title: Serum leptin response to endogenous hyperinsulinemia in aging rats.
abstract: To determine if aging is associated with altered serum leptin response to diet-induced changes in endogenous hyperinsulinemia, male Fisher 344 (F344) rats at different age groups were studied while on regular rat chow and following 10 days of experimental diets consisting of 60% of the weight as fructose or glucose. The serum leptin concentration (ng/ml) gradually increased from basal levels of 2.5+/-0.1 at age of 4 months to 3.7+/-0.1, 6.9+/-0.9, 9. 4+/-0.3 and 8.9+/-1.1 at 6, 12, 18 and 24 months of age, respectively (P<0.001). Hyperinsulinemia associated with 60% fructose diet was associated with increased serum leptin levels in 4, 12, and 24 month old rats to 5.1+/-0.8, 6.7+/-1.2, and 8.6+/-1.1, respectively (P<0.001). Feeding 60% glucose diet also was associated with increased serum leptin levels in 4, 12 and 24 month old rats to 7.6+/-0.6, 7.2+/-0.7, and 9.1+/-1.1, respectively (P<0.001). Restricting dietary intake to 60% of the calories consumed by control rats for 10 days resulted in a decrease in serum leptin to 1.0+/-0.02 in 4 month old rats and 2.5+/-0.4 in 24 month old rats (P<0.01). It is concluded that aging in F344 rats is associated with increased serum leptin concentrations. However, diet-related hyperinsulinemic effect on leptin is blunted in aging rats although leptin response to caloric restriction is maintained. The inability of aging rats to mount hyperleptinemic response to dietary changes may contribute to the age-related increase in adiposity.
authors.affiliation: Department of Internal Medicine, Division of Endocrinology, Diabetes and Metabolism, Health Sciences Center, Saint Louis University School of Medicine, 1402 South Grand Boulevard, St Louis, MO 63104, USA.
authors.forename: A D
authors.initials: AD
authors.lastname: Mooradian
authors.forename: J M
authors.initials: JM
authors.lastname: Chehade
mesh_terms: D000375:Aging / Q000097:blood*; D000818:Animals; D019422:Dietary Sucrose / Q000008:administration & dosage / Q000494:pharmacology; D002149:Energy Intake; D005632:Fructose / Q000008:administration & dosage / Q000494:pharmacology; D005947:Glucose / Q000008:administration & dosage / Q000494:pharmacology; D006946:Hyperinsulinism / Q000097:blood*; D020738:Leptin / Q000097:blood*; D008297:Male; D009994:Osmolar Concentration; D051381:Rats; D011916:Rats, Inbred F344
chemical_list: D019422:Dietary Sucrose; D020738:Leptin; D005632:Fructose; D005947:Glucose