Local estrogen biosynthesis in males and females.

Simpson, Evan R.; Rubin, Gary; Clyne, Colin; Robertson, Kirsten; O’Donnell, Liza; Davis, Susan Ruth; Jones, Morris

doi:10.1677/erc.0.0060131

Cited by 164 publications

(129 citation statements)

References 42 publications

(27 reference statements)

Supporting

Mentioning

107

Contrasting

Unclassified

Order By: Relevance

“…(17) A second protective mechanism is that the greater amount of adipose tissue available enhances the ability to produce endogenous estrogens, which preserve BMD. (18) Third, women who carry more fat mass may benefit from cushioning of their hip by gluteofemoral adipose tissue, which reduces impact forces when they fall and hence their chance of fracture. (19) A protective association of physical activity, often measured as leisure time activity in older studies, with hip fracture has been reported previously.…”

Section: Discussionmentioning

confidence: 99%

“…(16) This protective effect has been attributed to higher levels of BMD resulting from increased chronic strain on the bones, an increased production of estrogens from larger stores of adipose tissue, and/or a reduced impact from falls because of a greater cushioning by subcutaneous adipose tissue. (17)(18)(19) Since body mass index (BMI) may be part of the causal pathway for the effect of physical activity on hip fracture risk, and because active people tend to have a lower body weight than inactive people, (9,20) the independent effects of BMI and physical activity on hip fracture risk need clarification.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Body mass index and physical activity in relation to the incidence of hip fracture in postmenopausal women

Armstrong

Spencer

Cairns

et al. 2010

Journal of Bone and Mineral Research

107

View full text Add to dashboard Cite

Hip fracture risk is known to increase with physical inactivity and decrease with obesity, but there is little information on their combined effects. We report on the separate and combined effects of body mass index (BMI) and physical activity on hospital admissions for hip fracture among postmenopausal women in a large prospective UK study. Baseline information on body size, physical activity, and other relevant factors was collected in 1996-2001, and participants were followed for incident hip fractures by record linkage to National Health Service (NHS) hospital admission data. Cox regression was used to calculate adjusted relative risks of hip fracture. Among 925,345 postmenopausal women followed for an average of 6.2 years, 2582 were admitted to hospital with an incident hip fracture. Hip fracture risk increased with decreasing BMI: Compared with obese women (BMI of 30þ kg/m 2 ), relative risks were 1.71 [95% confidence interval (CI) 1.47-1.97)] for BMI of 25.0 to 29.9 kg/m 2 and 2.55 (95% CI 2.22-2.94) for BMI of 20.0 to 24.9 kg/m 2 . The increase in fracture risk per unit decrease in BMI was significantly greater among lean women than among overweight women ( p < .001). For women in every category of BMI, physical inactivity was associated with an increased risk of hip fracture. There was no significant interaction between the relative effects of BMI and physical activity. For women who reported that they took any exercise versus no exercise, the adjusted relative risk of hip fracture was 0.68 (95% CI 0.62-0.75), with similar results for strenuous exercise. In this large cohort of postmenopausal women, BMI and physical activity had independent effects on hip fracture risk. ß

show abstract

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Body mass index and physical activity in relation to the incidence of hip fracture in postmenopausal women

Armstrong

Spencer

Cairns

et al. 2010

Journal of Bone and Mineral Research

107

View full text Add to dashboard Cite

show abstract

“…Although estrogen has a well-established effect on the skeleton [23], our findings showed greater bone mass and lower bone turnover in HRT(+) compared with HRT(−) subjects for the normal-weight group, but not the obese group. This indicates that women of lower body weights may be more responsive to HRT compared with obese subjects, whose higher body fat content may be a significant endogenous source of estrogen [24], and whose higher weight-bearing (compared with normal-weight women) is expected to independently promote higher bone mass. Nevertheless, once women with higher endogenous sources of estrogen (i.e., as in obesity) take HRT, these endogenous sources are less likely to be important.…”

Section: Discussionmentioning

confidence: 99%

Bone turnover and body weight relationships differ in normal-weight compared with heavier postmenopausal women

et al. 2003

View full text Add to dashboard Cite

Low body weight is associated with increased risk for fractures, whereas higher body weight has been shown to be protective against osteoporosis. This study evaluated whether body weight plays a role regulating bone turnover and mass in normal-weight (body mass index (BMI) <25 kg/m 2 ), overweight (BMI 25-29.9 kg/ m 2 ) and obese (BMI ≥ 30 kg/m 2 ) postmenopausal women who were either receiving hormone replacement therapy [HRT(+)] or not [HRT(−)] (total of six groups). Body weight, BMI, total body bone mineral content (TBBMC), and markers of bone formation (serum osteocalcin) and bone resorption (urinary pyridinoline (PYD) and deoxypyridinoline) were retrospectively analyzed in 210 postmenopausal women. The mean age was 67±6 years, with mean body weight of 70.8±14.2 kg, ranging from 45.0 to 115.5 kg. Body weight was positively correlated with TBBMC (r=0.50, p<0.0001). There was a lower TBBMC and higher bone formation rate in normal-weight than obese HRT(−) women, but in women taking HRT there were no differences between BMI categories. In addition, in normal-weight HRT(−) women only, PYD and body weight showed a negative correlation (r=−0.39, p=0.01). Among normal-weight, but not overweight or obese subjects, we observed higher TBBMC and lower bone turnover in the HRT(+) compared with the HRT(−) group. Regression models explained 36% of the variance in TBBMC, mainly through body weight. Additional models could only explain 11-15% of the variance in bone turnover. Taken together, these data suggest that among normal-weight but not obese postmenopausal women, higher bone turnover is associated with lower bone mass, and that only normal-weight women show a different bone turnover profile with HRT treatment. Body weight should be considered an important factor in bone metabolism with relevant clinical implications.

show abstract

“…A greater body weight may prevent the decrease in E 2 due to local synthesis of estrogen in adipose tissue (28) and may protect against bone loss. In addition, the decreases in E 2 during weight reduction tended to be associ-ated with decreases in calcium absorption in lean rats.…”

Section: Discussionmentioning

confidence: 99%

Energy Restriction Reduces Fractional Calcium Absorption in Mature Obese and Lean Rats

Cifuentes

Morano

Chowdhury

et al. 2002

The Journal of Nutrition

View full text Add to dashboard Cite

Weight loss is associated with bone loss and the risk may be greater in lean than heavier individuals, but the mechanisms involved remain unclear. We hypothesized that energy restriction (EnR) would decrease true fractional Ca absorption (TFCA) and be mediated by Ca-regulating hormones, but differently in obese and lean rats. Rats were fed a high fat (47% energy) or low fat (16% energy) diet for 4 mo. At 6 mo of age, the resulting lean [284 ± 28g (mean ± SD, n = 18)] and obese (319 ± 34g, n = 20) groups (P < 0.005) were divided into controls (CTL, ad libitum) and energy-restricted (40% restriction) groups. At baseline, bone resorption (urinary crosslinks) was higher and bone formation (serum osteocalcin) was lower in obese than in lean rats, whereas Ca balance components and Ca-regulating hormones did not differ. EnR for 10 wk reduced body weight by 25 ± 7% compared with a 6 ± 6% gain in CTL rats (P < 0.001). For both lean and obese rats, TFCA (5-d measurement, 45 Ca radioisotope) decreased from 30 ± 9% to 24 ± 9% with EnR, compared with 25 ± 10% to 29 ± 11% in controls (P < 0.05). Weight loss was directly correlated with the decrease in TFCA (r = 0.34, P < 0.05). Uterine weights indicated a reduced estrogenic activity in energy-restricted rats (P < 0.0001). In lean, but not obese rats, serum estradiol (E 2 ) correlated with weight loss (r = 0.52, P < 0.05), and tended to correlate with the decrease in TFCA (r = 0.48, P = 0.06). At the end of the study, serum 25-hydroxyvitamin-D was lower and urinary Ca was higher in lean than obese energy-restricted rats. Distinct endocrine profiles during weight loss in obese and lean rats suggest that the susceptibility of bone and Ca metabolism to EnR could differ depending on initial body weight.

show abstract

Local estrogen biosynthesis in males and females.

Cited by 164 publications

References 42 publications

Body mass index and physical activity in relation to the incidence of hip fracture in postmenopausal women

Body mass index and physical activity in relation to the incidence of hip fracture in postmenopausal women

Bone turnover and body weight relationships differ in normal-weight compared with heavier postmenopausal women

Energy Restriction Reduces Fractional Calcium Absorption in Mature Obese and Lean Rats

Contact Info

Product

Resources

About