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Wu L, Chen G, Liu W, Yang X, Gao J, Huang L, Guan H, Li Z, Zheng Z, Li M, Gu W, Ge L. Intramuscular injection of exogenous leptin induces adiposity, glucose intolerance and fatty liver by repressing the JAK2-STAT3/PI3K pathway in a rat model. Gen Comp Endocrinol 2017; 252:88-96. [PMID: 28242305 DOI: 10.1016/j.ygcen.2017.02.012] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/29/2016] [Revised: 02/20/2017] [Accepted: 02/23/2017] [Indexed: 12/23/2022]
Abstract
Obesity, diabetes and fatty liver disease are extremely common in leptin-resistant patients. Dysfunction of leptin or its receptor is associated with obesity. The present study aimed to assess the effects of intramuscular injection of exogenous leptin or its receptor on fat deposition and leptin-insulin feedback regulation. Forty-five 40-day old female Sprague Dawley (SD) rats were injected thrice with leptin or its receptor intramuscularly. Adiposity and fat deposition were assessed by assessing the Lee's index, body weight, food intake, and total cholesterol, high density lipoprotein, low density lipoprotein, and triglyceride levels, as well as histological properties (liver and adipose tissue). Serum glucose, leptin, and insulin amounts were evaluated, and glucose tolerance assessed to monitor glucose metabolism in SD rats; pancreas specimens were analyzed immunohistochemically. Hypothalamic phosphorylated Janus kinase 2 (p-JAK2), phosphorylated signal transducer and activator of transcription 3 (p-STAT3), and phosphatidylinositol-3-kinase (PI3K) signaling, and hepatic sterol regulatory element binding protein-1 (SREBP-1) were qualified by Western blotting. Leptin receptor immunogen reduced fat deposition, increased appetite, and lowered serum leptin levels, enhancing STAT3 signaling in hypothalamus and down-regulating hepatic SREBP-1. In contrast, SD rats administered leptin immunogen displayed significantly increased body weight and fat deposition, with up-regulated SREBP-1, indicating adiposity occurrence. SD rats administered leptin immunogen also showed glucose intolerance, β- cell reduction in the pancreas, and deregulation of JAK2-STAT3/PI3K signaling, indicating that Lep rats were at risk of diabetes. In conclusion, intramuscular injection of exogenous leptin or its receptor, a novel rat model approach, can be used in obesity pathogenesis and therapeutic studies.
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Affiliation(s)
- Lihong Wu
- Key Laboratory of Oral Medicine, Guangzhou Institure of Oral Disease, Stomatology Hospital of Guangzhou Medical University, Guangzhou 510140, China; Center of Emphasis in Infectious Diseases, Department of Biomedical Sciences, Paul L. Foster School of Medicine, Texas Tech University Health Sciences Center El Paso, El Paso, TX 79905, USA
| | - Guoxiong Chen
- First Department of Orthopedics, The Affiliated Nanhai Hospital of Southern Medical University, Foshan 528200, China
| | - Wen Liu
- Department of Laboratory Animal Center, Southern Medical University, Guangzhou 510515, China
| | - Xuechao Yang
- Key Laboratory of Oral Medicine, Guangzhou Institure of Oral Disease, Stomatology Hospital of Guangzhou Medical University, Guangzhou 510140, China
| | - Jie Gao
- Key Laboratory of Oral Medicine, Guangzhou Institure of Oral Disease, Stomatology Hospital of Guangzhou Medical University, Guangzhou 510140, China
| | - Liwen Huang
- Key Laboratory of Oral Medicine, Guangzhou Institure of Oral Disease, Stomatology Hospital of Guangzhou Medical University, Guangzhou 510140, China
| | - Hongbing Guan
- Key Laboratory of Oral Medicine, Guangzhou Institure of Oral Disease, Stomatology Hospital of Guangzhou Medical University, Guangzhou 510140, China
| | - Zhengmao Li
- Key Laboratory of Oral Medicine, Guangzhou Institure of Oral Disease, Stomatology Hospital of Guangzhou Medical University, Guangzhou 510140, China
| | - Zhichao Zheng
- Key Laboratory of Oral Medicine, Guangzhou Institure of Oral Disease, Stomatology Hospital of Guangzhou Medical University, Guangzhou 510140, China
| | - Meiling Li
- Key Laboratory of Oral Medicine, Guangzhou Institure of Oral Disease, Stomatology Hospital of Guangzhou Medical University, Guangzhou 510140, China
| | - Weiwang Gu
- Department of Laboratory Animal Center, Southern Medical University, Guangzhou 510515, China; Department of Laboratory Animal Science, Songshan Lake Pearl Laboratory Animal Sci. & Tech. Co., Ltd., Dongguan 523808, China.
| | - Linhu Ge
- Key Laboratory of Oral Medicine, Guangzhou Institure of Oral Disease, Stomatology Hospital of Guangzhou Medical University, Guangzhou 510140, China.
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Lei MM, Wu SQ, Shao XB, Li XW, Chen Z, Ying SJ, Shi ZD. Creating leptin-like biofunctions by active immunization against chicken leptin receptor in growing chickens. Domest Anim Endocrinol 2015; 50:55-64. [PMID: 25447880 DOI: 10.1016/j.domaniend.2014.09.001] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/29/2014] [Revised: 09/01/2014] [Accepted: 09/04/2014] [Indexed: 12/19/2022]
Abstract
In this study, immunization against chicken leptin receptor (cLEPR) extracellular domain (ECD) was applied to investigate leptin regulation and LEPR biofunction in growing chicken pullets. A recombinant protein (cLEPR ECD) based on the cLEPR complemenary DNA sequence corresponding to the 582nd to 796th amino acid residues of cLEPR mature peptide was prepared and used as antigen. Immunization against cLEPR ECD in growing chickens increased anti-cLEPR ECD antibody titers in blood, enhanced proportions of phosphorylated janus kinase 2 (JAK2) and served as signal transducer and activator of transcription 3 (STAT3) protein in liver tissue. Chicken live weight gain and abdominal fat mass were significantly decreased (P < 0.05), but feed intake was stimulated by cLEPR ECD immunization (P < 0.05). The treatment also upregulated the gene expression levels of lepR, AMP-activated protein kinase (AMPK), acetyl CoA carboxylase-2 (ACC2), and uncoupling protein 3 (UCP3) in liver, abdominal fat, and breast muscle (P < 0.05) but decreased fasn expression levels (P < 0.01). Apart from that of lepR, the expression of appetite-regulating genes, such as orexigenic genes, agouti-related peptide (AgRP) and neuropeptide Y (NPY), were upregulated (P < 0.01), whereas the anorexigenic gene proopiomelanocortin (POMC) was downregulated in the hypothalamic tissue of cLEPR-immunized pullets (P < 0.01). Blood concentrations of metabolic molecules, such as glucose, triglycerides, and very-low-density lipoprotein, were significantly decreased in cLEPR-immunized pullets but those of cholesterol, high-density lipoprotein, and low-density lipoprotein increased. These results demonstrate that antibodies to membrane proximal cLEPR ECD enhance cLEPR signal transduction, which stimulates metabolism and reduces fat deposition in chickens.
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Affiliation(s)
- M M Lei
- Laboratory of Animal Breed Improvement and Reproduction, Institute of Animal Science, Jiangsu Academy of Agricultural Sciences, Nanjing, 210014, China
| | - S Q Wu
- College of Animal Sciences, South China Agricultural University, Guangzhou, 510642, China
| | - X B Shao
- Institute of Guagndong Province Poultry Technology, Guangzhou, 510520, China
| | - X W Li
- College of Animal Sciences, South China Agricultural University, Guangzhou, 510642, China
| | - Z Chen
- Laboratory of Animal Breed Improvement and Reproduction, Institute of Animal Science, Jiangsu Academy of Agricultural Sciences, Nanjing, 210014, China
| | - S J Ying
- Laboratory of Animal Breed Improvement and Reproduction, Institute of Animal Science, Jiangsu Academy of Agricultural Sciences, Nanjing, 210014, China
| | - Z D Shi
- Laboratory of Animal Breed Improvement and Reproduction, Institute of Animal Science, Jiangsu Academy of Agricultural Sciences, Nanjing, 210014, China.
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Li WL, Liu Y, Yu YC, Huang YM, Liang SD, Shi ZD. Prolactin plays a stimulatory role in ovarian follicular development and egg laying in chicken hens. Domest Anim Endocrinol 2011; 41:57-66. [PMID: 21600726 DOI: 10.1016/j.domaniend.2011.03.002] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/21/2010] [Revised: 03/25/2011] [Accepted: 03/28/2011] [Indexed: 11/16/2022]
Abstract
The aim of this study was to show a stimulatory role in ovarian follicle development by prolactin (PRL) in chicken hens. In experiment 1, anti-PRL antibodies were generated in hen plasma by intramuscular administrations of recombinant PRL antigen. Egg laying remained at levels lower (P < 0.05) in the PRL-immunized group than in the BSA-immunized group of hens, whereas development of incubation was depressed in the former but not the latter group. Throughout the experiment, plasma PRL concentrations were lower in the PRL-immunized hens than in non-incubating control hens; LH concentrations were similar between the PRL- and BSA-immunized hens until the end of the experiment when LH was lower in the BSA-immunized hens (P < 0.05). In experiment 2, anti-PRL receptor (PRLR) antibodies were raised in hens with the use of immunizations against recombinant PRLR extracellular domain. Immunization against PRLR initially increased the egg-laying rate when measured under the short photoperiod (12 h) but blocked the laying rate increase that occurred in the BSA-immunized control hens when the photoperiod was extended from 12 to 16 h. The development of incubation behavior was not affected by immunization against PRLR nor was plasma PRL or LH concentration. In experiment 3, when the egg-laying rate was depressed in PRL immunization hens, developmental speed of large white follicles was found to be slower than in the BSA-immunized control hens (P < 0.05). These results indicate that immunization against PRL slows down ovarian follicular development and reduces hen egg-laying performance, suggesting that PRL plays a stimulatory role in ovarian follicular development in chicken hens.
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Affiliation(s)
- W L Li
- Department of Animal Science, South China Agricultural University, Guangzhou, China
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