Nicotine induces uncoupling protein 1 in white adipose tissue of obese mice.
OBJECTIVE
To test the hypothesis that nicotine not only activates uncoupling protein1 (UCP1) in brown adipose tissue (BAT), but also induces UCP1 in white adipose tissue (WAT), which contributes to the mitigation of obesity in obese mice.


METHODS
Weights of the whole body, the gastrocnemius muscle, interscapular BAT and subcutaneous and retroperitoneal WAT, food intake and the mRNA and protein of UCP1 in these tissues were measured and immunohistochemistry using antiserum against UCP1 was also performed in obese yellow KK mice treated with nicotine for 6 months and control mice treated with physiological saline.


RESULTS
Obese mice treated with nicotine for 6 months, compared with those injected with saline, weighed significantly less (P < 0.01) and had smaller subcutaneous and retroperitoneal WAT pads (P < 0.01), while obese mice that received nicotine ate less (P < 0.05) than those injected with saline. In mice treated with nicotine, the mRNA and protein of UCP1 was detected not only in BAT, but also in subcutaneous and retroperitoneal WATs. Immunohistochemically, the BAT of obese mice contained large lipid droplets and appeared rather WAT-like, but changed to typical brown adipocytes after nicotine treatment. The fat pads of nicotine-treated mice contained many multilocular cells that were positive for UCP1.


CONCLUSIONS
Nicotine not only activates UCP1 in BAT, but also induces UCP1 in WAT and decreases food intake, which contributes to the mitigation of obesity.
First Department of Internal Medicine, Kyoto Prefectural University of Medicine, Japan.
T
T
Yoshida
N
N
Sakane
T
T
Umekawa
A
A
Kogure
M
M
Kondo
K
K
Kumamoto
T
T
Kawada
I
I
Nagase
M
M
Saito
D017667:Adipocytes / Q000187:drug effects / Q000378:metabolism; D000273:Adipose Tissue / Q000187:drug effects* / Q000378:metabolism*; D002001:Adipose Tissue, Brown / Q000187:drug effects; D000818:Animals; D015153:Blotting, Western; D002352:Carrier Proteins / Q000187:drug effects* / Q000235:genetics; D005731:Ganglionic Stimulants / Q000494:pharmacology*; D007150:Immunohistochemistry; D007473:Ion Channels; D008565:Membrane Proteins / Q000187:drug effects* / Q000235:genetics; D051379:Mice; D008820:Mice, Obese; D024101:Mitochondrial Proteins; D009538:Nicotine / Q000494:pharmacology*; D018722:Nicotinic Agonists / Q000494:pharmacology*; D009765:Obesity / Q000378:metabolism*; D012313:RNA / Q000032:analysis; D000071256:Uncoupling Protein 1
D002352:Carrier Proteins; D005731:Ganglionic Stimulants; D007473:Ion Channels; D008565:Membrane Proteins; D024101:Mitochondrial Proteins; D018722:Nicotinic Agonists; C000604372:Ucp1 protein, mouse; D000071256:Uncoupling Protein 1; D012313:RNA; D009538:Nicotine