Anticonvulsive profile of two GABAB receptor antagonists on acute seizure mice models.

INTRODUCTION: DL-3-hydroxy-3-phenylpentanamide (HEPP) and DL-3-hydroxy-3-(4'chlorophenyl)-pentanamide (Cl-HEPP) are phenyl-alcohol-amides that are metabotropic GABAB receptor (MGBR) antagonists and protective against absence seizures. This study aims to further characterize the anticonvulsant profile of these drugs. METHODS: HEPP and Cl-HEPP were evaluated in various standardized acute seizure and toxic tests in female Swiss-OF1 mice. RESULTS: Toxicities of HEPP and Cl-HEPP were limited; doses up to 30 mg/kg did not result in hypothermia, reduced spontaneous locomotor activity, or failure of the rotarod test, with doses >15 mg/kg potentiating pentobarbital-induced sleep. In maximal electroshock-induced seizures, 20 mg/kg Cl-HEPP protected 100 % of mice; lower doses shortened post-ictal recovery. Seizure protection occurred against subcutaneous pentylenetetrazole and picrotoxin, being limited against N-methyl-d-aspartate. In bicuculline test, clonic or fatal tonic seizures were decreased, onset delayed, and recovery improved; ED50 values (dose protecting 50 % of the animals) were 37.5 and 25 mg/kg for HEPP and Cl-HEPP, respectively. In magnesium deficiency-dependent audiogenic seizures (MDDAS), ED50 values were 3 and 8 mg/kg for Cl-HEPP and HEPP, respectively. The components of MDDAS (latency, wild running, seizure, and recovery phases) in unprotected animals were only minimally affected by near ED50 doses of Cl-HEPP and HEPP. DISCUSSION: HEPP and, to a greater extent, Cl-HEPP provide anti-seizure protections in several acute seizure tests in mice at nontoxic doses. These results are consistent with the action of these drugs on diverse molecular targets directly resulting from their MGBR antagonistic properties. However, other mechanisms might occur possibly for the protection given in the MES test. Finally, a similarity in the modulation of MDDAS components between the two phenyl alcohol amides and ethosuximide could also be based on the MGBR antagonistic properties of the former, given the recently re-evaluated therapeutic relevant targets of the latter.

Brain anticonvulsant protection of mice given chronic carbamazepine under various fatty acid and magnesium diet conditions.

The anticonvulsant and mood stabilizer drug carbamazepine (CBZ) was evaluated for anti-seizure activity after drug pretreatment of young weaning mice given various oil-based diets. These diets had various mono-(MUFA) and poly-(PUFA) unsaturated fatty acid contents, were associated or not with magnesium deprivation, and were given over the entire experimental period (34 days). The diets included a commercial and three purified synthetic diets (n-6 PUFA, n-3 PUFA and MUFA-based chows containing 5% corn/sunflower oils 1:3, 5% rapeseed oil and 5% high oleic acid sunflower oil/sunflower oil 7:3, respectively). A 10-days CBZ treatment (50 mg/kg/day fragmented in two daily intraperitoneal injections of 25 mg/kg) was given 20 days after initiating diet administration and evaluations of mice was performed 4 days after arrest of CBZ in various seizure tests. In these conditions, CBZ pretreatment still exhibited anticonvulsant protection especially in magnesium-deficient animals. Ethosuximide (ESM)-like profiles under MUFA and n-3 PUFA diets and unusual GABA(A)ergic profile under n-6 PUFA diet in magnesium-deficiency dependent audiogenic seizures (MDDAS) test as well as protection against NMDA-induced seizures in all lipid (n-3 PUFA>MUFA and n-6 PUFA) diet conditions were observed in CBZ-pretreated mice. By highlighting ESM-like and anti-NMDA mechanisms previously induced by an n-3 PUFA diet, present CBZ anticonvulsant properties suggest brain protective targets common to CBZ and n-3 PUFAs.

Magnesium-deficiency does not alter calcineurin inhibitors activity in mice.

INTRODUCTION: Tacrolimus (TAC) and cyclosporin (CsA) are commonly responsible for hypomagnesemia that predisposes in turn for hypertension, renal impairment and encephalopathy. OBJECTIVE: The effects of TAC on Mg(2+)-homeostasis and of pre-existing Mg(2+)-deficiency on TAC immunosuppressive activity were compared to CsA in mice. METHODS: Mg(2+) was quantified in plasma, erythrocytes, urine, feces, and femurs from mice treated with TAC 5mg/kg/day. Immunosuppression was assessed in splenocytes by mixed lymphocyte reaction, IL-2 quantification and CN activity determination. RESULTS: Plasma and urine Mg(2+) levels in TAC-treated mice were significantly lower from day 7 until day 21 (p<0.05 versus control) and returned to control value at day 28. Mg(2+) levels were unchanged in erythrocyte, feces and femur. Inhibition of allogeneic proliferation, IL-2 production and CN activity were 68, 56 and 30% lower (p<0.01) after 7 days of TAC-treatment, and 72, 68 and 51% lower (p<0.01) after 7 days of CsA-treatment with a dose of 50mg/kg/day. Dietary-induced hypomagnesemia resulted in significant inhibition of CN activity (p<0.01) without alteration of IL-2 production or allogeneic proliferation. However, it did not alter the effects observed with CsA- or TAC-treatment on allogeneic proliferation, IL-2 production and CN activity. CONCLUSION: By contrast with CsA, long-course TAC-treatment induced an early, but transient, and moderate hypomagnesemia without alteration of bone or erythrocyte stocks, intestinal absorption or renal function. Therefore, in clinical use, TAC should be preferred to CsA in patients with pathological or pharmacological conditions which favor Mg(2+)-deficiency. However, dietary-induced hypomagnesemia did not alter the immunosuppressive effects of TAC and CsA.

Brain protection by rapeseed oil in magnesium-deficient mice.

Diets given for 30 days with various mono-(MUFA) and poly-(PUFA) unsaturated fatty acid contents were evaluated for brain protection in magnesium-deficient mice: a commercial and three synthetic diets (n-6PUFA, n-3PUFA and MUFA-based chows enriched with 5% corn/sunflower oils 1:3, with 5% rapeseed oil and with 5% high oleic acid sunflower oil/sunflower oil 7:3, respectively). Unlike magnesium deprivation, they induced significant differences in brain and erythrocyte membrane phospholipid fatty acid compositions. n-3PUFA but not other diets protected magnesium-deficient mice against hyperactivity and moderately towards maximal electroshock- and NMDA-induced seizures. This diet also inhibited audiogenic seizures by 50%, preventing animal deaths. Because, like n-6PUFA diet, matched control MUFA diet failed to induce brain protections, alpha-linolenate (ALA) rather than reduced n-6 PUFA diet content is concluded to cause n-3PUFA neuroprotection. Present in vivo data also corroborate literature in vitro inhibition of T type calcium channels by n-3 PUFA, adding basis to ALA supplementation in human anti-epileptic/neuroprotective strategies.

Activities of α-asarone in various animal seizure models and in biochemical assays might be essentially accounted for by antioxidant properties.

Anticonvulsant properties of α-asarone were studied in mice at three doses with different toxicity. The 100mg/kg dose decreased both treadmill performance and locomotor activity, caused hypothermia, and potentiated pentobarbital-induced sleep. The last two effects and no toxicity were observed at 60 and 22mg/kg, respectively. In chemical (pentylenetetrazole, picrotoxin, N-methyl-D-aspartate, pilocarpine) and electrical (maximal electroshock) seizure tests, neither seizures nor death were prevented by 60 mg/kg α-asarone which, however, exhibited protective-like effects (delay in the onset of clonic and/or tonic seizures and/or in the death of mice). Magnesium deficiency-dependent audiogenic seizures responded to non-toxic doses of α-asarone (60 mg/kg and less): 22 mg/kg protecting 50% of tested animals. Because these seizures respond to both anti-seizure and antioxidant compounds, antioxidant properties of α-asarone were studied, indicating 5 Units of superoxide dismutase-like activity per mg α-asarone. Treatment of mice by α-asarone (daily dose of 100mg/kg during 7 days) induced brain antioxidant enzymes (superoxide dismutase, glutathione peroxidase and reductase) in striatum and hippocampus and to a lesser extent in cortex. In view of recent findings about deleterious roles of chronic inflammatory/oxidant stresses in human epilepsy outcome, antioxidant and inductive properties of α-asarone are proposed to be coherent bases for traditional clinical efficacy.

1,2-ethane bis-1-amino-4-benzamidine is active against several brain insult and seizure challenges through anti-NMDA mechanisms targeting the 3H-TCP binding site and antioxidant action.

Five bis-benzamidines were screened towards murine magnesium deficiency-dependent audiogenic seizures, unravelling two compounds with efficacious doses 50 (ED(50)) less than 10mg/kg. They were also screened against maximal electroshock and subcutaneous pentylenetetrazole-induced seizures, and explored for superoxide -scavenging activity. 1,2-Ethane bis-1-amino-4-benzamidine (EBAB) was selected and evaluated in 6 Hz seizure test (ED(50)=49 mg/kg) and at 4 microg/kg in focal cerebral ibotenate poisoning in pups (sizes of both white and grey matter wounds were halved). EBAB was further tested on NMDA-induced seizures in mice (ED(50)=6 mg/kg) and on (3)H-TC -binding to a rodent cerebral preparation (IC(50)=1.4 microM). Taken as a whole, present data emphasise the suitability of bis-benzamidines as templates for designing brain protective compounds.

Experimental stroke protection induced by 4-hydroxybenzyl alcohol is cancelled by bacitracin.

Induction of protein disulfide isomerase (PDI) is validated as a main mechanism by which 4-hydroxybenzyl alcohol (4-HBA), an active principle of Gastrodia elata Blume, reduces cerebral infarct volumes in a murine model of focal brain ischemia/reperfusion. In contrast to its position isomers, i.e. 3-hydroxybenzyl alcohol (3-HBA) and 2-hydroxybenzyl alcohol (2-HBA), and to aliphatic diols (1,4-butanediol and 1,5-pentanediol), 4-HBA administered intravenously at 25 mg/kg protected mice, significantly reducing total, cortical and sub-cortical infarct volumes by 42, 28 and 55%, respectively. All compounds, 4-HBA included, were devoid of antioedematous properties. Only the stroke protective 4-HBA, but neither 3-HBA nor 2-HBA, was capable of significantly inducing PDI in intact mouse brains. Stroke protection was fully prevented by bacitracin (500 mg/kg), a known inhibitor of PDI, which, without affecting basal brain PDI levels, altered the ability of 4-HBA to induce significantly PDI in intact brains. Taken as a whole, our data indicate that stroke protection induced by 4-HBA involves PDI as a key player, making this protein a valuable target to control brain injury disorders. The fact that 4-HBA, at doses up to 200mg/kg, was devoid of neurotoxicity in the rotarod test is also a decisive element to promote the neuroprotective use of this plant compound.

Threshold to N-methyl-D-aspartate-induced seizures in mice undergoing chronic nutritional magnesium deprivation is lowered in a way partly responsive to acute magnesium and antioxidant administrations.

Magnesium deficiency may be induced by a diet impoverished in magnesium. This nutritional deficit promotes chronic inflammatory and oxidative stresses, hyperexcitability and, in mice, susceptibility to audiogenic seizures. Potentiation by low-magnesium concentrations of the opening of N-methyl-D-aspartate (NMDA) receptor/calcium channel in in vitro and ex vivo studies, and responsiveness to magnesium of in vivo brain injury states are now well established. By contrast, little or no specific attention has been, however, paid to the in vivo NMDA receptor function/excitability in magnesium deficiency. The present work reports for the first time that, in mice undergoing chronic nutritional deprivation in magnesium (35 v. 930 parts per million for 27 d in OF1 mice), NMDA-induced seizure threshold is significantly decreased (38 % of normal values). The attenuation in the drop of NMDA seizure threshold (percentage of reversal) was 58 and 20 % upon acute intraperitoneal administrations of magnesium chloride hexahydrate (28 mg magnesium/kg) and the antioxidant ebselen (20 mg/kg), respectively. In nutritionally magnesium-deprived animals, audiogenic seizures are completely prevented by these compound doses. Taken as a whole, our data emphasise that chronic magnesium deprivation in mice is a nutritional in vivo model for a lowered NMDA receptor activation threshold. This nutritional model responds remarkably to acute magnesium supply and moderately to acute antioxidant administration.

Impact of cyclosporine A on magnesium homeostasis: clinical observation in lung transplant recipients and experimental study in mice.

BACKGROUND: Hypomagnesemia is a common finding in patients receiving cyclosporine A (CsA) therapy. The relationship between CsA-induced hypomagnesemia and nephrotoxicity and the effects of oral magnesium (Mg) supplementation remain unclear. After a retrospective analysis of the time-course of plasma Mg and creatinine levels in lung allograft recipients treated with both CsA and oral Mg supplementation, we investigated the effects of CsA treatment on Mg homeostasis in mice with normal or Mg-deficient diet and the effects of oral Mg supplementation on plasma Mg levels. METHODS: Thirty lung-allograft recipients entered the retrospective study. One thousand two hundred twenty-eight blood samples were analyzed for blood and creatinine levels. Cyclosporine A (50 mg/kg/day by intraperitoneal injection) was administered to mice maintained on normal diet (1400 ppm) or Mg-deficient (50 ppm) diet. Magnesium levels were determined in plasma, urine, feces and femur, and creatinine levels were determined in plasma and urine. RESULTS: Plasma Mg concentration declines from the day of transplantation in 36.7% of the patients despite Mg supplementation, without correlation with creatinine changes. In mice, CsA induced an early moderate hypomagnesemia, which could not be ameliorated by oral Mg supplementation and was aggravated by low-Mg dietary, late increase in plasma creatinine and decrease in urine creatinine without histological signs of renal injury, decrease in intestinal Mg absorption and Mg mobilization from bone. CONCLUSION: Cyclosporine A treatment may induce moderate hypomagnesemia that is aggravated by inadequate Mg intake and is not ameliorated by Mg supplementation. Because of the clinical complications of hypomagnesemia, Mg should be monitored regularly in allograft recipients receiving CsA.

Effect of hypomagnesemia on allogeneic activation in mice.

INTRODUCTION: Magnesium (Mg) plays an essential role in a wide range of fundamental cellular reactions. It has been reported that in rodents Mg-deficient diet-induced hypomagnesemia results in an early inflammation. We have previously shown that chronic severe hypomagnesemia was associated neither with endothelial cell activation nor with an inflammatory process which are crucial in the allograft rejection process. T cell allogeneic stimulation activates the phosphatase calcineurin which triggers the signaling pathways leading to IL-2 synthesis and lymphocyte proliferation. Full activation of calcineurin requires Mg. Surveys suggest that a significant number of people consume less Mg than the international dietary reference intakes leading to hypomagnesemia in 2.5% to 15% of the general population. OBJECTIVE: The aim of the study was to investigate the effects of hypomagnesemia on lymphocyte allogeneic activation and proliferation in a murine model of dietary-induced hypomagnesemia. METHODS: C57BL/6J (H-2(b), Mls(b)) mice were given normal Mg-containing diet (1400 ppm Mg, control mice), or synthetic Mg-deficient diets containing either 50 ppm Mg or 150 ppm Mg for 28 days. Serum Mg levels were determined at days 5, 14 and 28. In parallel, complete urine and faeces were collected by using metabolic cages during a 24 h period for Mg determinations. Splenocytes from C57BL/6 mice fed either normal diet or 50 ppm Mg-diet were used as responder cells in mixed lymphocyte reaction (MLR) performed with splenocytes from C3H/He mice (H-2(k), Mls(IIa)) and C57BL/6 mice fed normal diet as stimulators for allogeneic and isogeneic conditions, respectively. TGF-beta and IL-2 productions were quantified in the supernates of mixed splenocytes cultures. 3x10(6) splenocytes from mice fed 50 ppm Mg-diet were used for calcineurin activity determination at day 28. RESULTS: In mice fed 150 ppm Mg-diet, moderate hypomagnesemia was observed from day 5 to day 28. Oral supplementation with Mg pidolate (5 or 20 mg Mg/kg/day) could not restore normal serum Mg levels. Serum Mg concentration early decreased in mice fed 50 ppm Mg-diet to achieve stabilized severe hypomagnesemia at days 14 and 28. Urine Mg concentration early dramatically fell down then stabilized in mice fed Mg-deficient diets. In MLR performed at day 28 with splenocytes from mice fed 50 ppm Mg-diet, proliferation and IL-2 production in allogeneic conditions were similar to control mice. No TGF-beta production was detected in any group. Lastly, calcineurin activity measured at day 28 was significantly lower in splenocyes from mice fed 50 ppm Mg-diet than in mice fed control diet. CONCLUSION: Mg-deficiency does not alter splenocyte allogeneic activation and proliferation and IL-2 production in vitro, although it partially inhibits calcineurin activity. We hypothesize that the remaining activity is sufficient for IL-2 gene normal activation. Alternatively, Mg-deficiency may trigger other signaling pathways leading to IL-2 production.

Neuroprotective gene profile in the brain of magnesium-deficient mice.

BACKGROUND: Magnesium (Mg) deficiency may lead to serious metabolic, biological and organic dysfunctions, and cause various clinical disorders. In the current study, we explore endothelial cell activation, inflammation and cell death induced in the brain of adult mice by Mg-deficient diet. METHODS AND RESULTS: Neither TNFalpha, substance P, sTNFRI, sTNFRII proteins (ELISA), nor TNFalpha, adherence molecules and prolactin mRNAs, nor NK1R (immunohistochemistry on brain sections) were up-regulated. No inflammatory infiltrates and no apoptotic cells were observed. Using cDNA assay, we showed a neuroprotective, anti-apoptotic and neurotrophic gene expression profile in the brain at early stage of hypomagnesemia. As a model for neuronal injury, mild sound stimulation of Mg-deficient mice without convulsive seizures triggers neither the release of substance P, nor the development of an inflammatory process or cell death in the brain. CONCLUSION: Our results suggest that Mg-deficiency in mice favours the development of a neuroprotective environment in the brain.

The PPARgamma agonist FMOC-L-leucine protects both mature and immature brain.

(N-[9-fluorenylmethoxycarbonyl]-)-L-leucine (FMOC-L-leucine) and rosiglitazone, two ligands of peroxisome proliferator-activated receptor gamma (PPARgamma), were evaluated in mature (adult mice) and immature (pups) brain injury models. In adult magnesium-deficient mice, a model responsive to both neuroprotective and anti-seizure compounds, FMOC-L-leucine, but not rosiglitazone, protected against audiogenic seizures. The protection afforded by FMOC-L-leucine was alleviated by the PPARgamma antagonist GW9662 (1-2 mg/kg) and was induced in 50% animals by 4.8+/-1.2 mg/kg. At this dose, FMOC-L-leucine modified audiogenic seizure phase durations in convulsing mice differently than prototype antiepileptic drugs did. FMOC-L-leucine (up to 100 mg/kg) was inactive in the 6 Hz seizure test, an adult animal model largely responsive to anti-seizure drugs. In a model of neonatal brain injury, FMOC-L-leucine (4 microg/kg) was neuroprotective against cerebral ibotenate toxicity. It reduced significantly the size of lesions in grey but not in white matter, while rosiglitazone (10 microg/kg) was inactive. Taken as a whole, the present data support neuroprotective potentialities of FMOC-L-leucine towards both mature and immature brain. The PPAR-based protection of immature brain is more important as it is known that classic adult brain protectants (GABA(A) activators, N-methyl-D-aspartate and sodium channel blockers) may be toxic for immature brain. The PPARgamma agonist FMOC-L-leucine is likely to be devoid of these classic protective mechanisms because of its inactivity in the 6 Hz seizure test, its activity in the audiogenic test being explained by neuroprotective rather than intrinsic anti-seizure mechanisms. Targeting PPARs might be thus a promising way to protect immature brain.

Allogeneic activation is attenuated in a model of mouse lung perfused with magnesium-deficient blood.

Hypomagnesemia, which is frequently observed in patients treated with calcineurin inhibitors to prevent rejection after allogeneic transplantation, has been associated with a faster rate of decline in allograft function. The effect of hypomagnesemia on lung allograft has not been reported yet. In our model of isolated mouse lung, we have evaluated the early effects of allogeneic lung perfusion with blood from magnesium (Mg)-deficient mice for 3 h on lung activation and remodelling, compared to isogeneic perfusion. Hypomagnesemia (0.21+/-0.07 mmol Mg(2+)/l) was observed in blood from Mg-deficient mice, but no inflammatory pattern. The mRNA level of the intercellular adhesion molecule (ICAM)-1, but neither of the vascular cell adhesion molecule (VCAM)-1, nor of the cytokines tumor necrosis factor (TNF)alpha and interleukin (IL)-2, was enhanced (p<0.05). Although caspase-3 mRNA was transiently enhanced, no apoptotic cells were evidenced in lung tissues even after 3 h. Using cDNA array, we found that the genes encoding RANKL, RANK, TNFR2, NFATX, IL-1R2, IL-6R gp130, SOCS3, PDGFRB, P63, CSF3R, CXCL1, CXCL5, CX3CL1, CSF1, which are involved in inflammation and apoptosis regulation, were markedly up-regulated in allogeneic conditions. Our results support a limited allogeneic activation and an early stage of the inflammatory process in lung, at the time of inflammatory cell recruitment without lung tissue remodelling, as a result of hypomagnesemia. These findings suggest that cyclosporine-related hypomagnesemia, observed in most of the transplanted patients, does not constitute an additional risk for lung allograft outcome.

Headache due to photosensitive magnesium depletion.

Clinical and paraclinical data (visual stress tests, electroencephalographic and cerebrovascular photic driving, visual evoked potentials) demonstrate that the concept of photosensitive headache is fully justified. The interictal hallmark of photosensitive cephalalgic patients is potentiation (or sensitization) instead of habituation. The aetiopathogenic mechanisms of photosensitive headache associate hypofunction of the biological clock and magnesium depletion. The new concept of headache due to photosensitive magnesium depletion seems justified. It appears logical to add the treatments of magnesium depletion and of photosensitivity to classical treatment of headache. Prophylactic magnesium treatment relies on atoxic nutritional magnesium supplementation in case of primary magnesium deficiency. Pharmacological doses of parenteral magnesium may be used but may induce toxicity. Therefore it is necessary to know the therapeutic index of magnesium compound used: the larger its value, the greater the safety margin. Treatment of photosensitivity uses various types of <>: darkness therapy through physiologic, psychotherapic, physiotherapic, pharmacologic stimulating techniques and substitutive darkness therapy through palliative treatment. Melatonin is only a partial substitutive treatment of photosensitivity. A new model of photosensitive magnesium depletion with potentiation should be a useful tool for discriminating the most efficient gent.

New data on the importance of gestational Mg deficiency.

Chronic primary Mg deficiency is frequent. Around 20% of the population consumes less than two-thirds of the RDA for Mg, in both genders and in women particularly: for example, in France, 23% of women and 18% of men. Primary Mg deficiency may occur in fertile women. Gestational Mg deficiency is able to induce maternal, fetal, and pediatric consequences which might last throughout life. Experimental studies of gestational Mg deficiency show that Mg deficiency during pregnancy may have marked effects on the processes of parturition and of postuterine involution. It may interfere with fetal growth and development from teratogenic effects to morbidity: i.e. hematological effects and disturbances in temperature regulation. Clinical studies on the consequences of maternal primary Mg deficiency in women have been insufficiently investigated. To check the validity of the role of this frequent gestational Mg deficiency, the protocol of a long term multicentric placebo controlled prospective study on the effects of maternal nutritional Mg supplementation on lethality and morbidity in fetus, neonates, infants, children and adults should be carried out not only during pregnancy and the first year of life, but throughout life. Two clinical forms of chronic gestational Mg deficiency in women have been stressed: Premature labor when chronic maternal Mg deficiency is involved in uterine hyperexcitability, Sudden Infant Death Syndrome (SIDS) when it is caused by either simple Mg deficiency or various forms of Mg depletion. Nutritional Mg treatment of premature labor. If gestational Mg deficiency is the only cause for uterine overactivity, nutritional Mg supplementation constitutes the etiopathogenic atoxic tocolytic treatment. But although it is an adjuvant factor in premature labor, it is only a useful accessory treatment, devoid of toxicity but which increases the effectiveness and safety of the associated tocolytic drugs such as beta-2 mimetics. SIDS due to gestational Mg deficit: Mg deficiency or various forms of Mg depletion. SIDS may be caused by the fetal consequences of maternal Mg deficiency through an impaired control of Brown Adipose Tissue (BAT) thermoregulation, mechanisms leading to a modified temperature set point. SIDS may result from dysthermias: hypo- or hyperthermic forms. A possible prevention could rest on simple maternal nutritional Mg supplementation. Various stresses in pregnant women or in the infant may transform a simple Mg deficiency into Mg depletion: stress in baby care such as bedding in prone position, environmental factors such as parental smoking, but the role of chronopathological stress particularly appears to be too often neglected as it constitutes a clinical form of primary hypofunction of the biological clock [with its anatomical and clinical stigma such as reduced production of melatonin (MT) and of its urinary metabolite: 6 Sulfatoxy-Melatonin (6 SMT)]. SIDS might be linked to an impaired maturation of both the photoneuroendocrine system and BAT. A preventive treatment of this form of SIDS should associate atoxic nutritional Mg therapy for pregnant women with total light deprivation at night for the infant. The place of Mg therapy for the infant and of MT, L Tryptophan and taurine is uncertain for the moment.

Magnesium research: from the beginnings to today.

The beginnings of magnesium research, from the 18th century to the first quarter of the twentieth century, consists mainly of the development of chemical and pharmacological knowledge. The modern period began in 1926 when the essential character of magnesium was acknowledged. The early part of the modern period, up to the 1960s, saw the foundation of our knowledge of the basic physiological, epidemiological and clinical aspects. The present modern period began in 1971 with the First International Symposium on Magnesium and the subsequent creation of SDRM (the international Society for the Development of Research on Magnesium), an international coordinating structure, which promotes the publication of magnesium books (volumes of proceedings and monographs) and of journals: Magnesium Research the international official organ of SDRM and several national journals: the Journal of Japanese Society for Magnesium Research (Japan), the Buletin informativ al societatii romane de cercetare a magneziului (Romania), the Journal of Elementology (Poland) and which regularly organizes national and international meetings. The next great international meeting will be held on October 23-26, 2006 in Osaka (Japan). We will discuss the latest research findings on magnesium in health and disease. The subject shows that today magnesium research remains active in basic sciences and embraces all the facets of pathology.

Beta-2 mimetics and magnesium: true or false friends?

Physiological beta stimulation may be involved in the regulation of magnesium status namely by homeostatic increase of magnesemia during magnesium deficiency. But conversely excessive beta stimulation namely by use of pharmacological high doses of beta mimetics may induce a decrease of magnesemia. Two different types of magnesium therapy ought to be distinguished. Nutritional magnesium therapy which may physiologically palliate a magnesium deficiency due to an insufficient magnesium intake. It is devoid of any toxicity. Pharmacological magnesium therapy, whatever the magnesium status, causes a iatrogenic magnesium load. It may induce magnesium toxicity. Tocolysis is the one common obstetrical indication for beta mimetics and magnesium. Beta-2 mimetics are the reference tocolytic drugs in most countries. But high doses of beta-2 mimetics for suppression of premature labor are associated to a high incidence of maternal, fetal and neonatal side effects. Tocolysis must then be discontinued or limited to shorter treatments with the lowest possible doses. Nutritional magnesium therapy which palliates gestational magnesium deficiency is efficient and atoxic. Conversely, high doses of intravenous MgSO4 for tocolysis are less efficient and unsafe. Because of its maternal and above all pediatric side effects, this maternal pharmacological magnesium therapy should be abandoned for tocolysis. Investigation of the therapeutic ratio of various magnesium salts before their clinical use could help to determine if other anions different from sulfate could decrease the toxicity. Beta-2 agonists are first line asthma therapy, but their safety is debated. Asthma and Chronic Obstructive Pulmonary Disease (COPD) per se may induce magnesium depletion related to a dysregulation of the control mechanisms of magnesium status. It requires a correction of its causal regulation, but nutritional magnesium supplementation is ineffective. When chronic primary magnesium deficiency coexists with obstructive bronchial disorders, it constitutes a decompensatory factor. Atoxic nutritional magnesium therapy may palliate this coexistent magnesium deficiency. Pharmacological magnesium treatment for obstructive pulmonary diseases is not very efficient with low safety. Combination of palliating nutritional magnesium therapy and of beta-2 mimetics for tocolysis or pulmonary obstructive indications may be beneficial and remain atoxic. Conversely combination of intravenous tocolytic high doses of magnesium and of beta-2 mimetics is contra-indicated because of its dubious efficiency and its possible toxicity. The possible role of SO4- as regards toxicity must be discussed. Contra-indications of lower intravenous or inhaled Mg doses for pulmonary bronchial obstruction are less imperative than for tocolysis. The selection of a particular magnesium salt among others should take into account reliable plasmacological and toxicological data. It seems necessary to determine the therapeutic ratio (LD50/ED50) of the various available magnesium salts before pharmacological use.

Potent mammalian cerebroprotection and neuronal cell death inhibition are afforded by a synthetic antioxidant analogue of marine invertebrate cell protectant ovothiols.

Implicit strategies for neuroprotection in the adult brain include GABAA receptor activation, N-methyl-d-aspartate receptor and sodium voltage-gated channel inhibition. Ironically, these same targets may be harmful to the immature or developing brain. Protection has been demonstrated for both immature and mature brain with the use of a synthetic ovothiol analogue. The following beneficial effects have been demonstrated in mice: protection against audiogenic seizures, brain structures with clear-cut delineation of ibotenate-challenged white and grey matter lesions along with exceptional early and delayed protections, and potent cerebral cell death inhibition. The compound lacks both GABAergic activity and sodium channel blocker properties, which may help explain the lack of toxicity normally expressed in an immature brain utilizing these agents [J.W. Olney (2002) Neurotoxicology, 93, 1-10]. The oxidized form of the compound is virtually devoid of antioxidant activity. In vivo it exhibits cerebroprotective properties similar to those of reduced compounds endowed with antioxidant properties. This unexpected finding has prompted an extensive in vitro exploration of underlying molecular mechanisms that have led to the identification of several recycling mechanisms consistent with non rate-limiting conversion of oxidized to reduced compound forms. Taken as a whole, this work offers an unique combined in vitro and in vivo support that: (i). antioxidant therapy, here engineered from marine invertebrate egg protectants, may be a valuable strategy in protecting both mammalian adult and developing brain; and (ii). recycling (thiol-disulphide exchange) properties of the oxidized form of an antioxidant compound are as important as the antioxidant potential exhibited by a bioactive reduced antioxidant in certain neuroprotective processes.

THC aggravates rat muricide behavior induced by two levels of magnesium deficiency.

A severe magnesium deprivation induces an interspecific aggressive behavior (muricidal behavior, MB) in different strains of rats. Delta9-tetrahydrocannabinol (THC) is also known to induce MB even after a single injection (11 mg/kg) in starving, isolated rats. In the present work, we investigated the MB behavior, for six successive assays 1 h delayed, of two groups of male Long-Evans rats fed 50- or 150-ppm Mg(2+)-deficient diets, for 42 days after a single injection of THC at doses (2, 4 or 8 mg/kg) that did not induce aggressiveness in control rats. This treatment led to Mg(2+) plasma levels of 5+/-0.3 and 12.3+/-0.9 mg/ml vs. 21+/-1.5 mg/ml initially. In the 50-ppm Mg-deficient rat group, all the rats were muricidal but the MB pattern was severely aggravated by THC. In the 150-ppm Mg-deficient rat group, no rat was muricidal but all doses of THC induced a 100% MB. In addition, by quantifying the three phases of MB, we showed through six consecutive hourly muricidal assays, that the two first phases (attack latency and attack on the living mouse) decreased progressively, whereas the third phase (attack on the dead mouse) increased dramatically. This indicates firstly that Mg-deprivation decreases the responsiveness threshold of rats to THC. Secondly, these very low doses of THC induced an aggravation of MB and an acquired hyper-aggressiveness in both 50- and 150-ppm Mg-deficient rats, probably involving different neurotransmitters, mainly serotonin, which is decreased by both treatments.

Biorhythms and possible central regulation of magnesium status, phototherapy, darkness therapy and chronopathological forms of magnesium depletion.

Biological clock and magnesium status are linked. Central magnesium regulation may be hypothetized. Balanced magnesium status is requested to obtain efficiency of suprachiasmatic nuclei and of pineal gland. Conventional bright light therapy appears as a speedy and efficient antidepressant medication useful for the treatment of various types of depression, and of non migrainous headaches also. Although decrease in melatonin production seems accessory, increases of serotonergy and perhaps of Reactive Oxygen Species constitute the main mechanisms of action. Chromatotherapy emphazizes the effects of short exposure to specific colors. Although the increased production of melatonin constitutes the best marker of darkness, it is only an accessory mechanism of its action. The psycholeptic sedative effects of darkness, like those of magnesium, rely on direct membraneous and oxidant actions, neural mediated effects (i.e. stimulation of inhibitory neuromodulators such as GABA and taurine), and on antagonism of neuroactive gases (CO and NO). Darkness therapyper se, partial substitutive therapy with melatonin and with their mimicking agents (Mg, L-Tryptophan,Taurine) apply to all the chronopathological forms of magnesium depletion with decreased production of melatonin: sleep disorders, migraine, chronic fatigue syndrome, fibromyalgia, some forms of asthma and of sudden infant death syndrome. Further research should assess the importance of the chronopathological forms of magnesium depletion in the physiopathology of these disorders.