Modulation of serum parathyroid hormone and ionized calcium concentrations during reproduction in rats fed a low calcium diet

To study the effects of chronic metabolic acidosis on the metabolism of 1,25-dihydroxyvitamin D3 [1,25(OH)2D3] rats were given either a low calcium diet (LCD) (0.002% calcium) or chow (1.2% calcium); ammonium chloride (NH4Cl) was added (1 or 1.5%) to the drinking water of some rats eating LCD or chow while others served as nonacidotic controls. LCD increased circulating 1,25(OH)2D3 levels from 46 +/- 14 to 204 +/- 24 pg/ml (P less than 0.001) in the absence of NH4Cl; 1.5% NH4Cl prevented the increase in 1,25(OH)2D3 (25 +/- 6 vs. 27 +/- 8 pg/ml (P, NS) but 1% NH4Cl did not (50 +/- 12 vs. 161 +/- 23 pg/ml; P less than 0.001). Acidosis suppressed neither serum immunoreactive parathyroid hormone (PTH) nor urine cAMP response to LCD. Although total serum calcium and phosphorus showed no regular changes with NH4Cl, acidosis raised blood ionized calcium in rats fed either chow or LCD, and serum 1,25(OH)2D3 levels were inversely correlated with ionized calcium (r = 0.714; P less than 0.001) during LCD. Chronic NH4Cl acidosis prevented serum 1,25(OH)2D3 from rising during LCD, independent of changes in PTH secretion, cAMP generation, or serum phosphorus. The absence of a 1,25(OH)2D3 response may be due to increased ionized calcium produced by acidosis.

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Different Dietary Calcium Intake and Relative Supersaturation of Calcium Oxalate in the Urine of Patients Forming Renal Stones

Clinical Science ◽

10.1042/cs0930257 ◽

1997 ◽

Vol 93 (3) ◽

pp. 257-263 ◽

Cited By ~ 21

Author(s):

Piergiorgio Messa ◽

Martino Marangella ◽

Luisa Paganin ◽

Mara Codardini ◽

Aldo Cruciatti ◽

...

Keyword(s):

Parathyroid Hormone ◽

Calcium Oxalate ◽

Calcium Absorption ◽

Dietary Calcium ◽

Calcium Excretion ◽

Soluble Complex ◽

Complex Species ◽

Calcium Diet ◽

Low Calcium Diet ◽

Low Calcium

1. Dietary calcium restriction, an efficient practice in reducing urinary calcium excretion, has been reported to induce either an increase or no change in oxalate excretion, questioning its use in hypercalciuric stone-forming patients. In addition, calcium restriction has been previously demonstrated to induce other urinary changes which might influence the relative supersaturation of calcium oxalate. So the overall effect of calcium deprivation on the relative supersaturation of calcium oxalate is unpredictable. 2. The aim of the study was to evaluate the effect of dietary calcium restriction on the relative supersaturation of calcium oxalate in the urine of stone-forming patients utilizing a computer methodology which takes into account the main soluble complex species of oxalate. 3. We studied 34 stone-forming patients on both a free-choice diet, whose Ca and oxalate content (24 and 1.2 mmol respectively) was assessed by dietary inquiry, and after 30 days on a prescribed low-calcium and normal oxalate diet (11 and 1.1 mmol respectively). Under both conditions, the excretion of the main urinary parameters related to dietary composition, electrolytes, oxalate and daily citrate urinary excretion, were measured. The relative supersaturation of calcium oxalate was calculated by means of an iterative computer method which takes into account the main soluble complex species on which the solubility of calcium oxalate is dependent. In addition, intact parathyroid hormone and 1,25-dihydroxyvitamin D blood levels were also evaluated. In 13 of the patients intestinal calcium absorption was evaluated during both a free- and a low-calcium diet, utilizing kinetics methodology. 4. The low-calcium diet induced, together with an expected reduction of calcium excretion, a marked increase in oxalate urinary output. This finding was independent of the presence or otherwise of hypercalciuria and of the serum levels of parathyroid hormone and vitamin D. Intestinal calcium absorption was also stimulated by calcium deprivation and its levels were well correlated with oxalate excretion. Minor changes in magnesium and citrate excretion were also observed. The overall effect on the relative supersaturation of calcium oxalate consisted in a substantial increase in this parameter during the low-calcium diet. 5. In conclusion, our data reinforce the concept that dietary calcium restriction has potentially deleterious effects on lithogenesis, by increasing the relative supersaturation of calcium oxalate.

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Plasma calcitonin and parathyroid hormone levels in growing pigs on different diets. II. Low calcium diet

annales de biologie animale biochimie biophysique ◽

10.1051/rnd:19790510 ◽

1979 ◽

Vol 19 (3A) ◽

pp. 647-659

Author(s):

A. POINTILLART ◽

J. M. GAREL ◽

L. GUÉGUEN ◽

Colette COLIN

Keyword(s):

Parathyroid Hormone ◽

Growing Pigs ◽

Hormone Levels ◽

Calcium Diet ◽

Low Calcium Diet ◽

Low Calcium

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Icariin protects against cage layer osteoporosis by intervening in steroid biosynthesis and glycerophospholipid metabolism

Animal Diseases ◽

10.1186/s44149-021-00001-z ◽

2021 ◽

Vol 1 (1) ◽

Author(s):

Zhengwang Yu ◽

Jie Huang ◽

Zhongxin Zhou

Keyword(s):

Metabolic Diseases ◽

Chinese Herb ◽

Therapeutic Effects ◽

Mineral Density ◽

Steroid Biosynthesis ◽

Metabolic Pathway Analysis ◽

Effective Prevention ◽

Calcium Diet ◽

Low Calcium Diet ◽

Low Calcium

AbstractCage layer osteoporosis (CLO) is a common bone metabolism disease in the breeding industry of China. However, effective prevention for CLO has not been developed. Icariin (ICA), the main bioactive component of the Chinese herb Epimedium, has been shown to have good therapeutic effects on bone-related diseases. In this study, the effects of ICA were further evaluated in a low-calcium diet-induced CLO, and a serum metabolomics assay was performed to understand the underlying mechanisms. A total of 144 31-wk-old Lohmann pink-shell laying hens were randomly allocated to 4 groups with 6 replicates of 6 hens per replicate. The 4 dietary treatment groups consisted of a basal diet (3.5% calcium), a low-calcium diet (2.0% calcium), and a low-calcium diet supplemented with 0.5 or 2.0 g/kg ICA. The results showed that ICA exerted good osteoprotective effects on low-calcium diet-induced CLO. ICA significantly increased femur bone mineral density, improved bone microstructure, decreased bone metabolic level, and upregulated mRNA expression of bone formation genes in femoral bone tissue. Serum untargeted metabolomics analysis showed that 8 metabolite levels were significantly changed after ICA treatment, including increased contents of 7-dehydrocholesterol, 7-oxocholesterol, desmosterol, PC (18:1(9Z)/18:1(9Z)), PS (18:0/18:1(9Z)), N,N-dimethylaniline and 2-hydroxy-butanoic acid and decreased N2,N2-dimethylguanosine. Metabolic pathway analysis based on the above 8 metabolites indicated that ICA mainly perturbed steroid biosynthesis and glycerophospholipid metabolism. These findings suggest that ICA can effectively prevent bone loss in low-calcium diet-induced CLO by mediating steroid biosynthesis and glycerophospholipid metabolism and provide new information for the regulation of bone metabolic diseases.

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