Investigation of the acute effect of leptin on the inhibition of glycogen catabolism by insulin in rat liver perfused in situ.
Leptin, a cytokine secreted by adipose tissue, has been implicated in the insulin resistance associated with obesity. Here we examined the acute influence of leptin at physiological (10 ng/ml) and supraphysiological (50 ng/ml and 100 ng/ml) concentrations on the inhibition of glycogen catabolism promoted by insulin in rat liver perfusion experiments. Perfusion of the liver with insulin (20 microU/ml) decreased the activation of glucose production (p < 0.05) and glycogenolysis by cAMP (3 microM). However, the infusion of leptin, at concentrations similar to those found in non-obese (10 ng/ml), obese (50 ng/ml), and morbidly obese (100 ng/ml) individuals did not influence the acute inhibitory effect of insulin (20 microU/ml) on glucose production and glycogenolysis stimulated by cAMP (p > 0.05).We conclude that neither physiological nor supraphysiological concentrations of leptin directly influence the inhibition of glycogen catabolism promoted by insulin in rat liver perfused in situ.
Mario
Erica G
EG
Department of Physiological Sciences, State University of Londrina, 86051-990, Londrina, PR, Brazil.
Leonardo
Eledir S
ES
Bassoli
Bruna K
BK
Cassolla
Priscila
P
Borba-Murad
Glaucia R
GR
Bazotte
Roberto B
RB
de Souza
Helenir M
HM
D000818:Animals; D000242:Cyclic AMP / Q000494:pharmacology; D005947:Glucose / Q000096:biosynthesis; D050261:Glycogenolysis / Q000187:drug effects; D007328:Insulin / Q000494:pharmacology*; D020738:Leptin / Q000494:pharmacology*; D008099:Liver / Q000187:drug effects* / Q000378:metabolism; D008112:Liver Glycogen / Q000378:metabolism*; D008297:Male; D010477:Perfusion; D051381:Rats; D017208:Rats, Wistar
D007328:Insulin; D020738:Leptin; D008112:Liver Glycogen; D000242:Cyclic AMP; D005947:Glucose