Troglitazone lowers islet fat and restores beta cell function of Zucker diabetic fatty rats

Michio Shimabukuro, Yang Ting Zhou, Young Lee, Roger H. Unger

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Abstract

The thiazolidinedione compound troglitazone, which is used to treat non- insulin-dependent diabetes mellitus (NIDDM) in man, is also effective in the adipogenic NIDDM of Zucker diabetic fatty (ZDF) rats. To test the 'lipotoxicity hypothesis,' which attributes the beta cell dysfunction of adipogenic NIDDM to an excessive accumulation of fat in the pancreatic islets, we sought to determine if troglitazone-mediated amelioration of beta cell function in islets of ZDF rats might be associated with a reduction in their elevated triglyceride (TG) content. Troglitazone (10 μM) in the culture medium reduced the TG content of ZDF rats by 52%; this was reflected by decreased esterification and increased oxidation of [3H]palmitate. Glycerol-3-phosphate acyl-transferase mRNA fell by 57% and acyl-CoA synthetase mRNA by 67% (brain isoform) and 38% (liver isoform), all consistent with the effects of troglitazone on TG metabolism. The 52% decrease in islet TG was accompanied by >30- and 2-fold improvements in glucose- and arginine-stimulated insulin secretion, respectively. We conclude that troglitazone exerts direct lipopenic activity in normal islets and in islets of obese prediabetic ZDF rats; in the latter, this correlated with improvement in beta cell function. The results are consistent with the lipotoxicity hypothesis for adipogenic diabetes.

Original languageEnglish (US)
Pages (from-to)3547-3550
Number of pages4
JournalJournal of Biological Chemistry
Volume273
Issue number6
DOIs
StatePublished - Feb 6 1998

Fingerprint

troglitazone
Rats
Medical problems
Fats
Triglycerides
Insulin
Type 2 Diabetes Mellitus
Protein Isoforms
Coenzyme A Ligases
Messenger RNA
Esterification
Palmitates
Transferases
Islets of Langerhans
Metabolism
Liver
Culture Media
Arginine
Brain
Glucose

ASJC Scopus subject areas

  • Biochemistry

Cite this

Troglitazone lowers islet fat and restores beta cell function of Zucker diabetic fatty rats. / Shimabukuro, Michio; Zhou, Yang Ting; Lee, Young; Unger, Roger H.

In: Journal of Biological Chemistry, Vol. 273, No. 6, 06.02.1998, p. 3547-3550.

Research output: Contribution to journalArticle

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