Horm Metab Res 2004; 36(9): 607-613
DOI: 10.1055/s-2004-825905
Original Basic
© Georg Thieme Verlag KG Stuttgart · New York

Effects of Growth Hormone (GH) on mRNA Levels of Uncoupling Proteins 1, 2, and 3 in Brown and White Adipose Tissues and Skeletal Muscle in Obese Mice

C.  Hioki1, 3 , T.  Yoshida1 , A.  Kogure1 , Y.  Takakura1 , T.  Umekawa1 , K.  Yoshioka1 , A.  Shimatsu3 , T.  Yoshikawa2
  • 1Department of Endocrinology and Metabolism, Graduate School of Medical Science, Kyoto Prefectural University of Medicine, Japan
  • 2Department of Inflammation and Immunology, Graduate School of Medical Science, Kyoto Prefectural University of Medicine, Japan
  • 3Clinical Research Institute for Endocrine and Metabolic Diseases, National Hospital Organization, Kyoto Medical Center, Japan
Further Information

Publication History

Received 28 October 2003

Accepted after revision 20 April 2004

Publication Date:
05 October 2004 (online)

Abstract

We have investigated whether GH treatment influences the expression of UCP1, 2 and 3 mRNA in a KK-Ay obese mouse model. KK-Ay mice (n = 10) and C57Bl/6J control mice (n = 10) were injected subcutaneously with human GH (1.0 mg/kg/day and 3.5 mg/kg/day) for 10 days, and compared with mice injected with physical saline. The KK-Ay obese mice weighed significantly less (p < 0.01 : 1.0 mg/kg/day, p < 0.05 : 3.5 mg/kg/day) and had smaller inguinal subcutaneous and perimetric white adipose tissue (WAT) pads (p < 0.05 : 3.5 mg/kg/day), but increased skeletal muscle weight (p < 0.05). The brown adipose tissue (BAT) weight did not change significantly. Not only plasma free fatty acid and glucose levels but also plasma insulin levels decreased. The reduced HOMA-IR (homeostasis model assessment-insulin resistance) values suggested that insulin resistance was improved by GH treatment. UCP1 mRNA levels increased after the 3.5 mg GH treatment by 2.8-fold (p < 0.01 vs. saline controls) and 2.0-fold (p < 0.05 vs. 1 mg GH treatment) in BAT, and by 6.0-fold in subcutaneous WAT (p < 0.05 vs. controls). UCP2 mRNA levels increased 2.2-fold (p < 0.05 vs. control) and 2.1-fold (p < 0.05 vs. 1 mg GH treatment) in BAT, and 2.0-fold (p < 0.05 vs. controls) in skeletal muscle. One mg GH administration also stimulated UCP1 mRNA expression by 2.5-fold (p < 0.05 vs. controls) and UCP3 mRNA expression by 2.8-fold (p < 0.05 vs. controls) in the muscle. On the other hand, lean mice showed no significant difference in body composition or plasma parameters. UCP1, 2 and 3 mRNA expression in lean mice did not show any significant change after treatment with GH. We conclude that GH treatment increased mRNA levels for not only UCP1, but also UCP 2 and 3 in BAT, WAT and muscle in a KK-Ay obese mouse model. These findings suggest that GH-induced thermogenesis may contribute to the reduction in WAT and energy expenditure.

References

C. Hioki

Department of Endocrinology and Metabolism, Graduate School of Medical Science, Kyoto Prefectural University of Medicine

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Email: chioki@koto.kpu-m.ac.jp