Leptin does not fully account for the satiety activity of adipose tissue-conditioned medium.
To determine whether leptin alone accounts for the satiety activity secreted by native adipose tissue, we prepared culture media conditioned by microdissected adipose tissue from overfed Long-Evans rats, fa/fa rats, or db/db mice (media A, B, and C, respectively). Medium A significantly suppressed food intake following intracerebroventricular delivery to Long-Evans rats (2-h chow intake = 68 +/- 5% of baseline, P < 0.001). Media B and C significantly suppressed food intake following intraperitoneal delivery to ob/ob mice (24-h chow intake = 56 +/- 7% of baseline for medium B, P = 0. 001; 4-day chow intake = 78 +/- 3% of baseline for medium C, P = 0. 004). Using a leptin receptor-based bioassay, we determined that the leptin concentration of medium C was 392 +/- 18 ng/ml. This concentration was 20-fold lower than the concentration of recombinant murine leptin required to produce a similar degree of feeding suppression following 5 days of administration to ob/ob mice. Neither medium conditioned by adipose tissue from ob/ob mice nor medium conditioned by adipose tissue from fa/fa rats and subsequently immunodepleted of leptin had significant satiety activity. We conclude that leptin is necessary but not sufficient to account for the satiety activity of native adipose tissue, perhaps due to the production by adipocytes of a cofactor that augments the ability of leptin to suppress feeding.
Department of Medicine, University of Washington School of Medicine, Seattle, Washington 98195, USA.
D S
DS
Weigle
A M
AM
Hutson
J M
JM
Kramer
M G
MG
Fallon
J M
JM
Lehner
S
S
Lok
J L
JL
Kuijper
D000273:Adipose Tissue / Q000166:cytology / Q000502:physiology*; D000818:Animals; D017077:Culture Media, Conditioned / Q000494:pharmacology*; D003924:Diabetes Mellitus, Type 2 / Q000235:genetics / Q000503:physiopathology; D005215:Fasting; D020738:Leptin; D008297:Male; D051379:Mice; D008817:Mice, Mutant Strains; D008820:Mice, Obese; D017551:Microdialysis; D009765:Obesity / Q000235:genetics / Q000503:physiopathology; D011506:Proteins / Q000494:pharmacology* / Q000502:physiology; D051381:Rats; D020318:Rats, Long-Evans; D011924:Rats, Zucker; D011994:Recombinant Proteins / Q000494:pharmacology; D012528:Satiety Response / Q000187:drug effects / Q000502:physiology*; D013045:Species Specificity
D017077:Culture Media, Conditioned; D020738:Leptin; D011506:Proteins; D011994:Recombinant Proteins