{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2025,11,12]],"date-time":"2025-11-12T11:09:59Z","timestamp":1762945799727,"version":"3.45.0"},"reference-count":89,"publisher":"MDPI AG","issue":"22","license":[{"start":{"date-parts":[[2025,11,12]],"date-time":"2025-11-12T00:00:00Z","timestamp":1762905600000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"Natural Science Foundation of Jilin Provincial Department of Science and Technology","award":["20240101232JC"],"award-info":[{"award-number":["20240101232JC"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Nutrients"],"abstract":"<jats:p>Background\/Objectives: Copper is an essential trace element for physiological processes related to reproduction, but its impact on the hypothalamic\u2013pituitary\u2013ovarian (HPOA) axis and its specific mechanism remain unclear. Methods: In vivo study: 21-day-old female Sprague Dawley (SD) rats were randomly assigned to five groups (n = 10 per group), with all groups fed a basal diet and supplemented with CuSO4\u00b75H2O to achieve copper ion concentrations of 0, 15, 30, 45, or 60 mg\/kg in the diet. During the second phase of proestrus, blood samples, hypothalamic tissues, pituitary tissues, and ovarian tissues were collected. In vitro study: Primary mixed hypothalamic neurons were isolated and cultured from fetal SD rats on embryonic day 17. After identification by NSE immunofluorescence staining, six copper ion concentration groups (0, 15.6, 31.2, 46.8, 62.4, and 78 \u03bcmol\/L) were established. The optimal copper concentration for cell viability and GnRH secretion was screened using CCK-8 assay (Sangon, Shanghai, China) and ELISA (Mlbio, Shanghai, China). On this basis, the cells were treated with different concentrations of PKC agonist (PMA) and PKC inhibitor (chelerythrine). Cell viability was evaluated by CCK-8 assay, the expression level of PKC was detected by Western blot, and the optimal concentration with no obvious toxicity was selected for subsequent mechanism research. Results: Dietary copper dose-dependently regulated rat puberty onset; the 45 mg\/kg copper group had the earliest onset, and showed significantly increased levels of reproduction-related hormones (GnRH, FSH, LH, E2) in serum and HPOA axis. Hypothalamic transcriptomics revealed significantly enriched GnRH signaling pathways and GABAergic synaptic pathways. Mechanistically, this copper dose upregulated hypothalamic KISS-1, GPR54, and PKC (mRNA\/protein), and downregulated GABA\/GABA-R. Adding 46.8 \u03bcmol\/L copper (as Cu2+, equivalent to optimal in vivo level) could activate the KISS-1\/GPR54-GnRH system in hypothalamic neurons; regulating PKC activity could synchronously affect the expression of KISS-1, GPR54, GnRH, and GABA\/GABA-R, with additional copper enhancing this effect in vitro experiments. Conclusions: This study demonstrates for the first time that dietary copper at 45 mg\/kg promotes puberty onset in SD rats. The mechanism involves activation of the hypothalamic PKC pathway, which inhibits GABAergic neurotransmission while activating the KISS-1\/GPR54-GnRH system, thereby enhancing HPOA axis activity and gonadotropin secretion.<\/jats:p>","DOI":"10.3390\/nu17223534","type":"journal-article","created":{"date-parts":[[2025,11,12]],"date-time":"2025-11-12T10:56:47Z","timestamp":1762945007000},"page":"3534","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["Dietary Copper on the Onset of Puberty in Rats: Possible Mechanism"],"prefix":"10.3390","volume":"17","author":[{"given":"Rui","family":"Sun","sequence":"first","affiliation":[{"name":"College of Animal Science and Technology, Jilin Agricultural University, Changchun 130118, China"},{"name":"Key Laboratory of Animal Production, Product Quality and Security, Ministry of Education, Changchun 130118, China"},{"name":"Jilin Provincial Key Laboratory of Animal Nutrition and Feed Science, Changchun 130118, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Zhongshen","family":"Wang","sequence":"additional","affiliation":[{"name":"College of Animal Science and Technology, Jilin Agricultural University, Changchun 130118, China"},{"name":"Key Laboratory of Animal Production, Product Quality and Security, Ministry of Education, Changchun 130118, China"},{"name":"Jilin Provincial Key Laboratory of Animal Nutrition and Feed Science, Changchun 130118, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Cheng","family":"Li","sequence":"additional","affiliation":[{"name":"College of Animal Science and Technology, Jilin Agricultural University, Changchun 130118, China"},{"name":"Key Laboratory of Animal Production, Product Quality and Security, Ministry of Education, Changchun 130118, China"},{"name":"Jilin Provincial Key Laboratory of Animal Nutrition and Feed Science, Changchun 130118, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Meng","family":"Li","sequence":"additional","affiliation":[{"name":"College of Animal Science and Technology, Jilin Agricultural University, Changchun 130118, China"},{"name":"Key Laboratory of Animal Production, Product Quality and Security, Ministry of Education, Changchun 130118, China"},{"name":"Jilin Provincial Key Laboratory of Animal Nutrition and Feed Science, Changchun 130118, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Wenyan","family":"Yang","sequence":"additional","affiliation":[{"name":"College of Animal Science and Technology, Jilin Agricultural University, Changchun 130118, China"},{"name":"Key Laboratory of Animal Production, Product Quality and Security, Ministry of Education, Changchun 130118, China"},{"name":"Jilin Provincial Key Laboratory of Animal Nutrition and Feed Science, Changchun 130118, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Lianyu","family":"Yang","sequence":"additional","affiliation":[{"name":"College of Animal Science and Technology, Jilin Agricultural University, Changchun 130118, China"},{"name":"Key Laboratory of Animal Production, Product Quality and Security, Ministry of Education, Changchun 130118, China"},{"name":"Jilin Provincial Key Laboratory of Animal Nutrition and Feed Science, Changchun 130118, China"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1968","published-online":{"date-parts":[[2025,11,12]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"741","DOI":"10.1016\/j.ecl.2020.08.002","article-title":"Delayed and Precocious Puberty\u2013Genetic Underpinnings and Treatments","volume":"49","author":"Gohil","year":"2020","journal-title":"Endocrinol. 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