Calcium Homeostasis During Oral Glucose Load in Healthy Women

D'Erasmo, E; Pisani, Didier F.; Ragno, Alessandro; Raejntroph, N.; Vecci, E; Acca, M

doi:10.1055/s-2007-978731

Cited by 31 publications

(10 citation statements)

References 15 publications

(22 reference statements)

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“…In humans, it was reported that hyperglycemia induced by oral glucose load caused a slight decrease in serum calcium (1.28 to 1.27 mmol/L) and an increase in urinary calcium discharge. Those were in parallel with a decrease in parathyroid hormone level (D'Erasmo et al , 1999). However, the hypocalcemia we observed is much more severe than that described in an earlier report, and the reasons remain elucidated.…”

Section: Discussionmentioning

confidence: 92%

“…As an interesting novel finding, we found that a sustained hypocalcemia accompanies hyperglycemia and acidosis after AMP treatment, and the hypocalcemia may therefore be the reason for the increased seizure rate after stroke. The mechanisms for the hypocalcemia are not clear, although parathyroid hormone suppression is suggested (D'Erasmo et al , 1999). In humans, it was reported that hyperglycemia induced by oral glucose load caused a slight decrease in serum calcium (1.28 to 1.27 mmol/L) and an increase in urinary calcium discharge.…”

Section: Discussionmentioning

confidence: 99%

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When Hypothermia Meets Hypotension and Hyperglycemia: The Diverse Effects of Adenosine 5′-Monophosphate on Cerebral Ischemia in Rats

Zhang

Wang

Luo

et al. 2009

J Cereb Blood Flow Metab

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Mild hypothermia renders potent neuroprotection against acute brain injury. Recent reports show that adenosine 5 0 -monophosphate (AMP) plays a role in thermoregulation and induces hypothermia in mice. Therefore, this study sought to determine whether AMP induces hypothermia in rats and to study its collective effects on cerebral ischemia induced by 2-h middle cerebral artery occlusion. An intraperitoneal injection of AMP induced hypothermia dose-dependently. At the dose of 4 mmol/ kg, AMP induced promising mild hypothermia for 2.5 h. Unexpectedly, the AMP-induced hypothermia failed to reduce infarct volume after brain ischemia; instead, it exaggerated the ischemic damage, indicated by an increased infarct volume, as well as increased incidences of hemorrhagic transformation, seizure, and animal death. Physiologic parameter monitoring revealed that AMP causes profound hypotension, leading to cerebral hypoperfusion. Furthermore, AMP administration resulted in severe hyperglycemia, metabolic acidosis, and hypocalcemia. In addition, western blots showed early dephosphorylation and degradation of AMP-activated kinase in the ischemic cortex in AMP-treated rats. Taken together, our findings suggest that AMP induces hypothermia in rats, probably by limiting cellular access to glucose. However, the potential neuroprotection of AMP-mediated hypothermia against ischemia was overwhelmed by the detrimental effects of hypotension and hyperglycemia, thus making AMP an unlikely agent for inducing hypothermia to protect the brain against ischemic injury.

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Section: Discussionmentioning

confidence: 92%

Section: Discussionmentioning

confidence: 99%

When Hypothermia Meets Hypotension and Hyperglycemia: The Diverse Effects of Adenosine 5′-Monophosphate on Cerebral Ischemia in Rats

Zhang

Wang

Luo

et al. 2009

J Cereb Blood Flow Metab

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“…In eight healthy subjects, rifampicin treatment reduced circulating levels of 25-hydroxyvitamin D and 1␣,25-(OH) 2 D 3 by 34 and 23%, respectively. In addition, rifampicin and phenobarbital are two of the drugs most frequently associated with osteomalacia, a metabolic bone disease characterized by a defect of bone mineralization frequently due to an alteration of vitamin D metabolism (53). This suggests that CAR and/or PXR might be involved in the control of genes involved in vitamin D synthesis or catabolism.…”

Section: Discussionmentioning

confidence: 99%

Expression of CYP3A4, CYP2B6, andCYP2C9 Is Regulated by the Vitamin D Receptor Pathway in Primary Human Hepatocytes

Drocourt¹,

Ourlin

Pascussi

et al. 2002

Journal of Biological Chemistry

330

227

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The fully active dihydroxylated metabolite of vitamin D 3 induces the expression of CYP3A4 and, to a lesser extent, CYP2B6 and CYP2C9 genes in normal differentiated primary human hepatocytes. Electrophoretic mobility shift assays and cotransfection in HepG2 cells using wild-type and mutated oligonucleotides revealed that the vitamin D receptor (VDR) binds and transactivates those xenobiotic-responsive elements (ER6, DR3, and DR4) previously identified in CYP3A4, CYP2B6, and CYP2C9 promoters and shown to be targeted by the pregnane X receptor (PXR) and/or the constitutive androstane receptor (CAR). Full VDR response of various CYP3A4 heterologous/homologous promoter-reporter constructs requires both the proximal ER6 and the distal DR3 motifs, as observed previously with rifampicinactivated PXR. Cotransfection of a CYP3A4 homologous promoter-reporter construct (including distal and proximal PXR-binding motifs) and of PXR or CAR expression vectors in HepG2 cells revealed the ability of these receptors to compete with VDR for transcriptional regulation of CYP3A4. In conclusion, this work suggests that VDR, PXR, and CAR control the basal and inducible expression of several CYP genes through competitive interaction with the same battery of responsive elements.Cytochrome P450 (CYP) 1 enzymes are mainly expressed in the liver and catalyze the metabolic conversion of xenobiotics, including environmental pollutants and drugs, to more polar and easily disposable derivatives (2, 3). CYP genes from the CYP2 and CYP3 families are inducible by many xenobiotics, notably including barbiturates and rifampicin. Two nuclear receptors, the pregnane X receptor (PXR; NR1I2) and the constitutive androstane receptor (CAR; NR1I3), have recently been shown to mediate CYP2 and CYP3 gene induction in animals and man (4 -6). Both PXR and CAR form heterodimers with the retinoid X receptor (RXR; NR2B1). PXR is activated by a wide spectrum of xenobiotics and steroids (4, 7, 8) and controls CYP3A4 and CYP3A7 induction by targeting two specific responsive elements present in the regulatory region of these genes (4, 7-12). The first of these is the proximal PXR-responsive element, located at -160. It consists of an everted repeat of the nuclear receptor half-site AGGTCA separated by 6 nucleotides (ER6); this element is necessary but not sufficient for full transactivation of the CYP3A4 promoter. Indeed, full PXRmediated induction requires the presence of a second distal xenobiotic-responsive element (dPXRE), located between -7800 and Ϫ7200 (9). This element is composite and consists of two direct repeats separated by 3 nucleotides (DR3), encompassing an ER6 motif. In contrast to PXR, CAR is sequestered in the cytoplasm and translocates into the nucleus upon activation, notably in response to phenobarbital (6, 13). Several groups have identified a complex phenobarbital-responsive element module that consists of two nuclear receptor-binding sites (termed NR1 and NR2) and one nuclear factor 1 binding site (12,14). Both NR1 and NR2 are imperfect DR4...

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“…Our own unpublished data showed that this is partially a result of decreases in serum albumin, presumably representing hemodilution related to the osmotic changes that accompany the absorption of a glucose load. However, ionized calcium also decreases, and there is an increase in urinary calcium excretion (60) . These changes are likely to be contributed to by reduced PTH secretion, (60,61) increased circulating concentrations of amylin (which has a calciuric action through the renal calcitonin receptor (62,63) ), and increased calcitonin secretion (64) .…”

Section: Peptides Responsive To Feedingmentioning

confidence: 99%

“…However, ionized calcium also decreases, and there is an increase in urinary calcium excretion (60) . These changes are likely to be contributed to by reduced PTH secretion, (60,61) increased circulating concentrations of amylin (which has a calciuric action through the renal calcitonin receptor (62,63) ), and increased calcitonin secretion (64) . There is also evidence of reduced bone resorption after feeding of fat, protein, or glucose in humans (65–67) .…”

Section: Peptides Responsive To Feedingmentioning

confidence: 99%