Visfatin is an adipokine, but it is not regulated by thiazolidinediones.
BACKGROUND
Visfatin was recently reported to be expressed in human adipose tissue and to exert insulin-mimicking effects.


OBJECTIVE
The objective of this study was to examine whether visfatin is a true adipokine and is expressed in isolated fat cells. We also examined whether visfatin is regulated by thiazolidinediones and, thus, can contribute to the ability of these agents to improve insulin sensitivity.


METHODS
This was an open-labeled drug therapy trial.


METHODS
This study was performed at a university hospital.


METHODS
Seven newly diagnosed and previously untreated type 2 diabetic patients and six healthy individuals with reduced insulin sensitivity participated in the study.


METHODS
Pioglitazone therapy (30-45 mg/d) was given for 3-4 wk.


METHODS
Serum and adipose tissue mRNA levels of visfatin and adiponectin were the main outcome measures.


RESULTS
Visfatin mRNA is expressed in both adipose tissue and isolated adipocytes. Treatment with thiazolidinediones for 3-4 wk did not alter the gene expression or circulating levels of visfatin in either nondiabetic or the diabetic individuals, whereas adiponectin increased significantly.


CONCLUSIONS
The present study shows that visfatin is a true adipokine, but it is not regulated by TZD and, thus, is unlikely to contribute to the insulin-sensitizing actions of these drugs.
Hammarstedt
Ann
A
Lundberg Laboratory for Diabetes Research, Department of Internal Medicine, Sahlgrenska University Hospital, SE-413 45 Goteborg, Sweden. ann.hammarstedt@medic.gu.se.
Pihlajamäki
Jussi
J
Rotter Sopasakis
Victoria
V
Gogg
Silvia
S
Jansson
Per-Anders
PA
Laakso
Markku
M
Smith
Ulf
U
D000273:Adipose Tissue / Q000187:drug effects / Q000378:metabolism*; D016207:Cytokines / Q000235:genetics*; D003924:Diabetes Mellitus, Type 2 / Q000188:drug therapy*; D005260:Female; D005786:Gene Expression Regulation / Q000187:drug effects; D015309:Glucose Clamp Technique; D006801:Humans; D007004:Hypoglycemic Agents / Q000627:therapeutic use; D008297:Male; D008875:Middle Aged; D054409:Nicotinamide Phosphoribosyltransferase; D012016:Reference Values; D045162:Thiazolidinediones / Q000627:therapeutic use*
D016207:Cytokines; D007004:Hypoglycemic Agents; D045162:Thiazolidinediones; D054409:Nicotinamide Phosphoribosyltransferase; C085455:nicotinamide phosphoribosyltransferase, human