Leptin secretion is related to glucose-derived lipogenesis in isolated adipocytes.
OBJECTIVE
Leptin secretion in rats is regulated acutely by nutritional state. Insulin plays an important role in this acute nutritional regulation both directly and indirectly through effects on glucose metabolism. The aim of this study was to investigate if the fasting-induced suppression of leptin secretion was reversed by incubation under conditions mimicking nutritional repletion.


METHODS
Leptin secretion and glucose metabolism were measured following incubation with glucose and insulin in adipocytes isolated from fed and fasted rats.


RESULTS
Leptin secretion was stimulated by incubation with glucose and insulin in adipocytes isolated from fed but not from fasted rats as was glucose flux through oxidative and lipogenic pathways. Ob expression and intracellular leptin content were decreased in adipocytes isolated from fasted rats throughout the whole incubation period. Suppression of glucose metabolism with cytochalasin B was accompanied by suppression of leptin secretion. The amount of leptin secretion correlated with the glucose incorporated into lipid under insulin-stimulated conditions.


CONCLUSIONS
It is proposed that glucose incorporation into lipid, at least during insulin-stimulated conditions, reflects the metabolic status of the adipocyte and may be a more important regulator of leptin production and secretion than circulating glucose or insulin levels.
Walker
C G
CG
Human Nutrition Unit, School of Molecular and Microbial Biosciences, G08, University of Sydney, Sydney, NSW, Australia. c.walker@qmul.ac.uk
Bryson
J M
JM
Hancock
D P
DP
Caterson
I D
ID
D017667:Adipocytes / Q000378:metabolism*; D000818:Animals; D002478:Cells, Cultured; D003571:Cytochalasin B / Q000494:pharmacology; D005215:Fasting; D015870:Gene Expression / Q000235:genetics; D005947:Glucose / Q000378:metabolism*; D007328:Insulin / Q000378:metabolism; D019344:Lactic Acid / Q000096:biosynthesis; D020738:Leptin / Q000096:biosynthesis / Q000235:genetics / Q000378:metabolism*; D050155:Lipogenesis / Q000502:physiology*; D008297:Male; D051381:Rats; D017208:Rats, Wistar
D007328:Insulin; D020738:Leptin; D019344:Lactic Acid; D003571:Cytochalasin B; D005947:Glucose