Contribution of glucocorticoid-mineralocorticoid receptor pathway on the obesity-related adipocyte dysfunction.
OBJECTIVE
Mineralocorticoid receptor (MR) blockade ameliorated insulin resistance with improvements in adipocytokine dysregulation, inflammation, and excess of reactive oxygen species (ROS) in obese adipose tissue and adipocytes, but its mechanism has not been clarified. The 11β-hydroxysteroid dehydrogenase type 1 (11β-HSD1), producing active glucocorticoids, is highly expressed in adipocytes and glucocorticoids bind to MR with higher affinity than to glucocorticoid receptor (GR). We investigated whether glucocorticoids effect on adipocytokines and ROS through MR in adipocytes. In addition, fat distributions of MR and GR were investigated in human subjects.


RESULTS
Corticoid receptors and their target genes were examined in adipose tissue of obese db/db mice. 3T3-L1 adipocytes were treated with glucocorticoids, H(2)O(2), MR antagonist eplerenone (EP), GR antagonist RU486 (RU), MR-siRNA, and/or N-acetylcysteine. Human adipose tissues were obtained from seven patients who underwent abdominal surgery. The mRNA levels of MR and its target gene were higher in db/db mice than in control db/m+mice. In 3T3-L1 adipocytes, glucocorticoids, similar to H(2)O(2), caused the dysregulation of mRNA levels of various genes related to adipocytokines and the increase of intracellular ROS. Such changes were rectified by MR blockade, not by GR antagonist. In human fat, MR mRNA level was increased in parallel with the increase of body mass index (BMI) and its increase was more significant in visceral fat, while there were no apparent correlations of GR mRNA level to BMI or fat distribution.


CONCLUSIONS
Glucocorticoid-MR pathway may contribute to the obesity-related adipocytokine dysregulation and adipose ROS.
Department of Metabolic Medicine, Graduate School of Medicine, Osaka University, 2-2-B5 Yamada-oka, Suita, Osaka 565-0871, Japan. hirata@endmet.med.osaka-u.ac.jp
Ayumu
A
Hirata
Norikazu
N
Maeda
Hideaki
H
Nakatsuji
Aki
A
Hiuge-Shimizu
Takuya
T
Okada
Tohru
T
Funahashi
Iichiro
I
Shimomura
D043205:11-beta-Hydroxysteroid Dehydrogenase Type 1 / Q000378:metabolism; D041721:3T3-L1 Cells; D017667:Adipocytes / Q000378:metabolism*; D054392:Adipokines / Q000378:metabolism*; D000818:Animals; D015992:Body Mass Index; D000077545:Eplerenone; D005938:Glucocorticoids / Q000096:biosynthesis / Q000378:metabolism*; D006801:Humans; D008297:Male; D053858:Metabolic Networks and Pathways; D051379:Mice; D008817:Mice, Mutant Strains; D015735:Mifepristone / Q000494:pharmacology; D000451:Mineralocorticoid Receptor Antagonists; D009765:Obesity / Q000378:metabolism*; D034741:RNA, Small Interfering / Q000235:genetics; D011965:Receptors, Glucocorticoid / Q000037:antagonists & inhibitors / Q000378:metabolism; D018161:Receptors, Mineralocorticoid / Q000378:metabolism*; D013148:Spironolactone / Q000031:analogs & derivatives / Q000494:pharmacology
D054392:Adipokines; D005938:Glucocorticoids; D000451:Mineralocorticoid Receptor Antagonists; D034741:RNA, Small Interfering; D011965:Receptors, Glucocorticoid; D018161:Receptors, Mineralocorticoid; D013148:Spironolactone; D015735:Mifepristone; D000077545:Eplerenone; D043205:11-beta-Hydroxysteroid Dehydrogenase Type 1