Loss of body fat in lean parabiotic partners of ob/ob mice.
The objective of this experiment was to confirm whether changes in serum leptin and leptin expression were consistent with it being the "lipostatic" factor implicated by earlier parabiosis studies. Lean (+/?) and obese (ob/ob) female C57B1/6J-ob mice were parabiosed (lean-ob/ob) at 7 wk of age. Controls were ob/ob-ob/ob and lean-lean pairs, and single lean and ob/ob mice. Pairs were maintained for 50 days. In ob/ob members of lean-ob/ob pairs serum insulin was normalized, food intake was suppressed, and body fat was reduced by 14%. Lean partners of ob/ob mice had a reduced rectal temperature and experienced a 37% reduction in body fat. Despite loss of fat, serum leptin and adipose leptin mRNA expression were unchanged in lean partners of ob/ob mice. These results suggest that, in lean-ob/ob parabiotic pairs, the ob/ob mouse responds to leptin originating in the lean parabiont, whereas the lean partner responds to a circulating signal, originating in the ob/ob mouse, that maintains leptin expression at inappropriate levels for the degree of adiposity of the lean animal.
Harris
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Pennington Biomedical Research Center, Baton Rouge, Louisiana 70808, USA.
D000273:Adipose Tissue / Q000378:metabolism / Q000473:pathology*; D000818:Animals; D001831:Body Temperature; D001835:Body Weight; D004435:Eating; D005260:Female; D007328:Insulin / Q000097:blood; D020738:Leptin; D051379:Mice; D008810:Mice, Inbred C57BL; D009765:Obesity / Q000378:metabolism / Q000473:pathology*; D009929:Organ Size; D010227:Parabiosis; D011506:Proteins / Q000235:genetics / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D012007:Rectum; D012016:Reference Values
D007328:Insulin; D020738:Leptin; D011506:Proteins; D012333:RNA, Messenger