Differential long-term dietary regulation of adipokines, ghrelin, or corticosterone: impact on adiposity.
In the present experiment, we examined in Long-Evans rats the long-term effects of diets that differed in the energy provided by proteins (P) and fats (F) but provided a constant level of energy from carbohydrates (55%) on various hormones regulating feeding and metabolism. Sixty adult rats were fed for 2 months either a high-fat (protein-to-fat, PF 5/40), a control (PF 15/30), low-fat (PF 30/15), or high-protein (PF 40/5) diet ad libitum. Both the PF 30/15 and the PF 40/5 rats ate significantly less than their PF 5/40 and PF 15/30 counterparts throughout the experiment (P<0.001). PF 40/5 rats weighed less than PF 15/30 rats (PL=0.04). PF 40/5 and PF 30/15 rats had smaller epididymal and perirenal adipose tissue depots than PF 5/40 and PF 15/30 rats (P<0.05 or less). Adiponectin (+25-47%) and leptin levels in the PF 5/40 rats were higher than in the three other groups (P<0.0025 or less). Ghrelin concentration in the PF 30/15 group was also higher than in the three other groups (P<0.001 versus PF 5/40; P<0.05 versus PF 15/30 and PF 40/5). Corticosterone level was 2- to 2.5-fold higher in PF 40/5 rats than in the three other groups (P<0.01 or less). Immunoreactive insulin was not different between the four groups. Our current findings thus show that increases in the protein content resulted in a greater degree of leanness, but at sufficiently high levels, also activated the hypothalamo-pituitary axis. Ghrelin appeared to be down-regulated by increases in fat content and no obvious signs of insulin resistance were observed in any of the rats under study.
Beck
Bernard
B
INSERM, U724, Faculté de Médecine, BP 184 F 54505 Vandoeuvre-les-Nancy, France.
Richy
Sébastien
S
D054392:Adipokines / Q000097:blood*; D052242:Adiponectin / Q000097:blood; D050154:Adiposity / Q000502:physiology*; D000818:Animals; D001786:Blood Glucose / Q000032:analysis; D001835:Body Weight; D003345:Corticosterone / Q000097:blood*; D004032:Diet; D004040:Dietary Carbohydrates / Q000008:administration & dosage; D004041:Dietary Fats / Q000008:administration & dosage; D004044:Dietary Proteins / Q000008:administration & dosage; D002149:Energy Intake; D054439:Ghrelin / Q000097:blood*; D006706:Homeostasis / Q000502:physiology; D007328:Insulin / Q000097:blood; D020738:Leptin / Q000097:blood; D008297:Male; D051381:Rats; D020318:Rats, Long-Evans; D014280:Triglycerides / Q000097:blood
D054392:Adipokines; D052242:Adiponectin; D001786:Blood Glucose; D004040:Dietary Carbohydrates; D004041:Dietary Fats; D004044:Dietary Proteins; D054439:Ghrelin; D007328:Insulin; D020738:Leptin; D014280:Triglycerides; D003345:Corticosterone