![[Feedback]](/icons/banner/feedbackACT.gif){kind=icon}
![[For Subscribers]](/icons/banner/subscriberACT.gif){kind=icon}
![[Archive]](/icons/banner/archiveACT.gif){kind=icon}
![[Search]](/icons/banner/searchACT.gif){kind=icon}
![[Contents]](/icons/banner/tocACT.gif){kind=icon}
|
|
|
|
|
||
| |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Vol. 305, Issue 1, 167-172, April 2003
-Hydroxysteroid Dehydrogenase Type 1 a Therapeutic
Target? Effects of Carbenoxolone in Lean and Obese Zucker Rats
Endocrinology Unit, Department of Medical Sciences, University of Edinburgh, Western General Hospital, Edinburgh, United Kingdom
 |
Abstract |
|---|
 Top
 Abstract
 Introduction
Materials and Methods
Results
Discussion
References
|
|---|
In liver and adipose tissue, 11
-hydroxysteroid dehydrogenase type 1 (11-HSD1) regenerates glucocorticoids from inactive 11-keto
metabolites. Pharmacological inhibition or transgenic disruption
of 11-HSD1 attenuates glucocorticoid action and increases insulin
sensitivity. Increased adipose 11-HSD1 may also contribute to the
metabolic complications of obesity. Here, we examine the effects of
inhibition of 11-HSDs with carbenoxolone in obese insulin-resistant
Zucker rats, a strain in which tissue-specific dysregulation of
11-HSD1 (increased in adipose, decreased in liver) mirrors changes
in human obesity. Six-week-old male rats were treated orally with
carbenoxolone (50 mg/kg/day) or water (1 ml/kg/day) for 3 weeks.
Carbenoxolone inhibited 11-HSD1 activity in liver (25 ± 3 versus 52 ± 2% conversion in lean; 18 ± 3 versus 35 ± 3% in obese; p < 0.01) but not in adipose
tissue or skeletal muscle. Carbenoxolone had no effect on weight gain
or food intake, did not affect plasma glucose during an oral glucose
tolerance test, and increased the plasma insulin response to glucose.
However, high-density lipoprotein cholesterol was increased by
carbenoxolone in obese animals (1.52 ± 0.24 versus 1.21 ± 0.26 mM; p < 0.03). Carbenoxolone did not inhibit
hepatic inactivation of glucocorticoid by 5-reductase and had no
significant effect on plasma corticosterone levels. In conclusion,
carbenoxolone provides a model for liver-specific inhibition of
11-HSD1, which results in improved lipid profile, in Zucker obese
rats. Failure to inhibit 11-HSD1 in adipose tissue and/or skeletal
muscle may explain the lack of effect on glucose tolerance and obesity.
Inhibition of adipose 11-HSD1 is probably necessary to gain the
maximum benefit of an 11-HSD1 inhibitor.
| |
Introduction |
|---|
|
Top
Abstract
Introduction
Materials and Methods
Results
Discussion
References
|
|---|
Increased
activation of glucocorticoid receptors (e.g., in Cushing's syndrome)
results in insulin resistance and central obesity. Conversely,
adrenalectomy or glucocorticoid receptor antagonists prevent obesity in
rodents (Friedman et al., 1993
). Access of steroid ligands to
glucocorticoid receptors depends not only on the levels circulating in
the blood but also on prereceptor metabolism, particularly by the
isozymes of 11-hydroxysteroid dehydrogenase (11-HSD). In
mineralocorticoid target tissues, such as the distal nephron, 11-HSD
type 2 inactivates glucocorticoids (cortisol in humans; corticosterone
in rodents) to their 11-keto metabolites (cortisone and
11-dehydrocorticosterone, respectively), thus preventing binding of
glucocorticoids to mineralocorticoid receptors (Stewart and Krozowski,
1999). In contrast, in glucocorticoid target tissues such as liver
(Jamieson et al., 1995) and adipose tissue (Bujalska et al., 1997),
11-HSD type 1 (11-HSD1) catalyzes the reactivation of
glucocorticoids from inert 11-keto forms, thus increasing local glucocorticoid concentrations (Seckl and Walker, 2001).
Loss of 11-HSD1 activity, by either pharmacological inhibition or
targeted gene disruption, prevents regeneration of glucocorticoid. The
resultant decrease in glucocorticoid action probably accounts for the
observed increased insulin sensitivity (Walker et al., 1995), decreased
gluconeogenic responses to fasting and stress (Kotelevtsev et al.,
1997; Jamieson et al., 1998), and cardioprotective lipid profile
(Morton et al., 2001). These metabolic benefits of 11-HSD1
inhibition occur despite normal, or even increased (Kotelevtsev et al.,
1997; Harris et al., 2001), circulating glucocorticoid levels.
11-HSD1 inhibition may also be useful in the pancreatic -cells,
where regeneration of glucocorticoid by 11-HSD1 may inhibit insulin
secretion (Davani et al., 2000). Furthermore, beneficial effects of
inhibiting 11-HSD1 in adipose tissue have been predicted from in
vitro studies (Bujalska et al., 1999; Handoko et al., 2000).
Against this background, inhibition of 11-HSD1 has been proposed as
a novel therapeutic strategy in insulin resistance syndromes, including
obesity (Walker et al., 1995; Bujalska et al., 1997; Seckl and Walker,
2001). The potential importance of this strategy is reinforced by
reports of tissue-specific alterations in 11-HSD1 in these
syndromes. In leptin-resistant obese Zucker rats (Livingstone et al.,
2000a), and in human idiopathic obesity (Stewart et al., 1999; Rask et
al., 2001; Rask et al., 2002), hepatic 11-HSD1 activity is reduced
while adipose 11-HSD1 activity is increased. In contrast, in other
insulin resistance syndromes, including myotonic dystrophy (Johansson
et al., 2001), hepatic 11-HSD1 activity is increased. The mechanism
is not understood, but it presumably reflects tissue-specific
regulation of 11-HSD1 gene expression by metabolic signals,
including insulin, cytokines, and growth factors (Handoko et al., 2000;
Livingstone et al., 2000b; Tomlinson et al., 2001). A similar magnitude
of increased adipose 11-HSD1 activity in adipose, produced by
transgenic overexpression of rat 11-HSD1 in mouse adipose under the
Ap2 promoter, resulted in dramatic central obesity, insulin resistance,
diabetes mellitus, and dyslipidemia (Masuzaki et al., 2001).
In this article, we compare the effects of inhibiting 11-HSD1 in
lean and obese Zucker rats, to establish the metabolic effects of in
vivo pharmacological manipulation of 11-HSD1 in rodents, and to
assess the importance of tissue-specific changes in 11-HSD1 activity
on the therapeutic response in obesity. In the absence of a selective
11-HSD1 inhibitor, we administered carbenoxolone, a derivative of
liquorice that inhibits both isozymes of 11-HSD in vivo (Stewart et
al., 1990; Jellinck et al., 1993).
| |
Materials and Methods |
|---|
|
Top
Abstract
Introduction
Materials and Methods
Results
Discussion
References
|
|---|
Animals. All experiments were carried out humanely under UK Home Office animal license. Groups of eight 5-week-old male obese and lean Zucker rats (Harlan Orlac, Bicester, UK) were characterized by phenotype, maintained under controlled conditions of light (on from 8:00 AM to 8:00 PM) and temperature (21°C), and allowed free access to standard rat chow (Special Diet Services, Witham, UK) and drinking water.
Drug treatment was commenced when the animals were 6 weeks of age. Carbenoxolone (50 mg/kg b.wt.) or a matched volume of vehicle (water; 1 ml/kg/day) was administered by gavage daily at 9:00 AM. Animals were weighed regularly to allow accurate dosing with drugs and to follow the progress of weight gain. Food intake for each cage of four animals was measured daily. After 2 weeks of treatment animals underwent an oral glucose tolerance test, which consisted of an overnight fast, followed by an oral glucose load of 2g/kg b.wt. at 9:00 AM. Blood samples were taken by tail-nick at 0, 30, and 120 min after the glucose bolus. At 9 weeks of age (i.e., after 3 weeks of carbenoxolone or vehicle treatment), animals were decapitated at 9:00 to 11:00 AM, trunk blood was collected, and tissues were dissected and either snap-frozen on dry ice or mechanically homogenized in Krebs-bicarbonate Ringer buffer (118 mM NaCl, 3.8 mM KCl, 1.19 mM KH2PO4, 2.54 mM CaCl2, 1.19 mM MgSO4, and 25 mM NaHCO3, pH 7.4).Plasma Assays. Corticosterone levels were measured in plasma prepared from terminal blood samples collected at 9:00 to 11:00 AM using an in-house radioimmunoassay. The inter- and intra-assay coefficients of variation were <10%.
Glucose concentrations were determined using a hexokinase glucose assay kit (Sigma-Aldrich Company Ltd., Poole, Dorset, UK) for which the inter- and intra-assay coefficients of variation were both <2%. Insulin was measured using a rat 125I-insulin radioimmunoassay kit (Amersham Biosciences UK, Ltd., Little Chalfont, Buckinghamshire, UK), for which the inter- and intra-assay coefficients of variation were <15 and <10%, respectively. Lipid levels were measured in plasma prepared from terminal blood samples collected at 9:00 to 11:00 AM. Triglycerides, total cholesterol and HDL cholesterol were measured using enzyme-linked immunosorbent assay kits (TG, CHOL, and HDL C-plus, respectively) from Roche Diagnostics (Mannheim, Germany). Nonesterified fatty acids (NEFAs) were measured using the Wako NEFA C enzymatic assay (Alpha Laboratories Ltd., Hampshire, UK).Measurement of Enzyme Activities in Vitro.
In vivo,
11-HSD1 functions as a reductase, reactivating corticosterone from
inactive 11-dehydrocorticosterone (Jamieson et al., 1995; Bujalska et
al., 1997). However, in tissue homogenates dehydrogenase activity
predominates, so 11-HSD1 activity was assessed by conversion of
corticosterone to 11-dehydrocorticosterone. Both reaction directions
are inhibited by carbenoxolone.
-HSD1 activity was measured in homogenates of tissues by
incubating in duplicate at 37°C, in Krebs-Ringer buffer containing glucose (0.2%), NADP (2 mM), and
1,2,6,7-[3H4]corticosterone
(100 nM). Conditions were optimized for each tissue to ensure first
order kinetics, by adjusting protein concentrations as follows: 10 µg/ml for liver, 1.5 mg/ml for quadriceps skeletal muscle, 0.5 mg/ml
for subcutaneous lumbar fat, and 1 mg/ml for omental fat. After 60-min
incubation, steroids were extracted with ethyl acetate, the organic
phase was evaporated under nitrogen, and extracts resuspended in mobile
phase (20% methanol, 30% acetonitrile, and 50% water). Steroids were
separated by HPLC using a reverse phase µ-Bondapak
C18 column at 20°C and quantified by on-line liquid scintillation counting. No peaks other than
[3H]corticosterone and
[3H]11-dehydrocorticosterone were detected
under these conditions.
11-HSD2 activity in the kidney was determined in a similar way, with
homogenates (protein concentration 50 µg/ml) incubated with 10 nM
[3H]corticosterone and NAD (2 mM) as cofactor.
Steroids were extracted with ethyl acetate and separated by HPLC as
described above.
5-Reductase activity in the liver was assessed by the conversion of
[3H]corticosterone to
[3H]5-tetrahydrocorticosterone in liver
cytosol preparations. The subcellular localization and cofactor
preference of 11-HSD1 and 5-reductase differ such that the enzyme
activities can be measured independently of one another. Liver cytosol
was prepared by repeated centrifugation according to the method of
Fleischer and Kervina (1974). Enzyme activity was measured by
incubating cytosol (100 µg of protein/ml) in duplicate at 37°C, in
phosphate buffer (40 mM
Na2PO4, 320 mM sucrose, and
1 mM dithiothreitol, pH 7.5) containing NADPH (1 mM) and
[3H]corticosterone (150 nM). Incubations were
carried out for 60 min, after which steroids were extracted with ethyl
acetate, the organic phase evaporated under nitrogen and extracts were
resuspended in mobile phase (25% methanol, 10% acetonitrile, and 65%
water). Steroids were separated by HPLC using a reverse phase
C8 column at 10°C, and quantified by on-line
liquid scintillation counting. Under these conditions, production of
[3H]11-dehydrocorticosterone was below the
limit of detection (i.e., <2%).
Radiolabeled-steroids were from Amersham Biosciences UK, Ltd. Solvents
were HPLC glass-distilled grade from Rathburn Chemicals (Walkerburn,
UK). Other chemicals were from Sigma-Aldrich Company Ltd.
Statistics. All data are expressed as mean ± standard error. Data were analyzed by analysis of variance followed by post hoc least-squares difference tests. n = 8 for all groups.
| |
Results |
|---|
|
Top
Abstract
Introduction
Materials and Methods
Results
Discussion
References
|
|---|
Obesity.
Vehicle-treated obese Zucker rats had higher food
consumption and gained more weight in the 3-week treatment period than
lean animals (Table 1). Carbenoxolone
treatment had no effect on food intake or body weight in either lean or
obese animals.
|
Oral Glucose Tolerance.
In vehicle-treated rats, obese
animals had relative hyperglycemia and hyperinsulinemia both on fasting
and after glucose (Fig. 1). Carbenoxolone
treatment had no significant effect on plasma glucose in either group.
In contrast, carbenoxolone increased plasma insulin in the fasting
state in both lean and obese animals. Insulin was also higher in
carbenoxolone-treated obese animals at 30 min and in lean animals at
120 min after glucose bolus.
|
Nonfasting Plasma Lipid Levels.
Total cholesterol was higher
in obese than in lean rats, but was not affected by carbenoxolone (Fig.
2). In contrast, HDL cholesterol was not
different between lean and obese rats and was increased by
carbenoxolone in obese animals. Triglycerides were higher in obese than
in lean rats and were reduced by carbenoxolone treatment in obese
animals. Nonfasting plasma NEFAs were not different between any of the
groups.
|
11-HSD Activities in Vitro.
Among vehicle-treated rats,
tissue-specific dysregulation of 11-HSD1 activity in obesity was
confirmed (Livingstone et al., 2000a), such that obese animals had
lower activity in liver but higher activity in omental adipose tissue
(Fig. 3). Carbenoxolone administration
resulted in similar measurable ex vivo inhibition of hepatic 11-HSD1
and renal 11-HSD2 activities in lean and obese animals. In contrast,
carbenoxolone administration did not affect ex vivo 11-HSD1 activity
in skeletal muscle or adipose tissue.
|
Hypothalamic Pituitary Adrenal (HPA) Axis. In vehicle-treated rats, adrenal weight was higher in obese animals than in lean (Table 1). Carbenoxolone treatment had no effect on adrenal weight in lean animals, but it ameliorated adrenal hypertrophy in obese rats.
Plasma corticosterone levels were variable, probably reflecting uncontrolled stress at the time of decapitation. There were no statistically significant differences in plasma corticosterone levels, but there was a trend for plasma corticosterone to be higher in obese than lean animals (Table 1) and for carbenoxolone to increase plasma corticosterone in both groups.5-Reductase Activity in Vitro.
Glycyrrhetinic acid, from
which carbenoxolone is derived, has been reported to inhibit other
steroid-metabolizing enzymes, including 5-reductase (Latif et al.,
1990). 5-Reductase irreversibly reduces the A-ring of
glucocorticoids, thus inactivating them. Hepatic 5-reductase
activity was higher in obese animals than lean (Fig.
4). Carbenoxolone, rather than inhibiting
5-reductase, exacerbated the increase in obese animals.
|
| |
Discussion |
|---|
|
Top
Abstract
Introduction
Materials and Methods
Results
Discussion
References
|
|---|
Loss of 11-HSD1 activity in knockout mice (Kotelevtsev et al.,
1997), after down-regulation with estradiol in male rats (Jamieson et
al., 1998), or after pharmacological inhibition with carbenoxolone in
healthy men (Walker et al., 1995), is associated with evidence of
reduced intrahepatic glucocorticoid receptor activation. This is
reflected in decreased expression of gluconeogenic enzymes with lower
fasting blood glucose levels, and increased lipid oxidation with lower
triglyceride and higher HDL cholesterol levels (Morton et al., 2001).
Improved glucose tolerance in 11-HSD1 knockout mice (Morton et al.,
2001), and increased insulin sensitivity during hyperinsulinaemic
euglycemic clamps in humans (Walker et al., 1995), is also consistent
with increased insulin sensitivity in peripheral tissues, such as fat,
resulting in increased peripheral glucose uptake.
Considering the above-mentioned evidence, we hypothesized that
carbenoxolone treatment of obese Zucker rats would decrease intracellular glucocorticoid levels in tissues expressing 11-HSD1 and hence improve insulin sensitivity, reduce obesity, and improve the
plasma lipid profile. This article provides evidence in partial support
of this hypothesis. Carbenoxolone treatment resulted in tissue-specific
inhibition of 11-HSDs, with reduced enzyme activity in liver and
kidney, but not in the key glucocorticoid targets of muscle and fat.
Consistent with this pattern, carbenoxolone improved the plasma lipid
profile, but not glucose tolerance, insulin sensitivity, or body weight.
In lean rats, carbenoxolone had no significant effect on fasting blood
glucose, glucose tolerance, or nonfasting plasma lipid profile, and
increased rather than decreased plasma insulin levels. It is possible
that carbenoxolone might alter insulin secretion due to decreased
glucocorticoid concentrations with the pancreatic -cell (Davani et
al., 2000). However, the relative hyperinsulinemia occurred in the face
of normal glucose concentrations and was not apparent 30 min after a
glucose load, suggesting that it reflects insulin resistance rather
than primary stimulation of insulin secretion.
We considered a number of possible explanations for the failure to
improve insulin sensitivity with carbenoxolone in lean rats. First, we
sought to confirm the efficacy of inhibition of 11-HSD1.
Importantly, despite substantial inhibition of 11-HSD2 in kidney and
of 11-HSD1 in liver, carbenoxolone did not inhibit enzyme activity
in skeletal muscle or adipose tissue, sites where glucocorticoids
influence peripheral glucose uptake (Andrews and Walker, 1999). The
homogenization and incubation of these tissues was similar, making
excessive dilution of inhibitor in vitro an unlikely explanation.
Indeed, adipose tissue and muscle were the least diluted of the tissues
examined, and so would be predicted to have the highest remaining
concentration of carbenoxolone. We also considered whether endogenous
corticosterone concentrations would affect 11-HSD1 activity in
vitro, but the assay conditions are such that the concentration of
added [3H]corticosterone (100 nM) is likely to
be substantially higher than the endogenous free corticosterone
remaining in the assay after substantial dilution of the original
material. Moreover, the same assays performed in tissues from
adrenalectomized rats do not show artifactual changes in apparent
11-HSD1 activity (Livingstone et al., 2000b). Although carbenoxolone
is known to inhibit adipose tissue 11-HSD activity in vitro
(Yang et al., 1997) to our knowledge, no previous studies with systemic
administration of 11-HSD inhibitors have examined enzyme activity in
these tissues. It seems likely that the lack of effect of carbenoxolone
in adipose tissue and muscle reflects a pharmacokinetic problem with
access of the relatively water-soluble carbenoxolone to these tissues. Second, we considered other influences of carbenoxolone on
intracellular glucocorticoid levels. Glycyrrhetinic acid, from which
carbenoxolone is derived, inhibits 5-reductase (Latif et al., 1990)
and if the same was true for carbenoxolone this would limit a major
pathway for inactivation of glucocorticoid in the liver. However, we
found that carbenoxolone did not alter 5-reduction of corticosterone in lean rats. Third, we considered whether carbenoxolone alters circulating glucocorticoid levels. Any effect of carbenoxolone on
plasma corticosterone levels is hard to predict because it will depend
on the balance of inhibition of inactivation of glucocorticoid in the
kidney by 11-HSD2, inhibition of reactivation of glucocorticoid in
the liver by 11-HSD1, and potentially altered negative feedback in
the HPA axis where 11-HSD1 is expressed (Harris et al., 2001). In
lean animals here, adrenal weight was not altered by carbenoxolone, although there was a tendency for higher plasma corticosterone levels
after carbenoxolone treatment. However, by analogy with the 11-HSD1
knockout mouse, modest elevation of plasma corticosterone is unlikely
to be sufficient to overcome the influence of 11-HSD1 regeneration
of glucocorticoid within the liver (Harris et al., 2001; Morton et al.,
2001).
We conclude that the most likely explanation for the lack of effect of
carbenoxolone on metabolic parameters in lean rats is the failure of
the drug to inhibit 11-HSD1 in adipose tissue. This could explain a
lack of effect on peripheral glucose uptake, the principal determinant
of glucose tolerance. Very recently, we have administered carbenoxolone
to humans with type 2 diabetes and shown similar liver-specific effects
on insulin sensitivity and lipid profile (Andrews et al., 2003). It is
noteworthy that a striking improvement in insulin sensitivity and
glucose tolerance during high-fat feeding is observed with loss of
11-HSD1 in the 11-HSD1 knockout mouse (Kotelevtsev et al., 1997).
In this model there is a lack of 11-HSD1 in all tissues, and it may
be that the effects on insulin sensitivity are largely due to effects in adipose tissue and muscle. Recent publications also demonstrate decreased plasma glucose concentrations with a novel selective 11-HSD1 inhibitor in diabetic mice (Alberts et al., 2002; Barf et
al., 2002). Although these investigators confirmed inhibition of
11-HSD1 by their inhibitor in liver, they did not report its effects
in other tissues. From the current data, we suspect that, unlike
carbenoxolone, the novel 11-HSD1 inhibitor acts on the enzyme in
adipose and/or muscle and exerts its effect through increased
peripheral glucose uptake.
It is also emerging that signaling between adipose tissue and liver is
crucial in determining hepatic insulin sensitivity (Dale et al., 2001).
In addition to recently recognized mediators of this signaling
(including free fatty acids, resistin, adiponectin, and tumor necrosis
factor-
) it seems that adipose generation of glucocorticoid within
the mesenteric portal circulation is crucial to determining
intrahepatic glucocorticoid levels, as originally hypothesized by
Bujalska et al. (1997) and confirmed in mice with adipose-specific
11-HSD1 overexpression, which exhibit glucose intolerance and
insulin resistance (Masuzaki et al., 2001). Inadvertently, this
experiment with carbenoxolone has produced the first model of
relatively tissue-specific hepatic manipulation of 11-HSD1. Further
exploration of the relative importance of liver and adipose 11-HSD1
activities in determining the metabolic profile of rodents and humans
will be intriguing.
In obese animals, we confirmed that 11-HSD1 is increased in
adipose tissue and decreased in liver, as described previously in rat
and human obesity (Livingstone et al., 2000a, Rask et al., 2001, 2002).
As in lean rats, carbenoxolone was effective in inhibiting 11-HSD1
activity in liver and 11-HSD2 activity in kidney, but it did not
inhibit 11-HSD1 activity in skeletal muscle or adipose tissue. This
illustrates that further reduction in hepatic 11-HSD1 activity can
be achieved pharmacologically in obese animals, beyond their basal
down-regulation of enzyme activity. As in the lean rats, carbenoxolone
had no effect on fasting plasma glucose or glucose tolerance. However,
in the obese rats carbenoxolone did induce the same cardioprotective
pattern of altered lipid profile (with decreased triglycerides and
increased HDL cholesterol), which has been observed in the 11-HSD1
knockout mouse (Morton et al., 2001). In the mouse model, this has been
attributed to enhanced hepatic lipid oxidation rather than altered
adipose metabolism, and probably results from up-regulation of
peroxisome proliferator-activated receptor in liver (Morton et al.,
2001). A further lesson from the 11-HSD1 knockout mouse is that
differences in hepatic glucose metabolism were elicited only during
dynamic testing (fasting and overfeeding; Kotelevtsev et al., 1997),
whereas differences in lipid profile were more readily apparent. It may
be that dynamic tests of hepatic glucose metabolism would reveal more
subtle effects of carbenoxolone in the liver.
Other effects of carbenoxolone were also different in obese
compared with lean animals. The HPA axis is activated in obese Zucker
rats, and adrenocortical hypertrophy and hypercorticosteronemia have
been consistent findings (Bestetti et al., 1990). The adrenal hypertrophy but not the hypercorticosteronemia was ameliorated by
carbenoxolone in this experiment. This is most readily explained by the
inhibition of renal 11-HSD2 inactivation of corticosterone, resulting in compensatory down-regulation of glucocorticoid secretion, as has been observed in humans given carbenoxolone (Stewart et al.,
1990). 5-Reductase activity was increased in obese animals relative
to lean, which may contribute to increased metabolic clearance of
corticosterone and compensatory activation of the hypothalamic-pituitary-adrenal axis.
In summary, these data suggest that inhibition of 11-HSD1 with
carbenoxolone in liver has beneficial effects on hepatic lipid metabolism in Zucker obese rats, even in the face of lower basal 11-HSD1 "target" activity. The lack of effect on glucose
tolerance may reflect failure to inhibit 11-HSD1 in adipose tissue.
If inhibition of 11-HSD1 is to be a successful therapy in obesity and diabetes mellitus, it is likely that inhibitors will need to be not
only selective for 11-HSD1 over 11-HSD2 but also be effective in
adipose tissue as well as liver.
| |
Acknowledgments |
|---|
We thank Dr. Philip Wenham (Clinical Biochemistry, Western General Hospital, Edinburgh, UK) for measuring lipids and Dr. Chris Kenyon for valuable advice.
| |
Footnotes |
|---|
Accepted for publication December 30, 2002.
Received for publication September 25, 2002.
This work was supported by grants from the Wellcome Trust and
British Heart Foundation. Part of this work has been presented previously in abstract form [Livingstone DEW and Walker BR (2001) 11-HSD1 as a therapeutic target in obesity: effects of carbenoxolone in lean and obese Zucker rats. J Endocrinol
168 (Suppl):37].
DOI: 10.1124/jpet.102.044842
Address correspondence to: Prof. Brian R. Walker, Endocrinology Unit, Department of Medical Sciences, University of Edinburgh, Western General Hospital, Edinburgh EH4 2XU, UK. E-mail: b.walker{at}ed.ac.uk
| |
Abbreviations |
|---|
11-HSD, 11-hydroxysteroid dehydrogenase;
11-HSD1, 11-hydroxysteroid dehydrogenase type 1;
HDL, high-density lipoprotein;
NEFA, nonesterified fatty acid;
HPLC, high-performance liquid chromatography;
HPA, hypothalamic-pituitary-adrenal.
| |
References |
|---|
|
Top
Abstract
Introduction
Materials and Methods
Results
Discussion
References
|
|---|
-hydroxysteroid dehydrogenase type 1 decreases blood glucose concentrations in hyperglycaemic mice.
Diabetologia
45:
1528-1542[CrossRef][Medline].-hydroxysteroid dehydrogenase inhibitor carbenoxolone on insulin sensitivity in men with type 2 diabetes.
J Clin Endocrinol Metab
88:
285-291-hydroxysteroid dehydrogenase type 1.
J Med Chem
45:
3813-3815[CrossRef][Medline].-hydroxysteroid dehydrogenase.
Endocrinology
140:
3188-3196-hydroxysteroid dehydrogenase mediates glococorticoid activation and insulin release in pancreatic islets.
J Biol Chem
275:
34841-34844 on 11-hydroxysteroid dehydrogenase 1 in human adipose stromal cells.
J Steroid Biochem Mol Biol
72:
163-168[CrossRef][Medline].-Hydroxysteroid dehydrogenase type 1 null mice have altered hypothalamic-pituitary-adrenal axis activity: a novel control of glucocorticoid feedback.
Endocrinology
142:
114-120-Hydroxysteroid dehydrogenase is an exclusive 11-reductase in primary cultures of rat hepatocytes: effect of physicochemical and hormonal manipulations.
Endocrinology
136:
4754-4761[Abstract].-hydroxysteroid dehydrogenase type 1.
J Endocrinol
160:
103-109.-hydroxysteroid dehydrogenase by carbenoxolone in rat brain regions and peripheral tissues.
J Steroid Biochem Mol Biol
46:
209-213[CrossRef][Medline].-Hydroxysteroid dehydrogenase type 1 knockout mice show attenuated glucocorticoid inducible responses and resist hyperglycaemia on obesity and stress.
Proc Natl Acad Sci USA
94:
14924-14929- and 3-hydroxysteroid dehydrogenases and 5- and 5-reductase pathways of metabolism of aldosterone in male rats.
Steroids
55:
52-58[CrossRef][Medline].-hydroxysteroid dehydrogenase type 1 in Zucker obese rats.
J Endocrinol
167:
533-539[Abstract].-hydroxysteroid dehydrogenase type 1 null mice.
J Biol Chem
276:
41293-41300-Hydroxysteroid dehydrogenase type 1 activity.
J Clin Endocrinol Metab
87:
3330-3336-Hydroxysteroid dehydrogenase type 1
a tissue-specific amplifier of glucocorticoid action.
Endocrinology
142:
1371-1376-Hydroxysteroid dehydrogenase.
Vitam Horm
57:
249-324[Medline].-hydroxysteroid dehydrogenase activity in man.
Clin Sci
78:
49-54[Medline].-hydroxysteroid dehydrogenase type 1 in adipose tissue: tissue-specific induction by cytokines.
Endocrinology
142:
1982-1989-Hydroxysteroid dehydrogenase 1 activity and gene expression in human adipose stromal cells: effect on aromatase activity.
J Steroid Biochem Mol Biol
60:
247-253[CrossRef][Medline].
This article has been cited by other articles:
|
|
 |
|
  Y. Liu, Y. Nakagawa, Y. Wang, L. Liu, H. Du, W. Wang, X. Ren, K. Lutfy, and T. C Friedman Reduction of hepatic glucocorticoid receptor and hexose-6-phosphate dehydrogenase expression ameliorates diet-induced obesity and insulin resistance in mice J. Mol. Endocrinol., August 1, 2008; 41(2): 53 - 64. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 D. P Macfarlane, S. Forbes, and B. R Walker Glucocorticoids and fatty acid metabolism in humans: fuelling fat redistribution in the metabolic syndrome J. Endocrinol., May 1, 2008; 197(2): 189 - 204. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 A. M. Nuotio-Antar, D. L. Hachey, and A. H. Hasty Carbenoxolone treatment attenuates symptoms of metabolic syndrome and atherogenesis in obese, hyperlipidemic mice Am J Physiol Endocrinol Metab, December 1, 2007; 293(6): E1517 - E1528. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
D. Qi and B. Rodrigues Glucocorticoids produce whole body insulin resistance with changes in cardiac metabolism Am J Physiol Endocrinol Metab, March 1, 2007; 292(3): E654 - E667. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 S. Nammi, K. Dembele, and B. L. G. Nyomba Increased 11beta-hydroxysteroid dehydrogenase type-1 and hexose-6-phosphate dehydrogenase in liver and adipose tissue of rat offspring exposed to alcohol in utero Am J Physiol Regulatory Integrative Comp Physiol, March 1, 2007; 292(3): R1101 - R1109. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
K Vagnerova, M Kverka, P Klusonova, P Ergang, I Miksik, H Tlaskalova-Hogenova, and J Pacha Intestinal inflammation modulates expression of 11{beta}-hydroxysteroid dehydrogenase in murine gut. J. Endocrinol., November 1, 2006; 191(2): 497 - 503. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 A. Hermanowski-Vosatka, J. M. Balkovec, K. Cheng, H. Y. Chen, M. Hernandez, G. C. Koo, C. B. Le Grand, Z. Li, J. M. Metzger, S. S. Mundt, et al. 11{beta}-HSD1 inhibition ameliorates metabolic syndrome and prevents progression of atherosclerosis in mice J. Exp. Med., August 15, 2005; 202(4): 517 - 527. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
I. J Bujalska, N. Draper, Z. Michailidou, J. W Tomlinson, P. C White, K. E Chapman, E. A Walker, and P. M Stewart Hexose-6-phosphate dehydrogenase confers oxo-reductase activity upon 11{beta}-hydroxysteroid dehydrogenase type 1 J. Mol. Endocrinol., June 1, 2005; 34(3): 675 - 684. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 K. N. Hewitt, E. A. Walker, and P. M. Stewart Minireview: Hexose-6-Phosphate Dehydrogenase and Redox Control of 11{beta}-Hydroxysteroid Dehydrogenase Type 1 Activity Endocrinology, June 1, 2005; 146(6): 2539 - 2543. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
G. Apostolova, R. A. S. Schweizer, Z. Balazs, R. M. Kostadinova, and A. Odermatt Dehydroepiandrosterone inhibits the amplification of glucocorticoid action in adipose tissue Am J Physiol Endocrinol Metab, May 1, 2005; 288(5): E957 - E964. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 T. C. Sandeep, R. Andrew, N. Z.M. Homer, R. C. Andrews, K. Smith, and B. R. Walker Increased In Vivo Regeneration of Cortisol in Adipose Tissue in Human Obesity and Effects of the 11{beta}-Hydroxysteroid Dehydrogenase Type 1 Inhibitor Carbenoxolone Diabetes, March 1, 2005; 54(3): 872 - 879. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 R. A. S. Schweizer, M. Zurcher, Z. Balazs, B. Dick, and A. Odermatt Rapid Hepatic Metabolism of 7-Ketocholesterol by 11{beta}-Hydroxysteroid Dehydrogenase Type 1: SPECIES-SPECIFIC DIFFERENCES BETWEEN THE RAT, HUMAN, AND HAMSTER ENZYME J. Biol. Chem., April 30, 2004; 279(18): 18415 - 18424. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
N. M. Morton, J. M. Paterson, H. Masuzaki, M. C. Holmes, B. Staels, C. Fievet, B. R. Walker, J. S. Flier, J. J. Mullins, and J. R. Seckl Novel Adipose Tissue-Mediated Resistance to Diet-Induced Visceral Obesity in 11{beta}-Hydroxysteroid Dehydrogenase Type 1-Deficient Mice Diabetes, April 1, 2004; 53(4): 931 - 938. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
K. R. Steffensen and J.-A. Gustafsson Putative Metabolic Effects of the Liver X Receptor (LXR) Diabetes, February 1, 2004; 53(90001): S36 - 42. [Abstract] [Full Text]
|
|
|
|
 |
|
 J. R. Seckl, N. M. Morton, K. E. Chapman, and B. R. Walker Glucocorticoids and 11beta-Hydroxysteroid Dehydrogenase in Adipose Tissue Recent Prog. Horm. Res., January 1, 2004; 59(1): 359 - 393. [Abstract] [Full Text]
|
|
|
|
 |
|
 D. S. Weigle Pharmacological Therapy of Obesity: Past, Present, and Future J. Clin. Endocrinol. Metab., June 1, 2003; 88(6): 2462 - 2469. [Full Text] [PDF]
|
|
| |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
 |
 |
 |
|
 |
 |
 |
, p < 0.05 compared with vehicle-treated
group of the same phenotype.
