Direct plasma radioimmunoassay for rat amylin-(1-37)

Concentrations with acquired and genetic obesity

T. R. Pieber, J. Roitelman, Y. Lee, K. L. Luskey, D. T. Stein

Research output: Contribution to journalArticle

70 Citations (Scopus)

Abstract

Amylin (islet-associated polypeptide) is a 37-amino acid peptide that is cosecreted with insulin from the pancreatic β-cell. Accurate measurement of its plasma levels is important for delineating the physiological range over which amylin acts. We describe a reproducible, highly specific, and sensitive radioimmunoassay for direct measurement of plasma amylin-(1-37). We measured changes in portal and systemic plasma amylin and insulin in three groups of anesthetized rats: lean young adult and old adult Wistar rats with acquired obesity, and Wistar fatty [WDF/TaFa (fa/fa)] rats, a model of genetic obesity and insulin resistance derived from the Wistar strain. Changes in response to fasting, feeding, and intravenous stimulation with glucose plus arginine were assessed. We find that the amylin-to-insulin ratio is constant in fasted or fed young and old rats because of proportionate increases in both entities with aging. In genetically obese Wistar rats, amylin and insulin levels are three- to tenfold higher than in lean young or obese old normal controls. Islet stimulation by feeding or intravenous glucose plus arginine resulted in a decreased amylin-to-insulin molar ratio in all groups. When normalized for the degree of islet stimulation, amylin-to-insulin ratios were significantly elevated in genetically obese vs. normal rats, both in the portal and systemic circulation. These results demonstrate that aging-related weight gain in normal rats is associated with moderate and proportional increases in amylin and insulin, whereas genetic obesity is characterized by elevated amylin and an increased amylin-to-insulin ratio. Implications for the pathogenesis of insulin resistance and obesity are discussed.

Original languageEnglish (US)
JournalAmerican Journal of Physiology - Endocrinology and Metabolism
Volume267
Issue number1 30-1
StatePublished - 1994

Fingerprint

Islet Amyloid Polypeptide
Radioimmunoassay
Rats
Obesity
Plasmas
Insulin
Parenteral Nutrition
Arginine
Insulin Resistance
Wistar Rats
Aging of materials
Glucose
Peptides
Genetic Models
Weight Gain
Young Adult
Fasting

Keywords

  • aging
  • animal model
  • cosecretion
  • in vivo
  • insulin resistance
  • portal
  • WDF/TaFa
  • Wistar

ASJC Scopus subject areas

  • Biochemistry
  • Endocrinology
  • Physiology

Cite this

Direct plasma radioimmunoassay for rat amylin-(1-37) : Concentrations with acquired and genetic obesity. / Pieber, T. R.; Roitelman, J.; Lee, Y.; Luskey, K. L.; Stein, D. T.

In: American Journal of Physiology - Endocrinology and Metabolism, Vol. 267, No. 1 30-1, 1994.

Research output: Contribution to journalArticle

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