Circulating leptin levels are modulated by fasting, cold exposure and insulin administration in lean but not Zucker (fa/fa) rats as measured by ELISA.
The development of a sensitive enzyme-linked immunosorbent assay (ELISA) is described for the quantitation of plasma leptin levels in both mice and rats. Approximately 1.5 ng leptin/ml plasma was detected in lean mice but significantly (p < 0.01) less was found in the plasma of ob/ob mice. In lean Zucker rats leptin circulated at approximately 4ng/ml plasma whereas levels were elevated more than 6-fold in fa/fa rats. Circulating leptin levels declined (p < 0.05) in lean rats which were fasted or exposed to 4 degrees C for 24h, but subsequently recovered to normal within 12h of refeeding or warming, respectively. Administration of insulin increased leptin levels in lean rats within 4h (p < 0.01). However, leptin levels were unchanged in fa/fa rats exposed to the same physiological stimuli.
Hardie
L J
LJ
Molecular Physiology Group, Rowett Research Institute, Bucksburn, Aberdeen, Scotland, United Kingdom.
Rayner
D V
DV
Holmes
S
S
Trayhurn
P
P
D000064:Acclimatization; D000818:Animals; D003080:Cold Temperature; D004435:Eating; D004797:Enzyme-Linked Immunosorbent Assay; D005215:Fasting; D007328:Insulin / Q000494:pharmacology*; D020738:Leptin; D008297:Male; D051379:Mice; D008820:Mice, Obese; D009765:Obesity / Q000097:blood*; D011506:Proteins / Q000032:analysis / Q000187:drug effects / Q000378:metabolism*; D051381:Rats; D011924:Rats, Zucker; D013851:Thinness
D007328:Insulin; D020738:Leptin; D011506:Proteins