Evidence that amylin stimulates lipolysis in vivo: A possible mediator of induced insulin resistance

Ji Ming Ye, Megan Lim-Fraser, Gregory J. Cooney, Garth J S Cooper, Miguel A. Iglesias, David G. Watson, Bernard Choong, Edward W. Kraegen

Research output: Contribution to journalArticlepeer-review

Abstract

The present study investigated the role of amylin in lipid metabolism and its possible implications for insulin resistance. In 5- to 7-h-fasted conscious rats, infusion of rat amylin (5 nmol/h for 4 h) elevated plasma glucose, lactate, and insulin (P <0.05 vs. control, repeated-measures ANOVA) with peak values occurring within 60 min. Despite the insulin rise, plasma nonesterified fatty acids (NEFA) and glycerol were also elevated (P <0.001 vs. control), and these elevations (80% above basal) were sustained over the 4-h infusion period. Although unaltered in plasma, triglyceride content in liver was increased by 28% (P <0.001) with a similar tendency in muscle (18%, P = 0.1). Infusion of the rat amylin antagonist amylin-(8-37) (125 nmol/h) induced opposite basal plasma changes to amylin, i.e., lowered plasma NEFA, glycerol, glucose, and insulin levels (all P <0.05 vs. control); additionally, amylin-(8-37) blocked amylin-induced elevations of these parameters (P <0.01). Treatment with acipimox (10 mg/kg), an anti-lipolytic agent, before or after amylin infusion blocked amylin's effects on plasma NEFA, glycerol, and insulin but not on glucose and lactate. We conclude that amylin could exert a lipolytic-like action in vivo that is blocked by and is opposite to effects of its antagonist amylin-(8-37). Further studies are warranted to examine the physiological implications of lipid mobilization for amylin-induced insulin resistance.
Original languageEnglish
Pages (from-to)E562-E569
JournalAJP: Endocrinology and Metabolism
Volume280
Issue number4
Publication statusPublished - Apr 2001

Keywords

  • Acipimox
  • Amylin antagonist
  • Fatty acids
  • Glucose

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