Overexpression of GLUT4 in mice causes up-regulation of UCP3 mRNA in skeletal muscle

Mitochondrial uncoupling protein 3 (UCP3) is expressed in skeletal muscles. We have hypothesized that increased glucose flux in skeletal muscles may lead to increased UCP3 expression. Male transgenic mice harboring insulin-responsive glucose transporter (GLUT4) minigenes with differing lengths of 5'-flanking sequence (-3237, -2000, -1000 and -442 bp) express different levels of GLUT4 protein in various skeletal muscles. Expression of the GLUT4 transgenes caused an increase in UCP3 mRNA that paralleled the increase of GLUT4 protein in gastrocnemius muscle. The effects of increased intracellular GLUT4 level on the expression of UCP1, UCP2 and UCP3 were compared in several tissues of male 4 month-old mice harboring the -1000 GLUT4 minigene transgene. In the -1000 GLUT4 transgenic mice, expression of GLUT4 mRNA and protein in skeletal muscles, brown adipose tissue (BAT), and white adipose tissue (WAT) was increased by 1.4 to 4.0-fold. Compared with non-transgenic littermates, the -1000 GLUT4 mice exhibited about 4- and 1.8-fold increases of UCP3 mRNA in skeletal muscle and WAT, respectively, and a 38% decrease of UCP1 mRNA in BAT. The transgenic mice had a 16% increase in oxygen consumption and a 14% decrease in blood glucose and a 68% increase in blood lactate, but no change in FFA or beta-OHB levels. T3 and leptin concentrations were decreased in transgenic mice. Expression of UCP1 in BAT of the -442 GLUT4 mice, which did not overexpress GLUT4 in this tissue, was not altered. These findings indicate that overexpression of GLUT4 up-regulates UCP3 expression in skeletal muscle and down-regulates UCP1 expression in BAT, possibly by increasing the rate of glucose uptake into these tissues.     

Absence of UCP3 in brown adipose tissue does not impair nonshivering thermogenesis

We report on a novel Djungarian hamster mutant lineage that exhibits a loss of uncoupling protein (UCP) 3 mRNA and protein in brown adipose tissue (BAT), whereas UCP3 expression in skeletal muscle is only mildly diminished. In response to 2 d of cold exposure, UCP3 mRNA was 4.5-fold elevated in BAT of wild-type hamsters but remained undetectable in mutant hamsters. Notably, in BAT of warm- and cold-exposed mutant hamsters, UCP1 and UCP2 mRNA levels were increased. The tissue specificity of UCP3 deficiency suggests that the underlying unknown mutation impairs a factor controlling UCP3 gene expression selectively in brown adipocytes. In wild-type but not mutant primary brown adipocytes, UCP3 gene expression was stimulated by treatment with peroxisome proliferator activated receptor (PPAR) ligands. This implies that the underlying mutation causing UCP3 deficiency is expressed within brown adipocytes and disrupts PPAR-dependent transactivation of the UCP3 gene. On the functional level, we found no direct phenotypic consequences of altered UCP expression in BAT. The absence of UCP3 in BAT of cold-acclimated mutant hamsters affected neither maximal nonshivering thermogenesis elicited by noradrenaline nor the uncoupled respiration of isolated mitochondria in the presence of oligomycin and in response to palmitate.     

Dietary vitamin A supplementation in rats: suppression of leptin and induction of UCP1 mRNA

All-trans-retinoic acid (RA), an active metabolite of vitamin A, induces the gene expression of uncoupling protein 1 (UCP1) in brown adipose tissue (BAT) and suppresses leptin gene expression in white adipose tissue (WAT) when given as an acute dose. These contrasting effects of RA leave in doubt the overall effect of chronic RA or vitamin A supplementation on energy homeostasis. To investigate the effects of dietary vitamin A supplementation on leptin and UCP1 gene expression, rats were fed either a normal diet (2.6 retinol/kg diet) or a vitamin A-supplemented diet (129 mg retinol/kg diet) for 8 weeks, and adiposity, serum leptin levels, leptin mRNA levels in perirenal WAT, UCP1 and UCP2 mRNA levels in BAT, and beta3-adrenergic receptor mRNA levels in BAT and WAT were examined. Rats on both diets gained a similar amount of weight, but there was a small 9% decrease in the adiposity index in the vitamin A-supplemented rats. Dietary vitamin A supplementation increased UCP1 gene expression in BAT by 31%, but suppressed leptin gene expression by 44% and serum leptin levels by 65%. UCP2 and beta3-adrenergic receptor gene expression in BAT and perirenal WAT were unchanged by the vitamin A diet. These data suggest that dietary vitamin A has a role in regulating energy homeostasis by enhancing UCP1 gene expression and decreasing serum leptin levels.     

Regulation of UCP1 and UCP3 in arctic ground squirrels and relation with mitochondrial proton leak.

Uncoupling protein (UCP) 1 (UCP1) catalyzes a proton leak in brown adipose tissue (BAT) mitochondria that results in nonshivering thermogenesis (NST), but the extent to which UCP homologs mediate NST in other tissues is controversial. To clarify the role of UCP3 in mediating NST in a hibernating species, we measured Ucp3 expression in skeletal muscle of arctic ground squirrels in one of three activity states (not hibernating, not hibernating and fasted for 48 h, or hibernating) and housed at 5 degrees C or -10 degrees C. We then compared Ucp3 mRNA levels in skeletal muscle with Ucp1 mRNA and UCP1 protein levels in BAT in the same animals. Ucp1 mRNA and UCP1 protein levels were increased on cold exposure and decreased with fasting, with the highest UCP1 levels in thermogenic hibernators. In contrast, Ucp3 mRNA levels were not affected by temperature but were increased 10-fold during fasting and >3-fold during hibernation. UCP3 protein levels were increased nearly fivefold in skeletal muscle mitochondria isolated from fasted squirrels compared with nonhibernators, but proton leak kinetics in the presence of BSA were unchanged. Proton leak in BAT mitochondria also did not differ between fed and fasted animals but did show classical inhibition by the purine nucleotide GDP. Levels of nonesterified fatty acids were highest during hibernation, and tissue temperatures during hibernation were related to Ucp1, but not Ucp3, expression. Taken together, these results do not support a role for UCP3 as a physiologically relevant mediator of NST in muscle.     

禁食及胰岛素水平对大鼠解偶联蛋白-1、2、3基因表达的影响

 为探讨禁食和胰岛素对解偶联蛋白 - 1、2、3基因 (UCP1 ,2 ,3)表达的影响 ,应用 RT- PCR方法观察了在不同禁食时间和应用胰岛素条件下大鼠白色脂肪组织、棕色脂肪组织和骨骼肌中 UCP1 ,2 ,3m RNA水平的变化 .UCP1基因只在大鼠棕色脂肪组织中表达 .UCP2 ,3基因在三种组织中均有表达 ,在白色脂肪组织中以 UCP2表达为主 ;在骨骼肌中以 UCP3表达为主 .过夜禁食使棕色脂肪组织 UCP1 ,3m RNA水平明显下降 (P<0 .0 1 ) ;UCP2 m RNA水平在三种组织中均呈上升反应 ,以白色脂肪组织中表现最为明显 (P<0 .0 5) ;而对白色脂肪组织和骨骼肌中 UCP3基因表达无明显影响 .禁食时间延长至 48h,除棕色脂肪组织中 UCP2 ,3基因有明显下降外 ,各组织中UCPs基因表达基本调节至正常或高于对照组水平 .胰岛素对 UCPs基因表达水平有一定的上调作用 ,这一作用对棕色脂肪组织 UCPs各基因及骨骼肌中 UCP3基因表现得尤为明显 (P<0 .0 5) .大鼠 UCPs基因表达有一定的组织特异性 ;禁食时间对三种组织中 UCPs各成员基因表达的影响有时相上的区别 ;胰岛素可以调 UCPs各成员基因的表达 .结果反映了 UCPs各成员在能量代谢调节上的不同作用 ,这为理解膳食 -产热与体重调节的关系 ,及其能量代谢平衡与疾病关系提供了实验依据     

侧脑室注射CRH 对急性冷暴露长爪沙鼠BAT 产热的影响及产热调节机理

长爪沙鼠侧脑室注射促肾上腺皮质激素释放激素(CRH) 8μg 或CRH受体阻断剂2.5μg 后, 4 ±1 ℃暴露3 h ,对照组注射等体积生理盐水并置于24 ±2 ℃或4 ±1 ℃下。与常温对照组相比, 低温对照组褐色脂肪组织(BAT) 重量下降, BAT中解偶联蛋白(UCP1) mRNA 上调; 下丘脑促甲状腺激素释放激素(TRH) 含量降低, 血清T₃ 、T₄ 、T₃/T₄水平及BAT中T₄5′脱碘酶活性均增加, 血清去甲肾上腺素(NE) 含量上升。与低温对照组相比, 侧脑室注射CRH后再冷暴露, BAT重量、蛋白总含量和UCP1 mRNA 含量趋于减少; 血清NE 含量上升, BAT 中T₄ 5′脱碘酶活性增加, 但下丘脑TRH 含量、血清T₃ 、T₄ 及T₃/T₄ 水平均降低。侧脑室注射215μg 的CRH 受体阻断剂α- helical CRH 9 - 41 , 对冷暴露长爪沙鼠甲状腺轴的分泌、BAT重量、血清中NE 水平及UCP1 mRNA 含量没有明显影响。结果表明, 急性冷暴露激活了长爪沙鼠下丘脑- 垂体- 甲状腺(HPT) 轴和交感神经系统, 刺激BAT产热和UCP1 合成; 而CRH作用于中枢, 可能一方面抑制HPT轴的分泌, 进而抑制UCP1 的基因表达, 另一方面又刺激交感神经,增加产热。     

Leptin selectively reduces white adipose tissue in mice via a UCP1-dependent mechanism in brown adipose tissue

We tested the hypothesis that leptin, in addition to reducing body fat by restraining food intake, reduces body fat through a peripheral mechanism requiring uncoupling protein 1 (UCP1). Leptin was administered to wild-type (WT) mice and mice with a targeted disruption of the UCP1 gene (UCP1 deficient), while vehicle-injected control animals of each genotype were pair-fed to each leptin-treated group. Leptin reduced the size of white adipose tissue (WAT) depots in WT mice but not in UCP1-deficient animals. This was accompanied by a threefold increase in the amount of UCP1 protein and mRNA in the brown adipose tissue (BAT) of WT mice. Leptin also increased UCP2 mRNA in WAT of both WT and UCP1-deficient mice but increased UCP2 and UCP3 mRNA only in BAT from UCP1-deficient mice. These results indicate that leptin reduces WAT through a peripheral mechanism requiring the presence of UCP1, with little or no involvement of UCP2 or UCP3.     

Intrauterine food restriction alters the expression of uncoupling proteins in brown adipose tissue of rat newborns

A previous study from our laboratory showed that maternal food restriction (MFR) delays thermoregulation in newborn rats. In neonates brown adipose tissue (BAT) is essential for thermogenesis due to the presence of uncoupling proteins (UCPs). The aim of this study was to evaluate the influence of MFR on the UCPs mRNA and protein expression in BAT and skeletal muscle (SM) of the newborn rat. Female Wistar EPM-1 control rats (CON) received chow ad libitum during pregnancy, whereas food-restricted dams (RES) received 50% of the amount ingested by CON. Fifteen hours after birth, the litters were weighed and sacrificed. Blood was collected for hormonal analysis. BAT and SM were used for determination of UCPs mRNA and protein expression, and Ca²⁺-ATPase sarcoplasmic reticulum (SERCA1). RES pups showed a significant reduction in body weight and fat content at birth. MFR caused a significant increase in the expression of UCP1 and UCP2 in BAT, without changes in UCP3 and SERCA1 expression in BAT and SM. No differences between groups were found for leptin, T4 and glucose levels. RES pups showed increased insulin and decreased T3 levels. The delay in development of thermoregulation previously described in RES animals appears not to result from impairment in thermogenesis, but from an increase in heat loss, since MFR caused low birth weight in pups, leading to greater surface/volume ratio. The higher expression of UCP1 and UCP2 in BAT suggests a compensatory mechanism to increased thermogenesis.     

Immortal brown adipocytes from p53-knockout mice: differentiation and expression of uncoupling proteins

Brown adipose tissue (BAT) is the specific site for metabolic heat production in mammals. To establish a novel immortal brown adipocyte cell line, the stromal-vascular fraction containing preadipocytes was obtained from interscapular BAT of mice deficient of a tumor-suppressor gene p53. The p53-deficient cells, tentatively named as HB2 cells, could be cultured in vitro after repeated passages and differentiated into adipocytes in the presence of insulin, T3 and/or troglitazone, expressing some adipocyte-specific genes and accumulating intracellular lipid droplets. The mRNA level of uncoupling protein 1 (UCP1), a mitochondrial protein specifically present in brown adipocytes, was undetectable in HB2 preadipocytes, but increased after adipose differentiation. In HB2 adipocytes, UCP1 mRNA expression was markedly activated after stimulation of the beta-adrenergic receptor pathway. The mRNA of UCP2 and UCP3, recently cloned isoforms of UCP1, were also detected in HB2 adipocytes, but their levels were not influenced by adrenergic stimulation. Thus HB2 cells seem useful for in vitro studies of BAT and UCP functions.     

Development of Phodopus sungorus brown preadipocytes in primary cell culture: effect of an atypical beta-adrenergic agonist, insulin, and triiodothyronine on differentiation, mitochondrial development, and expression of the uncoupling protein UCP

A new cellular model for the study of brown adipocyte development and differentiation in vitro is presented. Preadipocytes isolated from brown adipose tissue (BAT) of the djungarian dwarf hamster Phodopus sungorus are able to proliferate and differentiate in vitro into true brown adipocytes able to express the BAT marker protein the uncoupling protein (UCP). Whereas basal UCP expression is very low, its mRNA levels as well as the UCP detected by immunoblotting are highly increased by beta-adrenergic stimulation. The novel, atypical beta-adrenergic compound D7114 (ICI Pharmaceuticals, Macclesfield, Cheshire, England) was found to increase the number of adipocytes as well as UCP mRNA and UCP content of mitochondria, indicating the involvement of an atypical or beta 3 receptor. Insulin was found to play an important role in brown adipocyte differentiation and mitochondrial development, whereas T3 seemed to be implicated more directly in UCP expression. In a defined, serum-free medium a synergistic stimulatory action of insulin and T3 on UCP expression was found, which seems to involve a pathway different from that of beta-adrenergic UCP stimulation.     

Effect of high-fat diet, surrounding temperature, and enterostatin on uncoupling protein gene expression

Nonshivering thermogenesis induced in brown adipose tissue (BAT) during high-fat feeding is mediated through uncoupling protein 1 (UCP1). UCP2 is a recently identified homologue found in many tissues. To determine the role of UCP1 and UCP2 in thermoregulation and energy balance, we investigated the long-term effect of high-fat feeding on mRNA levels in mice at two different ambient temperatures. We also treated mice with the anorectic peptide enterostatin and compared mRNA levels in BAT, white adipose tissue (WAT), stomach, and duodenum. Here, we report that high-fat feeding at 23 degrees C increased UCP1 and UCP2 levels in BAT four- and threefold, respectively, and increased UCP2 levels fourfold in WAT. However, at 29 degrees C, UCP1 decreased, whereas UCP2 remained unchanged in BAT and increased twofold in WAT. Enterostatin increased UCP1 and decreased UCP2 mRNA in BAT. In stomach and duodenum, high-fat feeding decreased UCP2 mRNA, whereas enterostatin increased it. Our results suggest that the regulation of uncoupling protein mRNA levels by high-fat feeding is dependent on ambient temperature and that enterostatin is able to modulate it.     

Chronic umbilical cord compression results in accelerated maturation of lung and brown adipose tissue in the sheep fetus during late gestation

Umbilical cord compression (UCC) sufficient to reduce umbilical blood flow by 30% for 3 days, results in increased fetal plasma cortisol and catecholamines that are likely to promote maturation of the fetal lung and brown adipose tissue (BAT). We determined the effect of UCC on the abundance of uncoupling protein (UCP)1 (BAT only) and -2, glucocorticoid receptor (GR), and 11beta-hydroxysteroid dehydrogenase (11beta-HSD)1 and -2 mRNA, and mitochondrial protein voltage-dependent anion channel (VDAC) and cytochrome c in these tissues. At 118 +/- 2 days of gestation (dGA; term approximately 145 days), 14 fetuses were chronically instrumented. Eight fetuses were then subjected to 3 days of UCC from 125 dGA, and the remaining fetuses were sham operated. All fetuses were then exposed to two 1-h episodes of hypoxemia at 130 +/- 1 and 134 +/- 1 dGA before tissue sampling at 137 +/- 2 dGA. In both tissues, UCC upregulated UCP2 and GR mRNA, plus VDAC and cytochrome c mitochondrial proteins. In lung, UCC increased 11beta-HSD1 mRNA but decreased 11beta-HSD2 mRNA abundance, a pattern reversed for BAT. UCC increased UCP1 mRNA and its translated protein in BAT. UCP2, GR, 11beta-HSD1 and -2 mRNA, plus VDAC and cytochrome c protein abundance were all significantly correlated with fetal plasma cortisol and catecholamine levels, but not thyroid hormone concentrations, in the lung and BAT of UCC fetuses. In conclusion, chronic UCC results in precocious maturation of the fetal lung and BAT mitochondria, an adaptation largely mediated by the surge in fetal plasma cortisol and catecholamines that accompanies UCC.     

Full expression of uncoupling protein gene requires the concurrence of norepinephrine and triiodothyronine

We have examined the uncoupling (UCP) protein gene expression in euthyroid and hypothyroid rats. UCP mRNA levels were estimated by northern blot analysis of total RNA from brown adipose tissue (BAT). Stimuli were endogenous (cold) and exogenous norepinephrine (NE), isoproterenol, T3, and T4. While the euthyroid rats UCP mRNA levels increase 2- to 3-fold by 2 h after NE or overnight cold exposure, these stimuli and isoproterenol are ineffective in hypothyroid rats. One single dose of T4, equal to the daily production rate, brings about a normal response in hypothyroid rats exposed to cold overnight. Hypothyroid rats recover their responsiveness to NE approximately 4 h after a receptor saturating dose of T3. On the other hand, such a dose of T3 induces a 3- to 4-fold increase in UCP mRNA levels in hypothyroid rats without the need of exogenous NE, and this response is not reduced by raising ambient temperature to thermoneutrality (28 C). However, the following evidence indicates that T3 requires adrenergic input to stimulate the accumulation of UCP mRNA: first, euthyroid animals maintained at 28 C do not respond to such a treatment. Second, when T3 was injected to hypothyroid rats with unilaterally denervated BAT, only the intact side responded to T3 with an elevation of the UCP mRNA levels, but both sides remained responsive to T3 + NE.(ABSTRACT TRUNCATED AT 250 WORDS)     

Expression of uncoupling protein 3 is upregulated in skeletal muscle during sepsis

Uncoupling protein 3 (UCP3) is a member of the mitochondrial transporter superfamily that is expressed primarily in skeletal muscle. UCP3 is upregulated in various conditions characterized by skeletal muscle atrophy, including hyperthyroidism, fasting, denervation, diabetes, cancer, lipopolysaccharide (LPS), and treatment with glucocorticoids (GCs). The influence of sepsis, another condition characterized by muscle cachexia, on UCP3 expression and activity is not known. We examined UCP3 gene and protein expression in skeletal muscles from rats after cecal ligation and puncture and from sham-operated control rats. Sepsis resulted in a two- to threefold increase in both mRNA and protein levels of UCP3 in skeletal muscle. Treatment of rats with the glucocorticoid receptor antagonist RU-38486 prevented the sepsis-induced increase in gene and protein expression of UCP3. The UCP3 mRNA and protein levels were increased 2.4- to 3.6-fold when incubated muscles from normal rats were treated with dexamethasone (DEX) and/or free fatty acids (FFA) ex vivo. In addition, UCP3 mRNA and protein levels were significantly increased in normal rat muscles in vivo with treatment of either DEX or FFA. The results suggest that sepsis upregulates the gene and protein expression of UCP3 in skeletal muscle, which may at least in part be mediated by GCs and FFA.     

Measurement of brown adipose tissue uncoupling protein by enzyme linked immunosorbent assay

Antibody to uncoupling protein (UCP) purified from rat brown adipose tissue (BAT) was raised in rabbits and an enzyme linked immunosorbent assay was developed. The antiserum did not cross-react with other mitochondrial proteins from BAT and from other tissues but cross-reacted with UCP from hamster, guinea pig and mouse. The assay is capable of detecting 5 ng of UCP. Using this assay and a crude mitochondrial preparation, UCP content of BAT was shown to increase during cold adaptation.     

Ghrelin affects gastrectomy-induced decrease in UCP1 and beta3-AR mRNA expression in mice

In this study we investigated the effects of gastrectomy (Gx) and of the gastric hormone, ghrelin, on the expression of proteins in brown adipose tissue (BAT) that are thought to be involved in thermogenesis. Heat production in BAT is known to depend upon activation and increased expression of beta3-adrenergic receptors (beta3-AR) and the consequent up-regulation of uncoupling protein 1 (UCP1). Mice were subjected to Gx or sham operation. One week later they started to receive daily subcutaneous injections of either saline or ghrelin (12 nmol) for two or eight weeks. Neither Gx nor ghrelin affected daily food intake. Gx did not lower body weight gain (except during the first post-operative week) but Gx mice responded to eight weeks of ghrelin treatment with a greater body weight increase (37%, p<0.05) than saline-injected Gx mice; sham-operated mice did not respond to ghrelin. Gx resulted in a greatly reduced expression of both UCP1 and beta3-AR mRNA in BAT (50% reduction or more, p<0.01) compared to sham-operated mice. Eight weeks of ghrelin treatment raised the UCP1 as well as the beta3-AR mRNA expression in the Gx mice, whereas two weeks of ghrelin treatment decreased UCP1 and beta3-AR mRNA expression compared to Gx mice receiving saline. In fact, mRNA expression in Gx mice after treatment with ghrelin for eight weeks was similar to that in saline-treated sham-operated mice. Ghrelin did not affect UCP1 and beta3-AR mRNA in sham-operated mice neither two nor eight weeks after the operation. The results suggest 1) that signals from the stomach stimulate BAT UCP1 (and possibly thermogenesis) and 2) that ghrelin may contribute to the control of UCP1 expression.     

Opposite regulation of uncoupling protein 1 and uncoupling protein 3 in vivo in brown adipose tissue of cold-exposed rats

Earlier we reported a 14-fold increase of glycogen in the brown adipose tissue (BAT) in rats when the animals were placed back from cold to neutral temperature. To elucidate the mechanism, here we compared the level of glucose transporter 4 (GLUT4) protein, uncoupling protein (UCP) 1 and UCP3 mRNA and protein expressions in the BAT under the same conditions. We found that the increased GLUT4 level in cold was maintained during the reacclimation. After 1 week cold exposure the mRNA and protein content of UCP1 increased parallel, while the protein level of UCP3 decreased, contrary to its own mRNA level.     

Acute cold exposure-induced down-regulation of CIDEA, cell death-inducing DNA fragmentation factor-α-like effector A, in rat interscapular brown adipose tissue by sympathetically activated β3-adrenoreceptors

The thermogenic activity of brown adipose tissue (BAT) largely depends on the mitochondrial uncoupling protein 1 (UCP1), which is up-regulated by environmental alterations such as cold. Recently, CIDEA (cell death-inducing DNA fragmentation factor-α-like effector A) has also been shown to be expressed at high levels in the mitochondria of BAT. Here we examined the effect of cold on the mRNA and protein levels of CIDEA in interscapular BAT of conscious rats with regard to the sympathetic nervous system. Cold exposure (4 °C for 3 h) elevated the plasma norepinephrine level and increased norepinephrine turnover in BAT. Cold exposure resulted in down-regulation of the mRNA and protein levels of CIDEA in BAT, accompanied by up-regulation of mRNA and protein levels of UCP1. The cold exposure-induced changes of CIDEA and UCP1 were attenuated by intraperitoneal pretreatment with propranolol (a non-selective β-adrenoreceptor antagonist) (2 mg/animal) or SR59230A (a selective β₃-adrenoreceptor antagonist) (2 mg/animal), respectively. These results suggest that acute cold exposure resulted in down-regulation of CIDEA in interscapular BAT by sympathetically activated β₃-adrenoreceptor-mediated mechanisms in rats.     

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.

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.