Time-course changes of hormones and cytokines by lipopolysaccharide and its relation with anorexia.
We assessed the time course effects of lipopolysaccaride (LPS) on food intake, cytokines, and hormones in rats and evaluated the relation between LPS-induced anorexia and its possible causative factors. Food intake was reduced 2 h after LPS injection (500 microg/kg, intraperitoneally) and remained decreased for 24 h. Plasma TNF-alpha and IL-6 levels increased by LPS administration at 0.5 and 2 h, and at 2 and 4 h, respectively. Plasma leptin and glucose levels were elevated at 8 and 16 h, and insulin levels were elevated at 2, 4, 8, and 16 h in the LPS-injected group, as compared to the counterpart controls. IL-6 levels in the CSF were elevated at 2 and 4 h. Hypothalamic cytokines tended to increase as early as 0.5 h after LPS injection and remained increased until 16 h. LPS-induced anorexia was attenuated in insulin-deficient STZ rats and was abolished by insulin treatment. The hypothalamic expression of NPY, a target of insulin's anorexic effect, was decreased 2 h after LPS administration, and central NPY injection (3 nM) prevented LPS-induced anorexia. In conclusion, cytokines, insulin, and leptin levels evidence different time courses by LPS administration. In LPS-induced anorexia, insulin may constitute a newly found causative factor, whereas leptin appears to be uninvolved in an early period in rats.
Kim
Yong-Woon
YW
Department of Physiology, College of Medicine, Yeungnam University, Daegu, Korea.
Kim
Keon-Ho
KH
Ahn
Dong-Kuk
DK
Kim
Hee-Sun
HS
Kim
Jong-Yeon
JY
Lee
Dong Chul
DC
Park
So-Young
SY
D000818:Animals; D000855:Anorexia / Q000139:chemically induced / Q000378:metabolism*; D016207:Cytokines / Q000037:antagonists & inhibitors / Q000378:metabolism*; D004435:Eating / Q000187:drug effects; D007004:Hypoglycemic Agents / Q000378:metabolism / Q000494:pharmacology; D007274:Injections, Intraperitoneal; D007328:Insulin / Q000378:metabolism* / Q000494:pharmacology; D015850:Interleukin-6 / Q000097:blood / Q000134:cerebrospinal fluid; D020738:Leptin / Q000378:metabolism*; D008070:Lipopolysaccharides / Q000008:administration & dosage / Q000493:pharmacokinetics*; D008297:Male; D009478:Neuropeptide Y / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D013997:Time Factors; D014409:Tumor Necrosis Factor-alpha / Q000097:blood
D016207:Cytokines; D007004:Hypoglycemic Agents; D007328:Insulin; D015850:Interleukin-6; D020738:Leptin; D008070:Lipopolysaccharides; D009478:Neuropeptide Y; D014409:Tumor Necrosis Factor-alpha