Lipid deposition in rats centrally infused with leptin in the presence or absence of corticosterone.
The aim of the present study was to assess whether the glucocorticoid corticosterone (Cort) modulates the effects of leptin on food intake and lipid deposition. Rats were subjected to a 6-day intracerebroventricular infusion of leptin and were either sham-adrenalectomized (Sham-ADX) or ADX and supplemented with 0 (C0), 40 (C40), or 80 mg (C80) of Cort. Investigation of potential peripheral sites of interaction of leptin and Cort included liver and plasma triglyceride (TG) content and lipoprotein lipase (LPL) activity in adipose and muscle tissues. The study confirmed the respective anorectic and orexigenic effects of leptin and Cort and revealed that the leptin-induced reduction in food intake was dampened by the high dose of Cort replacement. Such an interaction did not, however, extend to body and adipose tissue weights, which were lowered by leptin infusion independently of the Cort status. Leptin and ADX significantly reduced liver TG content and triglyceridemia, whereas Cort replacement significantly increased these variables. Central infusion of leptin also lowered plasma insulin levels, accompanied by a reduction in LPL activity of storage tissues (inguinal and epididymal white adipose tissue, 2- and 3-fold, respectively). In contrast, leptin infusion increased LPL activity in oxidative tissues (soleus and vastus lateralis muscles, 3- and 4-fold, respectively). Cort replacement prevented the ADX-induced fall in epididymal LPL activity but failed to do so in leptin-infused rats. The study demonstrates that, whereas the anorectic effect of leptin is dampened by high but physiological plasma levels of corticosterone, leptin can produce its effects on body weight, lipid transport and accumulation, and adipose and muscle LPL activity in the absence or presence of an intact hypothalamic-pituitary-adrenal axis.
Arvaniti
K
K
Centre de recherche de l'Hôpital Laval, Centre de recherche sur le métabolisme énergétique, et Département d'anatomie et physiologie, Faculté de médecine, Université Laval, Quebec, Quebec Province, Canada G1K 7P4.
Richard
D
D
Picard
F
F
Deshaies
Y
Y
D000273:Adipose Tissue / Q000187:drug effects / Q000502:physiology; D000315:Adrenalectomy; D000704:Analysis of Variance; D000818:Animals; D001786:Blood Glucose / Q000378:metabolism; D001835:Body Weight / Q000187:drug effects; D002552:Cerebral Ventricles / Q000187:drug effects / Q000502:physiology*; D003345:Corticosterone / Q000097:blood / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D002149:Energy Intake / Q000187:drug effects / Q000502:physiology*; D005163:Factor Analysis, Statistical; D007263:Infusions, Parenteral; D007328:Insulin / Q000097:blood; D020738:Leptin / Q000008:administration & dosage / Q000097:blood / Q000494:pharmacology*; D050356:Lipid Metabolism; D008071:Lipoprotein Lipase / Q000378:metabolism; D008297:Male; D018482:Muscle, Skeletal / Q000187:drug effects / Q000502:physiology; D009929:Organ Size / Q000187:drug effects; D051381:Rats; D017207:Rats, Sprague-Dawley; D014280:Triglycerides / Q000097:blood
D001786:Blood Glucose; D007328:Insulin; D020738:Leptin; D014280:Triglycerides; D008071:Lipoprotein Lipase; D003345:Corticosterone