/nu14071353"},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"1280","DOI":"10.1177\/1535370220931038","article-title":"Protective effect of exogenous hydrogen sulfide on diaphragm muscle fibrosis in streptozotocin-induced diabetic rats","volume":"245","author":"Yang","year":"2020","journal-title":"Exp. Biol. Med."},{"key":"ref_6","doi-asserted-by":"crossref","unstructured":"Mart\u00ednez-S\u00e1nchez, J.E., C\u00e1rdenas, Y., Trujillo, X., R\u00edos-Silva, M., D\u00edaz-Reval, M.I., Bricio-Barrios, J.A., Mu\u00f1iz, J., Alcaraz-Siqueiros, J., and Huerta, M. (2024). Increased Frequency of Giant Miniature End-Plate Potentials at the Neuromuscular Junction in Diabetic Rats. Biomedicines, 12.","DOI":"10.3390\/biomedicines12010068"},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"820","DOI":"10.58600\/eurjther1912","article-title":"The Effect of MitoTEMPO on Rat Diaphragm Muscle Contraction Parameters in an Experimental Diabetes Model Induced with Streptozotocin","volume":"29","author":"Ahmet","year":"2023","journal-title":"Eur. J. Ther."},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"6662418","DOI":"10.1155\/2021\/6662418","article-title":"Zinc Supplementation Prevented Type 2 Diabetes-Induced Liver Injury Mediated by the Nrf2-MT Antioxidative Pathway","volume":"2021","author":"Yu","year":"2021","journal-title":"J. Diabetes Res."},{"key":"ref_9","doi-asserted-by":"crossref","unstructured":"Li, J., Li, X., Wang, Y., Meng, L., and Cui, W. (2024). Zinc: A potential star for regulating peritoneal fibrosis. Front. Pharmacol., 15.","DOI":"10.3389\/fphar.2024.1436864"},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"e13604","DOI":"10.1111\/jfbc.13604","article-title":"Potential health benefits of zinc supplementation for the management of COVID-19 pandemic","volume":"45","author":"Oyagbemi","year":"2021","journal-title":"J. Food Biochem."},{"key":"ref_11","first-page":"5925","article-title":"Role of Some Micronutrients in the Healing Process of Diabetic Ulcers","volume":"30","author":"Hristova","year":"2024","journal-title":"J. IMAB-Annu. Proceeding (Sci. Pap.)"},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"2083","DOI":"10.1007\/s12011-025-04803-x","article-title":"Zinc Attenuates Cadmium and High-Fat Diet-Induced Cardiomyopathy by Enhancing Metallothionein-Mediated Cardiac Protection","volume":"204","author":"Liang","year":"2026","journal-title":"Biol. Trace Elem. Res."},{"key":"ref_13","doi-asserted-by":"crossref","unstructured":"Akgun-Unal, N., Unal, O., Altun, G., Gulbahce-Mutlu, E., Akkoca, A., and Ayyildiz, M. (2026). The Effect of Zinc Sulfate Treatment on Diabetic Cardiomyopathy in an Aged Female Rat Model of Type 2 Diabetes. Nutrients, 18.","DOI":"10.3390\/nu18122005"},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"1373","DOI":"10.2147\/DDDT.S157803","article-title":"Antihyperglycemic and anti-inflammatory effects of fermented food paste in high-fat diet and streptozotocin-challenged mice","volume":"12","author":"Zulkawi","year":"2018","journal-title":"Drug Des. Dev. Ther."},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"20801","DOI":"10.1021\/acs.jafc.3c04665","article-title":"Amelioration of Type 2 Diabetes Using Four Strains of Lactobacillus Probiotics: Effects on Gut Microbiota Reconstitution-Mediated Regulation of Glucose Homeostasis, Inflammation, and Oxidative Stress in Mice","volume":"71","author":"Song","year":"2023","journal-title":"J. Agric. Food Chem."},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"100398","DOI":"10.1016\/j.modpat.2023.100398","article-title":"Deep Learning-Based H-Score Quantification of Immunohistochemistry-Stained Images","volume":"37","author":"Wen","year":"2024","journal-title":"Mod. Pathol."},{"key":"ref_17","doi-asserted-by":"crossref","first-page":"402","DOI":"10.1006\/meth.2001.1262","article-title":"Analysis of relative gene expression data using real-time quantitative PCR and the 2(-Delta Delta C(T)) Method","volume":"25","author":"Livak","year":"2001","journal-title":"Methods"},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"981","DOI":"10.1113\/JP280899","article-title":"Abnormal skeletal muscle blood flow, contractile mechanics and fibre morphology in a rat model of obese-HFpEF","volume":"599","author":"Tickle","year":"2021","journal-title":"J. Physiol."},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"490","DOI":"10.1139\/cjpp-2019-0609","article-title":"Thirty-day experimental diabetes impairs contractility and increases fatigue resistance in rat diaphragm muscle associated with increased anti-oxidative activity","volume":"98","author":"Peixoto","year":"2020","journal-title":"Can. J. Physiol. Pharmacol."},{"key":"ref_20","doi-asserted-by":"crossref","first-page":"67","DOI":"10.5455\/javar.2026.m1011","article-title":"Morphological and structural alterations in skeletal muscle of STZ-induced diabetic rats revealed by light and electron microscopy","volume":"13","author":"Gopalan","year":"2026","journal-title":"J. Adv. Vet. Anim. Res."},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"1443","DOI":"10.1007\/s00592-024-02311-3","article-title":"Comparative study on muscle function in two different streptozotocin-induced diabetic models","volume":"61","author":"Aisyah","year":"2024","journal-title":"Acta Diabetol."},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"582","DOI":"10.17305\/bb.2023.9843","article-title":"Skeletal muscle myosin heavy chain expression and 3D capillary network changes in streptozotocin-induced diabetic female mice","volume":"24","author":"Umek","year":"2024","journal-title":"Biomol. Biomed."},{"key":"ref_23","doi-asserted-by":"crossref","first-page":"27","DOI":"10.3109\/15376516.2012.735277","article-title":"The role of zinc in the prevention of diabetic cardiomyopathy and nephropathy","volume":"23","author":"Li","year":"2013","journal-title":"Toxicol. Mech. Methods"},{"key":"ref_24","doi-asserted-by":"crossref","first-page":"R88","DOI":"10.1186\/cc13855","article-title":"Hyperglycemia-induced diaphragm weakness is mediated by oxidative stress","volume":"18","author":"Callahan","year":"2014","journal-title":"Crit. Care"},{"key":"ref_25","doi-asserted-by":"crossref","first-page":"101529","DOI":"10.1016\/j.redox.2020.101529","article-title":"Zinc at the crossroads of exercise and proteostasis","volume":"35","author":"Parsons","year":"2020","journal-title":"Redox Biol."},{"key":"ref_26","doi-asserted-by":"crossref","unstructured":"Norouzi, S., Adulcikas, J., Sohal, S.S., and Myers, S. (2018). Zinc stimulates glucose oxidation and glycemic control by modulating the insulin signaling pathway in human and mouse skeletal muscle cell lines. PLoS ONE, 13.","DOI":"10.1371\/journal.pone.0191727"},{"key":"ref_27","doi-asserted-by":"crossref","first-page":"752","DOI":"10.1007\/s12035-026-06054-w","article-title":"Resveratrol Ameliorates PTZ-Induced Seizure Activity and Diaphragm Muscle Dysfunction by Regulating Calcium Handling and Apoptotic Pathways in Rats","volume":"63","author":"Akkoca","year":"2026","journal-title":"Mol. Neurobiol."},{"key":"ref_28","doi-asserted-by":"crossref","unstructured":"Kho, C. (2023). Targeting calcium regulators as therapy for heart failure: Focus on the sarcoplasmic reticulum Ca-ATPase pump. Front. Cardiovasc. Med., 10.","DOI":"10.3389\/fcvm.2023.1185261"},{"key":"ref_29","doi-asserted-by":"crossref","first-page":"18365","DOI":"10.1007\/s00210-026-05557-6","article-title":"Epilepsy-induced heart damage and sudep risk: Ion channelopathies, calcium homeostasis, and the therapeutic potential of resveratrol","volume":"399","author":"Unal","year":"2026","journal-title":"Naunyn-Schmiedeberg\u2019s Arch. Pharmacol."},{"key":"ref_30","first-page":"655","article-title":"Zinc supplementation inhibits the high glucose-induced EMT of peritoneal mesothelial cells by activating the Nrf2 antioxidant pathway","volume":"20","author":"Gao","year":"2019","journal-title":"Mol. Med. Rep."},{"key":"ref_31","doi-asserted-by":"crossref","first-page":"1","DOI":"10.1016\/j.jtemb.2017.03.006","article-title":"The beneficial effects of zinc on diabetes-induced kidney damage in murine rodent model of type 1 diabetes mellitus","volume":"42","author":"Yang","year":"2017","journal-title":"J. Trace Elem. Med. Biol."},{"key":"ref_32","doi-asserted-by":"crossref","first-page":"17599","DOI":"10.1074\/jbc.M115.661280","article-title":"Intracellular Zinc Modulates Cardiac Ryanodine Receptor-mediated Calcium Release","volume":"290","author":"Woodier","year":"2015","journal-title":"J. Biol. Chem."}],"container-title":["Biomolecules"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/2218-273X\/16\/9\/1236\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2026,8,27]],"date-time":"2026-08-27T09:13:50Z","timestamp":1787822030000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/2218-273X\/16\/9\/1236"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2026,8,26]]},"references-count":32,"journal-issue":{"issue":"9","published-online":{"date-parts":[[2026,9]]}},"alternative-id":["biom16091236"],"URL":"https:\/\/doi.org\/10.3390\/biom16091236","relation":{},"ISSN":["2218-273X"],"issn-type":[{"value":"2218-273X","type":"electronic"}],"subject":[],"published":{"date-parts":[[2026,8,26]]}}}