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Int J Obes (Lond). 2009 May;33(5):541-52. doi: 10.1038/ijo.2009.40. Epub 2009 Feb 24.

Acylated and desacyl ghrelin stimulate lipid accumulation in human visceral adipocytes.

Author information

1
Metabolic Research Laboratory, Clínica Universitaria de Navarra, University of Navarra, Pamplona, Spain.

Abstract

OBJECTIVES:

The orexigenic hormone ghrelin circulates mainly in two forms, acylated and desacyl ghrelin. We evaluated the impact of obesity and obesity-associated type 2 diabetes (T2D) on ghrelin forms and the potential role of acylated and desacyl ghrelin in the control of adipogenesis in humans.

METHODS:

Plasma concentrations of the different ghrelin forms were measured in 80 subjects. The expression of the ghrelin receptor (growth hormone secretagogue receptor, GHS-R) was analyzed in omental adipose tissue using western blot and immunohistochemistry, and the effect of acylated ghrelin and desacyl ghrelin (0.1-1000 pmol l(-1)) on adipogenesis was determined in vitro in omental adipocytes.

RESULTS:

Circulating concentrations of acylated ghrelin were increased, whereas desacyl ghrelin levels were decreased, in obesity and obesity-associated T2D. Body mass index, waist circumference, insulin and HOMA (homeostasis model assessment) index were positively correlated with acylated ghrelin levels. Obese individuals showed a lower protein expression of GHS-R in omental adipose tissue. In differentiating omental adipocytes, incubation with both acylated and desacyl ghrelin significantly increased PPARgamma (peroxisome proliferator-activated receptor gamma) and SREBP1 (sterol-regulatory element binding protein-1) mRNA levels, as well as several fat storage-related proteins, including acetyl-CoA carboxylase, fatty acid synthase, lipoprotein lipase and perilipin. Consequently, both the ghrelin forms stimulated intracytoplasmatic lipid accumulation.

CONCLUSIONS:

Both acylated and desacyl ghrelin stimulate lipid accumulation in human visceral adipocytes. Given the lipogenic effect of acylated ghrelin on visceral adipocytes, the herein-reported elevation of its circulating concentrations in obese individuals may play a role in excessive fat accumulation in obesity.

PMID:
19238155
DOI:
10.1038/ijo.2009.40
[Indexed for MEDLINE]

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