Effect of magnesium on nitric oxide synthase of neurons in cortex during early period of cerebral ischemia

Magnesium and the Brain: A Focus on Neuroinflammation and Neurodegeneration

Magnesium (Mg) is involved in the regulation of metabolism and in the maintenance of the homeostasis of all the tissues, including the brain, where it harmonizes nerve signal transmission and preserves the integrity of the blood-brain barrier. Mg deficiency contributes to systemic low-grade inflammation, the common denominator of most diseases. In particular, neuroinflammation is the hallmark of neurodegenerative disorders. Starting from a rapid overview on the role of magnesium in the brain, this narrative review provides evidences linking the derangement of magnesium balance with multiple sclerosis, Alzheimer's, and Parkinson's diseases.

A feasibility study of using biodegradable magnesium alloy in glaucoma drainage device

Technological advances in glaucoma have challenged the traditional treatment paradigm. Historically incisional surgery has been used in cases of advanced disease and/or uncontrolled intraocular pressures resistant to medical or laser interventions. More recently, perhaps due to advancements in imaging, surgery has been suggested to be beneficial earlier in the treatment paradigm. Despite these trends, surgical manipulation of the tissues and unpredictability of wound healing continue to result in surgical failure. Magnesium is an essential element for human body and plays a critically important role in maintaining the functional and structural integrity of several tissues, including the eye. Due to several of its advantageous properties such as non-toxicity, biodegradability, and high biological compatibility, magnesium alloy has attracted great attention as a novel biomaterial. Biodegradable cardiovascular stents made of magnesium alloy have already been introduced into clinical practice. The purpose of this review is to determine if bioabsorbable magnesium alloys can be utilized as a promising candidate for the development of a new generation of glaucoma surgical assistive devices.

Pathogenetic role of magnesium deficiency in ophthalmic diseases

Magnesium is one of the most important regulatory cation involved in several biological processes. It is important for maintaining the structural and functional integrity of several vital ocular tissues such as cornea, lens and retina. The magnesium content of lens, especially in its peripheral part, is higher than that in aqueous and vitreous humor. Magnesium has also been shown to play critically important role in retinal functions. Magnesium plays significant role as a cofactor for more than 350 enzymes in the body and regulates neuroexcitability and several ion channels. Membrane associated ATPase functions that are crucial in regulating the intracellular ionic environment, are magnesium-dependent. Moreover, the enzymes involved in ATP production and hydrolysis are also magnesium-dependent. Magnesium deficiency by interfering with ATPase functions causes increased intracellular calcium and sodium and decreases intracellular potassium concentration. Such ionic imbalances in turn alter the other cellular enzymatic reactions and form the basis of the association of magnesium deficiency with ophthalmic diseases such as cataract. In presence of magnesium deficiency, an imbalance between mediators of vasoconstriction and vasorelaxation may underlie the vasospasm, which is one of the pathogenic factors in primary open angle glaucoma. Furthermore, magnesium deficiency is also a contributing factor in increased oxidative stress and inducible NOS stimulation that can further contribute in the initiation and progression of ocular pathologies such as cataract, glaucoma and diabetic retinopathy. In this paper we review the association of disturbances of magnesium homeostasis with several ophthalmic diseases.

Natural plant products and extracts that reduce immunoexcitotoxicity-associated neurodegeneration and promote repair within the central nervous system

Our understanding of the pathophysiological and biochemical basis of a number of neurological disorders has increased enormously over the last three decades. Parallel with this growth of knowledge has been a clearer understanding of the mechanism by which a number of naturally occurring plant extracts, as well as whole plants, can affect these mechanisms so as to offer protection against injury and promote healing of neurological tissues. Curcumin, quercetin, green tea catechins, balcalein, and luteolin have been extensively studied, and they demonstrate important effects on cell signaling that go far beyond their antioxidant effects. Of particular interest is the effect of these compounds on immunoexcitotoxicity, which, the authors suggest, is a common mechanism in a number of neurological disorders. By suppressing or affecting microglial activation states as well as the excitotoxic cascade and inflammatory mediators, these compounds dramatically affect the pathophysiology of central nervous system disorders and promote the release and generation of neurotrophic factors essential for central nervous system healing. We discuss the various aspects of these processes and suggest future directions for study.

Effects of magnesium sulfate administration during hypoxia on Ca(2+) influx and IP(3) receptor modification in cerebral cortical neuronal nuclei of newborn piglets

Magnesium is a non-competitive antagonist of the NMDA receptor. Hypoxic insults to the brain are associated with a significant increase in the intranuclear Ca(2+) due to altered nuclear membrane Ca(2+) influx mechanisms including hypoxia-induced modifications of nuclear membrane IP(3) receptors. In this study we have examined the effects of magnesium sulfate administration to newborn piglets subjected to normoxia and severe hypoxia. The animals were randomly divided into normoxic (n=4), hypoxic (n=4) and magnesium sulfate treated hypoxic (n=4) groups. Hypoxia was confirmed biochemically by measuring ATP and phosphocreatine (PCr) levels in the brain tissue. Intranuclear Ca(2+) influx was assessed by measuring (45)Ca(2+) uptake. Results show a significant (P<0.05) decrease in ATP and PCr levels in hypoxic group in comparison with normoxia. On the other hand magnesium-treated hypoxic group showed a significantly (P<0.05) higher ATP and PCr in comparison with the hypoxic group. Intranuclear Ca(2+) was significantly (P<0.05) higher in the hypoxic group in comparison with both normoxic and magnesium-treated hypoxic groups. In addition results show that magnesium prevented hypoxia-induced modification of the IP(3) receptor. Magnesium treatment significantly reduced the hypoxia-induced increase in the number of receptors (reduced B(max) --P<0.05-treated hypoxia vs. hypoxia and normoxia), and reversed the receptor affinity (reduced dissociation coefficient-K(d)--P<0.05-treated hypoxia vs. normoxia). The results demonstrate that the administration of magnesium sulfate prior to hypoxia prevents the hypoxia-induced increase in intranuclear Ca(2+) and IP(3) receptor modifications. We conclude that Mg(2+ )administration prevents hypoxia-induced modification of neuronal nuclear membrane function that leads to intranuclear Ca(2+)-dependent transcription of apoptotic proteins leading to hypoxic neuronal programmed cell death.

Rapid inhibition of the glutamate-induced increase of intracellular free calcium by magnesium in rat hippocampal neurons

By using Fura-2/AM, the effects of magnesium (Mg2+) on the glutamate-induced increase of intracellular free calcium ([Ca2+]i) in the cultured hippocampal neurons and the features were investigated by integrated photoelectric detecting system. The experiments were designed to three groups (The drug was spit to the cells for 20 s): Group A receiving 1 x 10(-5) mol/L glutamate; Group B receiving 1 x 10(-5) mol/L glutamate and 1 x 10(-5) mol/L Mg2+ simultaneously; Group C receiving 1 x 10(-5) mol/L glutamate again after [Ca2+]i in group B back to the baseline. The results showed that in group A, [Ca2+]i was obviously increased. In group B, the changes in [Ca+] i and the peak value were significantly decreased. Moreover, the elevation of Phase 1 was slowed down and Phase 2 was shortened to some extent, and the plateau phase between them was relatively prolonged. In group C, calcium oscillation similar to that in group A occurred, but both the Phase 1 and Phase 2 were shortened and the delta[Ca2+]i was slightly decreased. It was suggested that Mg2+ could quickly inhibit the rise of [Ca2+]i induced by glutamate in the cultured hippocampal neurons in rats.