High fat diet altered the mechanism of energy homeostasis induced by nicotine and withdrawal in C57BL/6 mice.
Nicotine treatment has known to produce an inverse relationship between body weight and food intake in rodents. Present study determined the effect of repeated treatment with nicotine and withdrawal in control and obese mice, on: (1) body weight, caloric intake and energy expenditure; (2) hypothalamic neuropeptides mRNA expression; and (3) serum leptin. 21-week-old C57BL/6 mice (n = 65) received nicotine (3.0 mg/kg/day; 2 weeks) and saline (1 ml/kg/day; 2 weeks) subcutaneously. Animals were given either a normal-fat (10% kcal from fat, NF) or a high-fat diet (45% kcal from fat, HF) from the 12th week to 25th week. While, nicotine treatment for 14 days induced an increase in hypothalamic agouti-related protein, cocaine- and amphetamine- regulated transcript, pro-opiomelanocortin mRNA expressions, nicotine also produced a reducing effect in body weight gain and leptin concentration in NF mice. High-fat diet induced obese mice showed a blunted hypothalamic and leptin response to nicotine. Remarkable weight loss in obese mice was mediated not just by decreasing caloric intake, but also by increasing total energy expenditure (EE). During nicotine withdrawal period, weight gain occurred in NF and HF groups, which was ascribed to a decrease in EE rather than changes in caloric intake. Hypothalamic AgRP might play a role for maintaining energy balance under the nicotine-induced negative energy status.
Hur
Young-Na
YN
Department of Pharmacology, Korea University College of Medicine, Seoul, 136-705, Korea.
Hong
Gee-Hyun
GH
Choi
Sang-Hyun
SH
Shin
Kyung-Ho
KH
Chun
Boe-Gwun
BG
D000818:Animals; D004041:Dietary Fats / Q000008:administration & dosage; D004734:Energy Metabolism / Q000187:drug effects; D007031:Hypothalamus / Q000187:drug effects / Q000378:metabolism* / Q000473:pathology; D020738:Leptin / Q000097:blood; D051379:Mice; D008810:Mice, Inbred C57BL; D009538:Nicotine / Q000008:administration & dosage* / Q000009:adverse effects; D009765:Obesity / Q000097:blood / Q000139:chemically induced / Q000378:metabolism* / Q000473:pathology; D011333:Pro-Opiomelanocortin / Q000096:biosynthesis* / Q000235:genetics
D004041:Dietary Fats; D020738:Leptin; D011333:Pro-Opiomelanocortin; D009538:Nicotine