Calcium metabolism in glucocorticoid-treated pony foals.
Abstract: Pony foals were injected intramuscularly with 0, 0.5, or 5.0 mg dexamethasone per 100 kg body weight daily for up to 11 months. True absorption of dietary calcium was inhibited by treatment at 18 days (57% versus 14% of intake; P less than .01) and 10 months (72% versus 55% versus 43%: P less than .01), but not at 2 or 7 months, and was independent of age and treatment related decreases in intestinal calcium binding protein activities. Uninary excretion of calcium was increased by treatment through 7 months but decreased at 10 months. Treatment for 18 days resulted in total calcium excretions equivalent to 127% of dietary intake. All animals were in positive calcium balance thereafter. Endogenous fecal calcium excretion was not affected by treatment, age, or sex, averaging 18.0 mg per kg body weight per day. At 2 months, rates of calcium deposition into bone were 13.02, 7.01 and 6.83 g per 100 kg per day in ponies treated with 0, 0.5 and 5.0 mg per 100 kg, respectively. Corresponding rates of calcium removal from bone were 5.41, 1.88, and 2.69 g per 100 kg per day. These rates remained significantly inhibited in the treated ponies at 7 and 10 months. The net effect of dexamethasone treatment was an inhibition of bone turnover: calcium removal was suppressed more than inhibition of bone turnover: calcium removal was suppressed more than calcium deposition.
Publication Date: 1982-01-01 PubMed ID: 7054471DOI: 10.1093/jn/112.1.77Google Scholar: Lookup
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- Journal Article
Summary
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The research focused on examining the effects of glucocorticoid treatment on the calcium metabolism of pony foals. It was found that this treatment led to reduced absorption of dietary calcium, increased urinary excretion of calcium, and an overall inhibition of bone turnover.
Overview of the Research Methodology
- Pony foals were given daily intramuscular injections of dexamethasone (a type of glucocorticoid) at dosages of 0, 0.5, or 5.0 mg per 100 kg of body weight for a period of up to 11 months.
- The true absorption of dietary calcium was measured at 18 days and 10 months into the treatment, as well as at 2 and 7 months, which showed no inhibition.
- The urinary excretion of calcium was monitored throughout the treatment period.
- Lastly, the researchers measured the rates of calcium deposition into and removal from the bone at 2 months, which then remained significantly inhibited in the treated ponies at 7 and 10 months.
Key Findings
- The absorption of dietary calcium was found to be inhibited by the dexamethasone treatment at 18 days and 10 months, but not at 2 or 7 months.
- The treatment led to an increase in urinary excretion of calcium through 7 months, but a decrease was noticed at 10 months.
- After 18 days of treatment, total calcium excretions were equivalent to 127% of dietary intake, indicating a severe disruption to calcium absorption.
- Despite these disruptions, all animals had a positive calcium balance after the 18 days of treatment, indicating body’s ability to compensate and maintain overall calcium homeostasis.
- There was no impact by the treatment on endogenous fecal calcium excretion, which averaged 18.0 mg per kg body weight per day regardless of age or sex.
- Rates of calcium deposition into bone were significantly inhibited for treated ponies compared to untreated ones. Similarly, the rates of calcium removal from bone were also suppressed in treated ponies.
Conclusions
- The glucocorticoid treatment by dexamethasone led to disruption in calcium metabolism in pony foals, particularly in the absorption and excretion of calcium, as well as the bone turnover process.
- Despite varied absorption and excretion rates at different times, all ponies maintained a positive calcium balance eventually, hinting towards the adaptive mechanisms of the body.
- The net effect of dexamethasone treatment was an inhibition of bone turnover, with suppression of calcium removal being more significant than inhibition of calcium deposition.
- This study provides insights into the impacts of gluococorticoid treatments on calcium metabolism, which could be critical in the management of equine health and disease conditions related to calcium metabolism and bone health.
Cite This Article
APA
Glade MJ, Krook L, Schryver HF, Hintz HF.
(1982).
Calcium metabolism in glucocorticoid-treated pony foals.
J Nutr, 112(1), 77-86.
https://doi.org/10.1093/jn/112.1.77 Publication
Researcher Affiliations
MeSH Terms
- Absorption
- Animals
- Calcium / blood
- Calcium / metabolism
- Calcium-Binding Proteins / metabolism
- Dexamethasone / pharmacology
- Feces
- Horses / metabolism
- Kinetics
- Time Factors
- Tissue Distribution
Citations
This article has been cited 2 times.- Mainguy-Seers S, Lavoie JP. Glucocorticoid treatment in horses with asthma: A narrative review. J Vet Intern Med 2021 Jul;35(4):2045-2057.
- Mainguy-Seers S, Picotte K, Lavoie JP. Efficacy of tamoxifen for the treatment of severe equine asthma. J Vet Intern Med 2018 Sep;32(5):1748-1753.
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