Acute effect of estradiol on the renal vitamin D hydroxylases in Japanese quail

Baksi, Samarendra N.; Kenny, Alexander D.

doi:10.1016/0006-2952(78)90187-9

Cited by 29 publications

(16 citation statements)

References 22 publications

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“…However, it was unclear whether the defect recognized represents an altered enzyme response to phosphate depletion alone or is indicative of a generalized regulatory anomaly. Thus, we undertook the work documented in this report to study the modulation of normal and Hyp-mouse renal 1 a-hydroxylase by the other major effector of enzyme activity known in animal species, PTH (27)(28)(29) enhance enzyme activity in Hyp-mice as it does in normal animals, despite a significant reduction of plasma calcium concentration in the mutants (Fig. 1).…”

Section: Resultsmentioning

confidence: 99%

Abnormal parathyroid hormone stimulation of 25-hydroxyvitamin D-1 alpha-hydroxylase activity in the hypophosphatemic mouse. Evidence for a generalized defect of vitamin D metabolism.

Nesbitt¹,

Drezner²,

Lobaugh³

1986

J. Clin. Invest.

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Abnormal regulation of vitamin D metabolism is a feature of Xlinked hypophosphatemic rickets in man and of the murine homologue of the disease in the hypophosphatemic (Hyp)-mouse.We previously reported that mutant mice have abnormally low renal 25-hydroxyvitamin D-la-hydroxylase (la-hydroxylase) activity for the prevailing degree of hypophosphatemia. To further characterize this defect, we examined whether Hyp-mouse renal la-hydroxylase activity responds normally to other stimulatory and inhibitory controls of enzyme function. We studied stimulation by parathyroid hormone (PTH) using: (a) a calciumdeficient (0.02% Ca) diet to raise endogenous PTH; or (b) 24-h continuous infusion of 0.25 IU/h bovine PTH via osmotic minipump. In both cases enzyme activity of identically treated normal mice increased to greater levels than those attained by Hypmice. The relative inability of PTH to stimulate la-hydroxylase activity is not a function of the hypophosphatemia in the Hypmouse since PTH-infused, phosphate-depleted normal mice sustained a level of enzyme activity greater than that of normal and Hyp-mice. In further studies we investigated inhibition of enzyme activity by using: (a) a calcium-loaded (1.2% Ca) diet to suppress endogenous PTH; or (b) 24-h continuous infusion of 0.2 ng/h 1,25-dihydroxyvitamin D3 (1,25(OH)2D3). The la-hydroxylase activity of normal and Hyp-mice was significantly reduced to similar absolute levels following maintenance on the calcium-loaded diet. Further, infusion of 1,25(0H)2D3 caused a comparable reduction of la-hydroxylase activity in normal, Hyp-, and phosphate-depleted normal mice. These observations indicate that the inhibitory control of la-hydroxylase by reduced levels of PTH or increased 1,25(OH)2D3 concentrations is intact in the mutants. However, the inability of PTH and hypophosphatemia to stimulate enzyme activity in a manner analogous to that in normal and phosphate-depleted mice indicates that a generalized defect of la-hydroxylase regulation is manifest in Hyp-mice.

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Section: Resultsmentioning

confidence: 99%

Abnormal parathyroid hormone stimulation of 25-hydroxyvitamin D-1 alpha-hydroxylase activity in the hypophosphatemic mouse. Evidence for a generalized defect of vitamin D metabolism.

Nesbitt¹,

Drezner²,

Lobaugh³

1986

J. Clin. Invest.

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“…Recently we have also reported that estradiol administration in rats increases the tissue content of l,25-(OH)2D3 (Baksi and Kenny, 1978a). Our previous study has shown that estradiol can stimulate 1,25-(OH)2D3 production in Japanese quail within 4 h and that this response occurs prior to the hypercalcemic response of estradiol (Baksi and Kenny, 1978b). A comparable study of the dose-and time-relationship with PTH has not been done to our knowledge.…”

mentioning

confidence: 86%

Acute Effects of Parathyroid Extract on Renal Vitamin D Hydroxylases in Japanese Quail

Baksi¹,

Kenny²

1979

Pharmacology

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The dose- and time-response relationships of parathyroid hormone’s modulation of in vitro 1,25-(OH)₂D₃ and 24,25-(OH)₂D₃ production in Japanese quail were investigated. 4-week-old female Japanese quail were injected intramuscularly with three different doses (30, 90 and 270 USP units/kg) of parathyroid extract (PTH). 4, 12 and 24 h after the in vivo administration of PTH, kidney homogenates were incubated with tritiated 25-(OH)D₃. All three doses of PTH stimulated 1,25-(OH)₂D₃ and inhibited 24,25-(OH)₂D₃ production at 12 h relative to the vehicle-treated control group. The responses of the vitamin D hydroxylases were not detectable at 4 h and had returned to control levels by 24 h. Plasma calcium rose significantly at 4 h with the two higher doses of PTH (90 and 270 USP units/mg) but not with the lowest dose. By 12 h the plasma calcium had returned to control levels except at the highest dose of PTH. By 24 h all of the plasma calcium levels had returned to control values. Plasma inorganic phosphate levels were depressed at 4 h by all three PTH doses; they remained depressed at 12 h and returned to control levels by 24 h. It is concluded that the pharmacological effects of PTH on the renal vitamin D hydroxylases are slower in onset and shorter in duration when compared with those of estradiol.

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“…This increase of 1,25(OH) 2 D is independent of a rise in maternal PTH which remains in the low-normal range in the 1 st trimester 43,[66][67][68][69] . Studies have shown that that CYP27B1 activity can be regulated by other sources including parathyroid hormonerelated protein (PTHrP), oestradiol, prolactin (PRL) and placental lactogen [70][71][72] , all of which are increased in pregnancy and which may help explain the rise in 1,25(OH) 2 D independent of PTH responses. Interestingly, 1,25(OH) 2 D does not readily cross the placenta.…”

Section: Vitamin D and The Regulation Of Mineral Homeostasis During Pmentioning

confidence: 99%

Vitamin D and Human Pregnancy

Grayson¹,

Hewison

2011

Fet. Matern. Med. Rev.

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At the end of 2007, Time magazine listed the “benefits of vitamin D” as one of its top 10 medical breakthroughs for that year. Since then there has been a remarkable upsurge of interest in vitamin D, with new research advances seemingly published on a weekly basis. In particular, there has been increasing awareness of the variability of vitamin D status in populations across the globe and, significantly, a growing debate about the need for revised parameters for vitamin D supplementation. Although sub-optimal vitamin D is likely to be a widespread problem for 21stcentury societies, it is also clear that some groups are at much greater risk of low vitamin D status. Prominent amongst these are pregnant women and the aim of the following review article will be to discuss this problem in further detail with specific emphasis on its potential physiological and clinical impact.

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Acute effect of estradiol on the renal vitamin D hydroxylases in Japanese quail

Cited by 29 publications

References 22 publications

Abnormal parathyroid hormone stimulation of 25-hydroxyvitamin D-1 alpha-hydroxylase activity in the hypophosphatemic mouse. Evidence for a generalized defect of vitamin D metabolism.

Abnormal parathyroid hormone stimulation of 25-hydroxyvitamin D-1 alpha-hydroxylase activity in the hypophosphatemic mouse. Evidence for a generalized defect of vitamin D metabolism.

Acute Effects of Parathyroid Extract on Renal Vitamin D Hydroxylases in Japanese Quail

Vitamin D and Human Pregnancy

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