| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
Other Original Articles |
Division of Medical Sciences, Department of Medicine, University of Birmingham, Queen Elizabeth Hospital, Birmingham, United Kingdom B15 2TH
Address all correspondence and requests for reprints to: Dr. P. G. McTernan Anderson, Department of Medicine, Clinical Research Block, Queen Elizabeth Hospital, Edgbaston, Birmingham, United Kingdom B15 2TH. E-mail: p.g.mcternan.2D{at}bham.ac.uk
Abstract
The gender-specific differences in body fat distribution suggest that sex steroids play an important role in regulating body fat distribution. Sex steroids may regulate adipose tissue mass by altering adipocyte number and size. The effects of various sex steroids on in vitro proliferation of preadipocytes from both sc and omental fat depots was investigated in men and women. Abdominal sc and omental preadipocytes from men (n = 14) and women (8 premenopausal and 7 postmenopausal) were cultured in the presence of 17ß-E2 (10-7–10-9 M), estrone (10-7–10-9 M), or dehydrotestosterone (DHT) (10-7–10-9 M), and the rate of proliferation was measured over time (1–96 h) by DNA accumulation assays (micromoles per µg) and [3H]thymidine incorporation (disintegrations per min). In sc preadipocytes the rate of proliferation was increased between 24–48 h with E2 (10-7 M) in both men (P = 0.028) and women (P = 0.017). Subcutaneous preadipocytes from women were more responsive to E2 in stimulating proliferation than those from men (women vs. men, DNA assay, 24 h, P = 0.014). In omental preadipocytes the increase in the rate of proliferation occurred at 24 h with E2 (10-7 M) in women (P = 0.034) and at 48 h in men (P = 0.031). Gender appeared to influence the rate of proliferation by E2 in omental preadipocytes, with maximal stimulation of proliferation at 48 h in preadipocytes from women treated with E2 (10-7 M; p = 0.007) compared with 72 h in preadipocyte cells from men (P = 0.048), as shown by DNA assay. Both estrone and the androgen DHT had no significant gender- or site-specific effect on the rate of proliferation at any time point. All DNA content data were further validated by thymidine incorporation analysis. In summary, E2 stimulates the rate of proliferation of preadipocytes in a dose-dependent manner, with significant gender- and site-specific differences. Neither estrone nor DHT affected adipocyte mass through proliferation of preadipocytes in this study. In conclusion, E2 may act as an important local factor influencing the proliferation of preadipocytes that may affect fat cell number in a depot- and gender-specific pattern in human abdominal sc and omental adipose tissue.
THE PATTERN OF distribution of fat has important implications with regard to the risk of metabolic diseases, such as type 2 diabetes and the development of cardiovascular disease (1, 2, 3). Accumulation of adipose tissue in the abdominal region (android or central fat), as observed in men, increases the relative risk of these diseases compared with that in women, who tend to accumulate lower body fat in their hips, thighs, and buttocks (gynoid) (3, 4, 5). The distinct pattern of body fat distribution observed in men and women in addition to the changes in fat distribution observed with hyperandrogenic status, such as polycystic ovary syndrome in women and hypogonadism in men, implicate sex steroids as important candidate factors (5, 6). Furthermore, disease characterized by abnormalities in aromatase deficiency or aromatase excess syndrome and in physiopathological situations such as pregnancy, postmenopause, and transsexualism are all associated with alterations in fat distribution (7, 8, 9, 10).
The deposition of adipose tissue in different anatomical regions depends not only on the ability of mature adipocytes to alter their lipid storage capacity, but also on the rate of proliferation of preadipocytes and subsequent differentiation into mature adipocytes (7, 11, 12). As adipocyte number and size are regulated in a coordinated manner, there is strong evidence that an interaction of a number of hormones may be responsible for regulation of fat mass. Previous studies indicate that growth factors, insulin, glucocorticoids, as well as sex steroids hormones enhance preadipocyte proliferation (11, 13, 14, 15, 16). Proliferation is dependent on a close relationship between these factors to increase or decrease each parameter and alter cell-cell interactions (17).
The roles played by sex steroids in the development of adipose
tissue mass in humans through precursor cells proliferating until
confluence and then differentiating into mature adipocytes are not
clearly understood. Previous studies have determined that in human
adipose tissue E2 may increase the rate of proliferation in
vitro, but there are conflicting data on the differentiation of
preadipocytes (10, 15, 16, 18). In addition, E2 may have a
negative effect on the proliferative rate, as previous studies have
shown that the downstream metabolite of E2, 2-methoxyestradiol, can
inhibit proliferation, although it appears to stimulate adipogenesis
(19). The role of E in mediating changes in adipose tissue
mass is also suggested by studies of the ER
knockout mouse. The
ER knockout mouse is lipodystrophic, with loss of visceral adipose
tissue. In human subjects an ER mutation resulting in eunuchoid body
fat distribution has been recorded (19A, 20, 21, 22).
Androgens may also alter adipose tissue mass, but there are few data on their effects on proliferation of preadipocytes. Analysis of the role of androgens in animal studies to date indicates their ability to block both proliferation as well as differentiation, as examined in 3T3-L1 and 3T3-F442A preadipocyte cell lines (23, 24, 25). These effects of androgen on adipose tissue have also been examined in animal castration studies, where castration resulted in an increase in proliferation in both epididymal and perirenal fat. Subsequently, administration of androgens to these cells reversed the effects on proliferation, thereby attenuating the proliferation and restoring the negative effects of androgens (26).
The aim of the present study was to determine the role of sex hormones in human preadipocyte proliferation in both omental and sc fat and in both men and women. For this assessment we addressed the influence of the active and less active forms of E, E2 and estrone (E1), respectively, as well as the influence of DHT in both primary cultured human sc and omental preadipocytes. Secondly, we examined the influence of sex steroid concentration on the rate of proliferation in samples from both men and women to examine gender-specific effects.
Subjects and Methods
Subjects
Subcutaneous and omental abdominal adipose tissues were obtained from 15 female subjects [8 premenopausal women (mean ± SD age, 42.5 ± 5.2 yr; weight, 62.1 ± 7.9 kg) and 7 postmenopausal females (age, 65.2 ± 5.05; weight, 67.1 ± 10.1 kg)] and 14 men (age, 45.7 ± 12.6; weight, 79.8 ± 12.9 kg). All patients were undergoing elective surgery in accordance with guidelines of the South Birmingham ethics committee. Subjects with a history of malignant diseases or diabetes or receiving endocrine therapy (e.g. steroids, hormone replacement, or T4) or antihypertensive therapy were excluded.
Adipose tissue isolation
In brief, 2–5 g wet weight fresh abdominal sc and omental adipose tissues were collected. Tissue was initially washed with 1 x PBS containing penicillin (100 U/ml) and streptomycin (100 µg/ml). Visible blood vessels and connective tissue were removed, as previously described (27). All adipose tissue was digested with the same batch of collagenase class 1 (2 mg/ml; Worthington Biochemical Corp., Freehold, NJ) in 1 x HBSS (Life Technologies, Inc., Paisley, UK) for 1 h at 37 C in a water bath and shaken at 100 cycles/min at 37 C. The disrupted tissue was filtered through a double layered cotton mesh, and preadipocyte cells and adipocytes were separated by centrifugation at 360 x g for 5 min. Adipocytes were then discarded, leaving only the preadipocyte population for culture.
Preadipocyte isolation
Pelleted preadipocyte cells were resuspended for 10 min in erythrocyte lysis buffer (0.154 mol/liter NH4Cl, 10 mmol/liter KHCO3, and 0.1 mmol/liter EDTA) to remove erythrocyte contamination and were centrifuged at 360 x g for 5 min. For assessment of endothelial cell contamination, preadipocyte cells were stained for factor VIII, a known marker of endothelial cells, according to a previously described method (27). Preadipocyte cells were plated in tissue culture dishes in DMEM/nutrient mix F-12 (DMEM/F12; Life Technologies, Inc.) medium supplemented with 15% FBS to enable attachment of preadipocytes (27).
Assessment of proliferation
Two separate assay methods were used to determine the effect of sex steroids on the rate of proliferation in preadipocyte cells: DNA assay and thymidine incorporation. Limited analysis of proliferation data was also performed with a third proliferation assay method, sulforhodamine B.
DNA assay
For determination of DNA accumulation during proliferation, a previously described method was adapted and used (28, 29). Briefly, preadipocytes were incubated in DMEM/F12 and 15% FCS overnight. After this medium was removed, cells were washed and subsequently maintained in DMEM/F12 phenol-red free medium with varying concentrations of 17ß-E2 (10-7–10-9 M), E1 (10-7–10-9 M), and DHT (10-7–10-9 M). Cells were harvested at various time points (1–96 h), and DNA content was measured. At each time point, cells to be harvested were removed from the plate using PBS (0.1% Triton X-100). Samples were maintained on ice, with subsequent analysis of DNA content using a Hoechst 33342 dye (Sigma-Aldrich Corp., Poole, UK). Samples were incubated for 5 min before being assayed. Both standards and samples were read at excitation 356 nM, emission 456 nM wavelengths (luminescence spectrometer LS -5B, Perkin-Elmer Corp., Palo Alto, CA; count time, 60 sec). A standard curve was constructed using calf thymus DNA (Sigma-Aldrich Corp.) from concentrations of 0.025–1.5 µg/µl. Samples were assessed, using the curve constructed, to determine DNA content between control and treatment groups.
Thymidine incorporation
Thymidine incorporation was assessed as detailed by the following method. Isolated preadipocyte cells were resuspended in DMEM/F12 and 15% FCS and plated at a density of 40%. Twenty-four hours postplating the cells, each well containing cells was washed and maintained in DMEM/F12 phenol-red free medium (Life Technologies, Inc.). Treatments were added to each well in triplicate to give final concentrations of E2 (10-7–10-9 M), E1 (10-7–10-9 M), and a nonaromatizable androgen, DHT (10-7–10-9 M). Preadipocytes were cultured alone with DMEM/F-12 phenol red-free medium as a control. At 24-h intervals, medium was replaced with phenol red-free medium containing [3H]thymidine (1.25 µCi; 1 µl/ml medium) and original treatments. Cells were removed for counting at various time points (1–96 h). At each time point, medium was removed, and the cells were incubated with ice-cold trichloroacetic acid (TCA; 6%, wt/vol). After the removal of TCA, each well was incubated for 20 min with NaOH (0.1 M). Finally, cells were removed from the wells and resuspended in scintillation fluid for counting of disintegrations per min (Optiphase HiSafe III, Fisher Chemicals, Leicester, UK). Vials containing scintillant and cells were thoroughly mixed before counting.
Sulforhodamine B assay
In a modified method described by Papazizis and co-workers (30), preadipocytes were assessed for rate of proliferation by sulforhodamine B assay. Preadipocytes were separated as outlined previously and cultured with or without treatments for 6–48 h. At each time point (6, 24, or 48 h), ice-cold TCA (6%) was layered over the preadipocytes, with incubation at 37 C for first hour and at 4 C for the second hour. After this, medium and TCA were removed, and plates were washed with PBS. Subsequently, plates were washed in excess water five times, with plates drying between each wash. Plates were finally blotted and air-dried at room temperature for 30–60 min. Sulforhodamine B [0.4% (wt/vol) in 1% acetic acid] was aliquoted into each well and incubated at 37 C for 1 h, with plates subsequently washed with excess acetic acid (1%). Photographs of the preadipocyte cells were taken at a magnification of x400. Unbuffered Tris base (10 mM) was added to each well, and color was allowed to develop. The absorbencies of the samples were read at 540 nm on a spectrophotometer.
Statistical analysis
Statistical analysis was undertaken using ANOVA for analysis of control vs. treatment groups for either men or women. To compare the significance of different treatments between men and women, unpaired t tests were used. Data are presented as the mean ± SEM.
Results
Effect of E2 on proliferation in sc preadipocytes cells
In preadipocyte cells from women, maximal proliferation occurred
in cells treated with 10-7 M E2
between 24–48 h (48-h DNA assay: control, 12.4 ± 1.3
µmol/µg; 10-7 M E2, 17.5 ±
1.7 µmol/µg; P = 0.028; Fig. 1A
). This was also reflected in the
[3H]thymidine incorporation assays, which
showed a similar finding (48 h [3H]thymidine:
control: 3268.4 ± 294.8 dpm; 10-7
M E2, 5103.1 ± 236.2 dpm; P
= 0.0016; Fig. 2A). Increases in
proliferation were also noted with 10-8 and
10-9 M E2-treated sc
preadipocytes from women, but not to the same extent as that observed
with 10-7 M E2 (Figs. 1A and 2A). Separate analysis of the effect of menopausal status on
proliferation rate with respect to E2 showed no significant
differences.
|
|
),
which was also confirmed by [3H]thymidine
incorporation assays (48-h [3H]thymidine:
control, 3785.3 ± 234.5 dpm; 10-7
M E2, 5036.4 ± 170.2 dpm; P
= 0.0002; Fig. 2B). The administration of 10-8
and 10-9 M E2 to the
preadipocytes from men also increased their rate of proliferation above
the control value for both the 24 and 48 h points. Comparative analysis of the effect of E2 treatment on the rate of proliferation of sc preadipocyte cells between men and women
Examination of DNA content indicated that in both males and
females, E2 (10-7–10-9
M) significantly increased the rate of proliferation over
the 72-h period compared with the control value. The maximal effect of
E2 (10-7 M) on proliferation was
observed at 24 h in sc preadipocytes from women and at 48 h
in sc preadipocytes from men. Direct comparison of the effect of E2
(10-7 M) treatment on the
proliferation rate between these time points determined significant
differences in response to E2 treatment in women compared with men (men
vs. women, DNA assay, 24 h point, P =
0.014; DNA assay, 48 h point, P = 0.038; Fig. 1, A
and B).
In cells treated with lower concentrations of E2
(10-8–10-9
M) an increase in the rate of proliferation, as measured by
DNA content, was observed, but no changes with respect to gender were
found (Fig. 1, A and B). Assessment of the effect of E2 on the rate of
proliferation by measuring [3H]thymidine
content compared with the control value demonstrated a pattern similar
to that observed in DNA content assays (data not shown). It should also
be noted that the rate of proliferation had declined in both male and
female preadipocytes by 72 h, and there were no significant
differences between the rate of proliferation in any treated or
untreated cells after 96 h (data not shown).
Sulforhodamine B assessment of proliferation
The effect of E2 on the rate of proliferation was also measured
qualitatively and quantitatively by a sulforhodamide B assay in both
male and female sc preadipocyte cells. Sulforhodamine B analysis of sc
preadipocytes from women treated with 10-7
M E2 compared with those from men confirmed that the
maximal rate of proliferation occurred around the 24 h point for
women compared with controls (mean ± SEM: 24 h
control, 1.0 ± 0.0; male, 10-7
M E2, 1.63 ± 0.21; female,
10-7 M E2, 1.93 ± 0.43;
P = 0.032), whereas the maximal rate of proliferation
was confirmed to be 48 h for preadipocytes from men.
Sulforhodamine B analysis of preadipocytes from men treated with E2
determined that the maximal rate of proliferation occurred later, at
48 h. To confirm that maximal rates of proliferation at 24 h
were not due to inconsistencies in seeding, rates of proliferation were
assessed at 1 and 6 h by measuring
[3H]thymidine incorporation. The results
indicate that the rate of proliferation between 6 and 24 h
increased due to the mitogenic activity of E2 on preadipocytes (Fig. 2, A and B, and Fig. 3A).
|
In omental preadipocytes from women treated with E2
(10-7 M), maximal proliferation was
induced by 48 h (48-h DNA assay: control, 17.3 ± 2.1
µmol/µg; 10-7 M E2, 28.4 ±
3.3 µmol/µg; P = 0.013). This finding was also
confirmed by [3H]thymidine uptake (48 h:
control, 3073.5 ± 510 dpm; 10-7
M E2, 5057.5 ± 302.0 dpm; P
= 0.010; Fig. 4A). Examination of DNA
content in omental preadipocytes from men treated with
10-7 M E2 indicated that
maximum proliferation occurred at 72 h (72 h: control, 18.5
± 1.4 µmol/µg; 10-7 M
E2, 25.3 ± 1.1 µmol/µg; P = 0.016). This
finding was confirmed by [3H]thymidine
incorporation assay (72 h: control, 2870.0 ± 333.9 dpm;
10-7 M E2, 4542.1 ±
494.8 dpm; P = 0.0084; Fig. 4B).
|
In omental preadipocyte cells from men and women, analysis of DNA
content determined that E2
(10-7–10-9
M) increased the rate of proliferation over the 72-h period
compared with the control value, with a maximal effect on the rate of
proliferation observed with 10-7 M
E2 (Fig. 1C). The maximal effect of E2 (10-7
M) on proliferation was observed at 48 h in omental
preadipocytes from females and at 72 h in omental preadipocytes
from males. Direct comparison of E2 (10-7
M) treatment on the proliferation rate between these time
points determined significant differences in response to the E2
treatments in women compared with men (men vs. women, DNA
assay, 48 h point, P = 0.0007; DNA assay, 72
h point, P = 0.048; Fig. 1, C and D).
Omental preadipocyte cells treated with lower concentrations of E2
(10-8–10-9
M) also increased the rate of proliferation, as measured by
DNA content and [3H]thymidine uptake; however,
no significant differences in the rate of proliferation were observed
between men and women (Fig. 1, C and D; corresponding
[3H]thymidine data not shown).
Menopausal status also did not affect the rate of proliferation when
subgroups were compared.
Effect of E1 on proliferation in sc and omental preadipocyte cells
The effect of E1 on the rate of proliferation was assessed
by both DNA content and [3H]thymidine uptake.
Although both control cells and cells treated with E1
(10-7–10-9
M) proliferated, there was no significant effect of E1 to
enhance proliferation compared with control (Table 1; corresponding
[3H]thymidine data not shown). In addition, no
significant effect was observed between sites or in similarly treated
preadipocytes from men and women. Also, menopausal status did not
significantly affect the rate of proliferation.
|
The rate of proliferation was again assessed by DNA content
and [3H]thymidine incorporation. It was
observed that DHT
(10-7–10-9
M) did not alter the proliferation of preadipocytes
compared with that in controls (Table 2;
[3H]thymidine data not shown). It was also
noted that no significant effect was observed between sites or between
preadipocyte cells from men and women. In addition, changing menopausal
status had no significant effect on the rate of proliferation.
|
The increase in adipose tissue mass observed in both lean and obese individuals is due to a concurrent increase in preadipocyte number and mature adipocyte mass through an increase in the volume of cells (31). This increase in adipose tissue mass is enhanced by numerous growth factors, hormones, and cytokines that influence adipocyte number via an increase in the rate of proliferation in preadipocytes, with an additional effect on subsequent differentiation of the cells into mature, lipid-filled adipocytes. Our study addressed the roles of sex steroids on the rate of proliferation in human cultured preadipocytes. This is the first study to examine the effects of varying concentrations of E2, E1, and DHT on the human preadipocyte proliferative rate in both sexes and in the two major adipose tissue depots.
Using two sensitive methods to measure proliferation we demonstrated that E2 increased the rate of proliferation in preadipocytes, with a maximal effect observed at the highest concentration of E2. Two independent proliferation assay methods were used to evaluate and confirm our results. Although the DNA assay is a more sensitive method for assessment of proliferation, thymidine incorporation data confirmed our initial findings. In addition, confirmation by thymidine incorporation studies demonstrated that E2 affected the rate of proliferation in a gender-and site-specific manner. In sc preadipocyte cells from women, treatment with E2 (10-7 M) induced the maximal rate of proliferation by 24 h, with the resulting rate of proliferation almost double that in the controls (as assessed by [3H]thymidine incorporation). This rate of proliferation was maintained for a further 24 h. In male treated sc preadipocyte cells, however, E2 (10-7 M) had a reduced effect over the same 24-h period. In male preadipocytes treated with E2 the rate of proliferation was stimulated compared with the control value, with an approximate 27% rise compared with an almost 50% increase observed in the female sc preadipocytes. The rate of proliferation of male preadipocytes eventually matched that of female preadipocytes by the 48-h point. Investigation of the effect of E2 on omental preadipocyte cells by both DNA assay and thymidine uptake demonstrated a similar gender-specific pattern on the rate of proliferation E2 (10-7 M) treatment. As shown in the proliferation studies with the sc preadipocytes, omental preadipocyte cells from females were more responsive to E2 than the equivalent male E2-treated omental preadipocyte cells. This heightened response to E2 in women may be due to previous exposure of the cell to E2 in vivo. The omental preadipocyte cells from females treated with E2 maximally proliferated by 48 h, whereas omental preadipocyte cells from males maximally proliferated 24 h later at 72 h.
The effect of E2 on human sc preadipocyte proliferation was first documented by Roncari and colleagues (15), who demonstrated that E2 (10-8 M) stimulated the proliferative rate. The doses used in Roncari’s experiment and in this study were chosen to reflect the high local concentrations of E2 to which preadipocytes are exposed within adipose tissue (32). However, as both preadipocytes and mature adipocytes produce and secrete sex steroids that act in a paracrine and intracrine manner, local concentrations of sex steroids may be greater than circulating levels (32). However, the experiments by Roncari failed to include a study of sc preadipocytes; therefore, the present gender-specific findings were not observed. Our studies largely support Roncari’s early findings. However, as our proliferation data demonstrate, although the rate of proliferation was increased, there was no gender-specific pattern at either 10-8 or 10-9 M E2. Analysis of the effect on proliferation induced by 10-7 M E2 in omental preadipocytes, however, suggested gender-specific effects. These effects may not have been previously observed in the Roncari study, because omental preadipocytes were collected from a relatively small number of subjects (10 in all), whereas this study used a total of 29 preadipocyte samples, with both adipose tissue depots examined. Additionally, the use of FCS in some of the previous studies may have obscured the gender-specific effects (15). Studies investigating the influence of E2 on rat preadipocytes suggested a gender-specific effect of E2. In preadipocytes from female rats, E2 (10-7 M) demonstrated an increase in the rate of proliferation by 50% compared with the control value, whereas treated preadipocytes from male rats failed to be affected by the E2 treatment (16).
E2 demonstrated adipose tissue depot-specific effects in addition to the influence of gender. E2 (10-7 M) treatment stimulated a more rapid rise in proliferation in sc preadipocytes compared with omental preadipocytes for both sexes. It should also be noted that the gender- and depot-specific effects on proliferation were not associated with any changes with adiposity, as there were no significant differences between men or pre- and postmenopausal women.
The relative alteration in proliferation identified between both
the adipose tissue sites and between the sexes may result from gender-
and depot-specific differences at the level of the receptors. Previous
human studies have shown that although women have similar E-binding
capacity in sc and omental adipose tissues, men have a higher E-binding
capacity in sc adipose than in omental adipose tissue
(32). These data suggest a possible mechanism for at least
sc preadipocytes from males proliferating at a higher rate than omental
preadipocytes in response to E2. In addition, the binding study data
and previous ER studies have not determined a gender-specific
differences in receptor number (32, 33). However, it is
important to stress that studies of the effect of regulation of sex
steroids on altering fat distribution may be more revealing than
identifying male and female receptor density alone in vivo
(9, 34, 35). Recent studies by this group have addressed
the role of E2 concentration on ER density and reported that E2 can
differentially regulate both ER and ERß protein expression in a
dose-dependent manner in human sc and omental preadipocytes (36, 37). Although no gender-specific E2 regulation of ER was
addressed, these studies indicate that analysis of both ER and ERß
subtype function are required as well as analysis of both male and
female ER regulation during proliferation in sc and omental
preadipocytes.
Analysis of the effect of E1 on the proliferative rate revealed that although downstream metabolites of E2 such as 2-methoxyestradiol may affect proliferation, as detailed in previous studies, E1 itself had no apparent effect on proliferation (19). Preadipocytes treated with the weakly active E, E1, increased proliferation in a similar manner as in controls, with no effect observed for dose, adipose tissue site, or gender.
DHT had no apparent effect on the proliferative rate compared with that in controls, and the rate of proliferation was unaffected by dose, adipose tissue site, or gender. Although no previous studies in human subjects have examined the role of androgens in preadipocyte proliferation, previous rat studies reported that T, DHT, dehydroepiandrosterone, androstanediol, and androstenediol given at low concentrations (10-7 M) failed to affect preadipocyte proliferation (16). By contrast, other studies show that DHEA induces antimitogenic effects when administered in high micromolar concentrations to 3T3-L1 cells or to preadipocyte cells from rats and pigs (24, 25).
Our study demonstrates that E2 in vitro is able to modulate human preadipocyte proliferation in a gender- and site-specific pattern. Preadipocyte cells from females treated with E2 appear more responsive to a rise in the rate of proliferation than those from men. The present findings also suggest that the weak E, E1, does not influence the proliferative rate, with similar findings observed for DHT. In conclusion, although androgens may alter adipose tissue mass, as shown by in vivo studies, nonaromatizable androgens appear not to alter the proliferative rate as a mechanism in human abdominal preadipocyte cells in vitro (9, 22). This study demonstrates that the local E2 concentration within adipose tissue may represent one potential mechanism for the regulation of regional adipose tissue accumulation in human preadipocytes by altering the rate of proliferation and, hence, number in a gender- and site-specific pattern.
Acknowledgments
We thank all the operative surgeons and theatre staff at both the University Hospitals Trust, the Womens Hospital Trust, and the Priory Hospital Edgbaston who aided in these studies. We also thank Mr. Levick for kindly providing samples (obtained with consent of patients) from his plastic surgery operations at Priory Hospital.
Footnotes
This work was supported by Eli Lilly & Co. and the University of Birmingham studentship scheme.
Abbreviations: DMEM/F12, in DMEM/nutrient mix F-12; E1, estrone; TCA, trichloroacetic acid.
Received April 13, 2001.
Accepted July 11, 2001.
References
2/ß-adrenoreceptor-coupled adenylate cyclase
system and their relationship with adrenergic responsiveness in hamster
fat cells from different anatomical sites. Eur J Biochem 205:867–873[Medline]
2. Endocrinology 141:649–656 and ß in human
adipose tissue and their regulation be 17ß-estradiol [Abstract].
Proc of the 81st Annual Meet of The Endocrine Soc. 3–269
and ß in human
adipose tissue. Diab Obes Metab, in pressThis article has been cited by other articles:
 |
|
 |
|
  E. Dos Santos, M.-N. Dieudonne, M.-C. Leneveu, R. Pecquery, V. Serazin, and Y. Giudicelli In vitro effects of chorionic gonadotropin hormone on human adipose development J. Endocrinol., August 1, 2007; 194(2): 313 - 325. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 J. D. Veldhuis, J. N. Roemmich, E. J. Richmond, and C. Y. Bowers Somatotropic and Gonadotropic Axes Linkages in Infancy, Childhood, and the Puberty-Adult Transition Endocr. Rev., April 1, 2006; 27(2): 101 - 140. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 M. Monjo, E. Pujol, and P. Roca {alpha}2- to {beta}3-Adrenoceptor switch in 3T3-L1 preadipocytes and adipocytes: modulation by testosterone, 17{beta}-estradiol, and progesterone Am J Physiol Endocrinol Metab, July 1, 2005; 289(1): E145 - E150. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 S. R. Daniels, D. K. Arnett, R. H. Eckel, S. S. Gidding, L. L. Hayman, S. Kumanyika, T. N. Robinson, B. J. Scott, S. St. Jeor, and C. L. Williams Overweight in Children and Adolescents: Pathophysiology, Consequences, Prevention, and Treatment Circulation, April 19, 2005; 111(15): 1999 - 2012. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 S. Blanchette, K. Blouin, C. Richard, P. Dupont, V. Luu-The, and A. Tchernof Expression and Activity of 20{alpha}-Hydroxysteroid Dehydrogenase (AKR1C1) in Abdominal Subcutaneous and Omental Adipose Tissue in Women J. Clin. Endocrinol. Metab., January 1, 2005; 90(1): 264 - 270. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
S. Rodriguez-Cuenca, M. Monjo, A. M. Proenza, and P. Roca Depot differences in steroid receptor expression in adipose tissue: possible role of the local steroid milieu Am J Physiol Endocrinol Metab, January 1, 2005; 288(1): E200 - E207. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 P. S. Cooke and A. Naaz Role of Estrogens in Adipocyte Development and Function Experimental Biology and Medicine, December 1, 2004; 229(11): 1127 - 1135. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
L. M. Scavo, M. Karas, M. Murray, and D. Leroith Insulin-Like Growth Factor-I Stimulates Both Cell Growth and Lipogenesis during Differentiation of Human Mesenchymal Stem Cells into Adipocytes J. Clin. Endocrinol. Metab., July 1, 2004; 89(7): 3543 - 3553. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 M. N. Dieudonne, M. C. Leneveu, Y. Giudicelli, and R. Pecquery Evidence for functional estrogen receptors {alpha} and {beta} in human adipose cells: regional specificities and regulation by estrogens Am J Physiol Cell Physiol, March 1, 2004; 286(3): C655 - C661. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 A. Naaz, S. Yellayi, M. A. Zakroczymski, D. Bunick, D. R. Doerge, D. B. Lubahn, W. G. Helferich, and P. S. Cooke The Soy Isoflavone Genistein Decreases Adipose Deposition in Mice Endocrinology, August 1, 2003; 144(8): 3315 - 3320. [Abstract] [Full Text] [PDF]
|
|
| |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
| Endocrinology | Endocrine Reviews | J. Clin. End. & Metab. |
| Molecular Endocrinology | Recent Prog. Horm. Res. | All Endocrine Journals |
) and male (B, 
) sc
preadipocyte cells. Subcutaneous preadipocyte cells were treated with
E2 (10-7 M) measured over time (1–72 h).
Thymidine incorporation is expressed as a measure of disintegrations
per minute (DPM) mean ± SEM. For each graph statistical
analysis compared each control (
) and E2 treatment at the same time
point (1–72 h) by unpaired t test (**, P <
0.01; ***, P < 0.001).
