Interactions of amylinergic and melanocortinergic systems in the control of food intake and body weight in rodents.

Abstract

AIMS:

Amylinergic and melanocortinergic systems have each been implicated in energy balance regulation. We examined the interactive effects of both systems using gene knockout and pharmacological approaches.

METHODS:

Acute food consumption was measured in overnight fasted male wild-type (WT) and melanocortin-4 receptor (MC-4R) deficient rats and in male and female WT and amylin knockout mice (AmyKO). Changes in food intake, body weight and composition in male WT and MC-4R deficient rats and in male diet-induced obese (DIO) rats. Pharmacological treatments included either rat amylin, murine leptin and/or the MC-4R agonist, Ac-R[CEH-dF-RWC]-amide.

RESULTS:

Amylin (10 µg/kg, IP) decreased food intake in WT but not in MC-4R deficient rats (30 and 60 min post-injection). Ac-R[CEH-dF-RWC]-amide (100 µg/kg, IP) suppressed food intake similarly in male WT and AmyKO, but was ineffective in female AmyKO. Amylin (50 µg/kg/day for 28 days) and leptin (125 µg/kg/day) synergistically reduced food intake and body weight in WT and MC-4R deficient rats to a similar extent. Amylin (100 µg/kg) combined with Ac-R[CEH-dF-RWC]-amide (100 µg/kg, IP) decreased acute food intake over 3 h to a greater extent than either agent alone in fasted mice. In DIO rats, additive anorexigenic, weight- and fat-lowering effects were observed over 12 days with the combination of rat amylin (50 µg/kg/day) and Ac-R[CEH-dF-RWC]-amide (2.3 mg/kg, SC injected daily).

CONCLUSIONS:

Although amylin's acute anorexigenic effects are somewhat blunted in MC-4R deficiency and those of MC-4R agonism in amylin deficiency, these effects are surmountable with pharmacological administration lending therapeutic potential to combined amylin/melanocortin agonism for obesity.

• Authors: J D Roth, L D'Souza, P S Griffin, J Athanacio, J L Trevaskis, R Nazarbaghi, C Jodka, J Athanacio, J Hoyt, B Forood, D G Parkes
• Journal: Diabetes, obesity & metabolism (Diabetes Obes Metab) Vol. 14 Issue 7 Pg. 608-15 (Jul 2012) ISSN: 1463-1326 [Electronic] England
• PMID: 22276636 (Publication Type: Journal Article)
• Copyright: © 2012 Blackwell Publishing Ltd.

Chemical References

• Anti-Obesity Agents
• Islet Amyloid Polypeptide
• Receptor, Melanocortin, Type 4

Topics

• Animals
• Anti-Obesity Agents (pharmacology)
• Body Weight
• Disease Models, Animal
• Drug Interactions
• Eating
• Energy Metabolism
• Female
• Gene Knockout Techniques
• Islet Amyloid Polypeptide (administration & dosage, deficiency, pharmacology)
• Male
• Mice
• Obesity (drug therapy)
• Rats
• Rats, Sprague-Dawley
• Receptor, Melanocortin, Type 4 (agonists, deficiency)