Ovariectomy worsens secondary hyperparathyroidism in mature rats during low-Ca diet

Zhang, Yan; Lai, Wallace Wai-Lok; Wu, Chun Fu; Favus, Murray J.; Leung, Ping Chung; Wong, Man Sau

doi:10.1152/ajpendo.00445.2006

Cited by 34 publications

(27 citation statements)

References 46 publications

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“…Our results showed that the increase in serum PTH levels in mature female rats by WF treatment resulted in a significant reduction of urinary Ca excretion without any induction of serum 1,25(OH) 2 D 3 levels or bone resorption. The loss of association between serum PTH and serum 1,25(OH) 2 D 3 levels was also reported in our previous study that the significant increase in PTH levels in mature ovariectomised rats fed LCD did not result in any further increase in serum 1,25(OH) 2 D 3 levels (22) . However, it is of interest to find that the positive actions of WF treatment on Ca balance did not result in any increase in bone mass and bone properties in mature female rats in contrast to our previous reported study on aged female rats (22) .…”

Section: Discussionsupporting

confidence: 85%

Improvement of calcium balance byFructus Ligustri Lucidiextract in mature female rats was associated with the induction of serum parathyroid hormone levels

et al. 2011

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Fructus Ligustri Lucidi (FLL) is a commonly prescribed herb in many kidney-tonifying Traditional Chinese Medicinal formulae for the treatment of osteoporosis. The present study aimed to identify the active fractions in FLL and to characterise its effects on Ca balance, calciotropic hormone levels as well as bone properties in mature female rats fed diets containing different levels of Ca. In the present study, 4-month-old Sprague -Dawley female rats were treated with either FLL ethanol extract (EE), ethyl acetate-soluble fraction of EE (EAF), water-soluble fraction of EE (WF) or their vehicle for 12 weeks on a medium-Ca diet (MCD, 0·6 % Ca, 0·65 % P). Then, the Sprague -Dawley female rats treated with WF or its vehicle for 12 weeks were fed diets containing different levels of dietary Ca (low-Ca diet (LCD), 0·1 % Ca, 0·65 % P; MCD; high-Ca diet (HCD), 1·2 % Ca, 0·65 % P). The results demonstrated that WF from EE but not EAF exerted a prominent effect on Ca balance by inhibiting urinary and faecal Ca excretion. WF significantly increased Ca balance in rats fed MCD or HCD with an associated increase in serum parathyroid hormone (PTH) levels. WF did not alter bone mineral density or bone mineral content of the tibia in all the rats fed with different levels of dietary Ca. In conclusion, WF was responsible for the positive actions of FLL on Ca absorption and balance. The regulation of Ca balance by WF might involve its action in stimulating PTH production in the mature female rats.

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Section: Discussionsupporting

confidence: 85%

Improvement of calcium balance byFructus Ligustri Lucidiextract in mature female rats was associated with the induction of serum parathyroid hormone levels

et al. 2011

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“…32 Another possible factor involved in PTH regulation by estrogens could be calcitriol, but there is no clear evidence to support this hypothesis. Some experimental data suggest that estrogens do not influence calcitriol levels 14,33,34 ; meanwhile, others have shown that estrogens might modulate vitamin D receptor expression 34,35 and decrease serum calcitriol levels. 35,36 In our study, a significant dose-dependent decrease of serum calcitriol and PTH levels was observed with the use of estrogens ( Figures 1A and B and 3A); this decrease was strikingly higher in the case of calcitriol.…”

Section: Discussionmentioning

confidence: 99%

Indirect Regulation of PTH by Estrogens May Require FGF23

Carrillo-López

Román-García

Rodríguez-Rebollar

et al. 2009

Journal of the American Society of Nephrology

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The mechanisms by which estrogens modulate PTH are controversial, including whether or not estrogen receptors (ERs) are present in the parathyroid glands. To explore these mechanisms, we combined a rat model of CKD with ovariectomy and exogenous administration of estrogens. We found that estrogen treatment significantly decreased PTH mRNA and serum levels. We did not observe ER␣ or ER␤ mRNA or protein in the parathyroids, suggesting an indirect action of estrogens on PTH regulation. Estrogen treatment significantly decreased serum 1,25(OH) 2 vitamin D 3 and phosphorus levels. In addition, estrogens significantly increased fibroblast growth factor 23 (FGF23) mRNA and serum levels. In vitro, estrogens led to transcriptional and translational upregulation of FGF23 in osteoblast-like cells in a timeand concentration-dependent manner. These results suggest that estrogens regulate PTH indirectly, possibly through FGF23. 20: 200920: -201720: , 200920: . doi: 10.1681 Estrogen deficiency is the main factor implicated in bone loss in postmenopausal osteoporosis. 1 As a consequence of the lack of estrogens, bone turnover increases, leading to an imbalance between bone formation and bone resorption, favoring the latter. 2,3 This imbalance affects calcium-phosphate metabolism and may increase serum parathyroid hormone (PTH) levels. 4 Estrogen replacement therapy prevents bone loss and fractures, 5,6 acting directly on bone cells through their specific estrogen receptors (ERs): ␣ and ␤. 7,8 In addition, in postmenopausal women, estrogens can also reduce PTH serum levels 4,9 through an as of yet poorly understood mechanism. J Am Soc NephrolA possible direct effect of estrogens reducing PTH acting through ER␣ and ER␤ located in the parathyroid cells has been suggested, but the existence of ER␣ and ER␤ in parathyroid tissue is still a controversial issue. 10 -13 Estrogens may also decrease PTH secretion by acting on other factors such as calcium, 14,15 1,25(OH) 2 D 3 (calcitriol), 15 and phosphorus, 16,17 among others. Recently, fibroblast growth factor 23 (FGF23), involved in phosphorus and vitamin D metabolism, 18 has been suggested to influence PTH synthesis and secretion. 19 In women with chronic kidney disease (CKD), little is known about the role that estrogen deficiency plays in the pathogenesis and progression of bone disease. 20,21 Understanding the mechanism through which estrogens act on PTH is also a subject of interest in these patients, because of the high prevalence of secondary parathyroid disorders. 22 Because several aspects of the effects of estrogens on PTH remain unclear, the objective of this study was to investigate the factors and mechanisms involved in the likely effect of estrogens on the parathyroid gland.

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“…23 Fourth, gastric parietal cells appear to have a potent endocrine role in secreting estrogens. [24][25][26][27] Atrophy of the gastric mucosa, observed in patients infected with CagA-positive Helicobacter pylori, 28 reduces the number of gastric parietal cells and may decrease local production of estrogens. Estrogens produced in the stomach directly induce expression and production of ghrelin, 29,30 which appears to increase bone formation by osteoblasts.…”

Section: Introductionmentioning

confidence: 99%

Use of Acid-Suppressive Drugs and Risk of Fracture: A Meta-analysis of Observational Studies

Eom¹,

Park

Myung

et al. 2011

The Annals of Family Medicine

103

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PURPOSE Previous studies have reported inconsistent fi ndings regarding the association between the use of acid-suppressive drugs such as proton pump inhibitors (PPIs) and histamine 2 receptor antagonists (H 2 RAs) and fracture risk. We investigated this association using meta-analysis. METHODSWe searched MEDLINE (PubMed), EMBASE, and the Cochrane Library from inception through December 2010 using common key words. We included case-control, nested case-control, and cohort studies. Two evaluators independently reviewed and selected articles. We determined pooled effect estimates by using random-effects meta-analysis, because of heterogeneity.RESULTS Of 1,809 articles meeting our initial inclusion criteria, 5 case-control studies, 3 nested case-control studies, and 3 cohort studies were included in the fi nal analyses. The pooled odds ratio (OR) for fracture was 1.29 (95% confi dence interval [CI], 1.18-1.41) with use of PPIs and 1.10 (95% CI, 0.99-1.23) with use of H 2 RAs when compared with nonuse of the respective medications. Long-term use of PPIs increased the risk of any fracture (adjusted OR = 1.30; 95% CI, 1.15-1.48) and hip fracture risk (adjusted OR = 1.34; 95% CI, 1.09-1.66), whereas long-term H 2 RA use was not signifi cantly associated with fracture risk. CONCLUSIONSWe found possible evidence linking PPI use to an increased risk of fracture, but no association between H 2 RA use and fracture risk. Widespread use of PPIs with the potential risk of fracture is of great importance to public health. Clinicians should carefully consider their decision to prescribe PPIs for patients already having an elevated risk of fracture because of age or other factors.

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Ovariectomy worsens secondary hyperparathyroidism in mature rats during low-Ca diet

Cited by 34 publications

References 46 publications

Improvement of calcium balance byFructus Ligustri Lucidiextract in mature female rats was associated with the induction of serum parathyroid hormone levels

Improvement of calcium balance byFructus Ligustri Lucidiextract in mature female rats was associated with the induction of serum parathyroid hormone levels

Indirect Regulation of PTH by Estrogens May Require FGF23

Use of Acid-Suppressive Drugs and Risk of Fracture: A Meta-analysis of Observational Studies

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