title: Exogenous leptin administered intramuscularly induces sex hormone disorder and Ca loss via downregulation of Gnrh and PI3K expression.
abstract: Obesity is a public health problem that increases the risk of metabolic disease, infertility, and other chronic health problems. The present study aimed to develop a new rat model for sex hormone disorder with overweight and Ca loss by intramuscular injection of exogenous leptin (LEP). Thirty female Sprague-Dawley (SD) rats (40 days old) were injected thrice intramuscularly with LEP or keyhole limpet hemocyanin immunogen. The following analyses were performed to determine the development of appetite, overweight, reproductive related-hormones, and calcium (Ca)/phosphorus (Pi) in SD rats: measurement of Lee's index, body weight, food intake; serum Ca, Pi, and hormone tests by enzyme-linked immunosorbent analysis; histological analysis of abdominal fat; real-time polymerase chain reaction analysis of neuropeptide Y, pro-opiomelanocortin, gonadotropin-releasing hormone (Gnrh) mRNA, and gonadotropin-releasing hormone receptor (Gnrhr) mRNA expression; and western blotting analysis of enzyme phosphatidylinositol-3-kinase (PI3K). Rats injected with LEP immunogen displayed significantly increased body weight, food intake, Lee's index, serum LEP, serum cortisol, fat deposition in the abdomen, and decreased hormones including follicle stimulating hormone, luteinizing hormone, estradiol, cholecystokinin, and Ca. Exogenous LEP administered intramuscularly also downregulate Gnrh and PI3K. In conclusion, exogenous LEP administered intramuscularly is a novel animal model for sex hormones disorder with overweight and Ca loss in SD rats. The downregulation of PI3K and Gnrh may be involved in the development of this animal model.
authors.affiliation: Department of Laboratory Animal Center, Southern Medical University, 1023 Guangzhou North Road, 510515 Guangzhou, Guangdong, P.R. China.
authors.forename: Lihong
authors.initials: L
authors.lastname: Wu
authors.forename: Wen
authors.initials: W
authors.lastname: Liu
authors.forename: Nashun
authors.initials: N
authors.lastname: Bayaer
authors.forename: Weiwang
authors.initials: W
authors.lastname: Gu
authors.forename: Jieli
authors.initials: J
authors.lastname: Song
mesh_terms: D000818:Animals; D002118:Calcium / Q000378:metabolism*; D004195:Disease Models, Animal; D015536:Down-Regulation / Q000187:drug effects*; D005260:Female; D015870:Gene Expression / Q000187:drug effects*; D012739:Gonadal Steroid Hormones / Q000378:metabolism*; D007987:Gonadotropin-Releasing Hormone / Q000235:genetics* / Q000378:metabolism*; D007273:Injections, Intramuscular; D020738:Leptin / Q000008:administration & dosage* / Q000009:adverse effects* / Q000097:blood; D050177:Overweight / Q000139:chemically induced*; D019869:Phosphatidylinositol 3-Kinases / Q000235:genetics* / Q000378:metabolism*; D017207:Rats, Sprague-Dawley
chemical_list: D012739:Gonadal Steroid Hormones; D020738:Leptin; D007987:Gonadotropin-Releasing Hormone; D019869:Phosphatidylinositol 3-Kinases; D002118:Calcium