Lipopolysaccharide (LPS) stimulates adipokine and socs3 gene expression in mouse brain and pituitary gland in vivo, and in N-1 hypothalamic neurons in vitro.
Adipokines that modulate metabolic and inflammatory responses, such as resistin (rstn) and fasting-induced adipose factor (fiaf), are also expressed in mouse brain and pituitary gland. Since lipopolysaccharide (LPS)-induced endotoxinemia provokes an anorectic response via a hypothalamic-dependent mechanism we hypothesized that LPS would also modify hypothalamic adipokine expression. Challenging male CD-1 mice with LPS (5 mg/kg; s.c.) significantly reduced bodyweight (24 h) and realtime RT-PCR revealed time- and tissue-dependent increases in rstn, fiaf and suppressor of cytokine signaling-3 (socs-3) mRNA in hypothalamic, pituitary, cortical and adipose tissues. Gene expression was rapidly increased (3-6 h) in the hypothalamus and pituitary, but returned to normal within 24 h. In contrast, with the exception of rstn in fat, the expression of target genes remained elevated in cortex and visceral fat at 24 h post-injection. In order to more specifically examine the hypothalamic response to LPS we investigated its effects directly on N-1 hypothalamic neurons in vitro. LPS (25 microg/mL; 3 h) had no effect on rstn mRNA, but significantly stimulated fiaf and socs-3 expression. Although various toll-like receptor 4 (TLR4) antagonists (parthenolide, PD098059, and SB202190) did not prevent the LPS-induced increases in fiaf and socs-3, they did partially attenuate its stimulatory effects. We conclude that LPS treatment increases the expression of central, and possibly neuronal, adipokine genes which may influence local tissue repair and function, but could also have downstream consequences on the hypothalamic control of appetite and energy metabolism following an inflammatory insult.
Brown
Russell
R
Department of Obstetrics and Gynaecology, Faculty of Medicine, Dalhousie University, c/o IWK Health Centre, Nova Scotia, Canada. Brownre@dal.ca
Imran
Syed A
SA
Wilkinson
Michael
M
D054392:Adipokines / Q000235:genetics*; D000273:Adipose Tissue / Q000187:drug effects / Q000378:metabolism / Q000503:physiopathology; D000075803:Angiopoietin-Like Protein 4; D042682:Angiopoietins / Q000235:genetics; D000818:Animals; D001835:Body Weight / Q000187:drug effects / Q000502:physiology; D001921:Brain / Q000187:drug effects / Q000378:metabolism* / Q000503:physiopathology; D002460:Cell Line; D002478:Cells, Cultured; D002540:Cerebral Cortex / Q000187:drug effects / Q000378:metabolism / Q000503:physiopathology; D004660:Encephalitis / Q000139:chemically induced / Q000378:metabolism* / Q000503:physiopathology; D005786:Gene Expression Regulation / Q000187:drug effects; D007031:Hypothalamus / Q000187:drug effects / Q000378:metabolism / Q000503:physiopathology; D018836:Inflammation Mediators / Q000494:pharmacology; D008070:Lipopolysaccharides / Q000494:pharmacology; D008297:Male; D051379:Mice; D009474:Neurons / Q000187:drug effects / Q000378:metabolism; D010902:Pituitary Gland / Q000187:drug effects / Q000378:metabolism* / Q000503:physiopathology; D012333:RNA, Messenger / Q000187:drug effects / Q000378:metabolism; D052243:Resistin / Q000235:genetics; D000071223:Suppressor of Cytokine Signaling 3 Protein; D050826:Suppressor of Cytokine Signaling Proteins / Q000235:genetics*; D051197:Toll-Like Receptor 4 / Q000037:antagonists & inhibitors / Q000378:metabolism
D054392:Adipokines; D000075803:Angiopoietin-Like Protein 4; D042682:Angiopoietins; C407088:Angptl4 protein, mouse; D018836:Inflammation Mediators; D008070:Lipopolysaccharides; D012333:RNA, Messenger; D052243:Resistin; C499623:Retn protein, mouse; C491411:Socs3 protein, mouse; D000071223:Suppressor of Cytokine Signaling 3 Protein; D050826:Suppressor of Cytokine Signaling Proteins; C493487:Tlr4 protein, mouse; D051197:Toll-Like Receptor 4