The causal role of magnesium deficiency in the neuroinflammation, pain hypersensitivity and memory/emotional deficits in ovariectomized and aging mice

Abstract

Background: Postmenopausal women often suffer from chronic pain, memory decline and mood depression. The mechanisms underlying the neuronal disorders are not fully understood and effective treatment is still lacking.Methods: Oral administration of magnesium-L-threonate was tested to treat the neuronal disorders in ovariectomized and aging mice. The pain hypersensitivity, memory function and depression were measured with a set of behavioral tests. Western blots and immunochemistry were used to assess molecular changes.Results: Chronic oral administration of magnesium-L-threonate substantially prevented or reversed the chronic pain, and memory/emotional deficits in both ovariectomized and aging female mice. We found that phospho-p65, an active form of nuclear factor-kappaB, tumor necrosis factor-alpha and interleukin-1beta were significantly upregulated in the neurons of dorsal root ganglion, spinal dorsal horn and hippocampus in ovariectomized and aging mice. The microglia and astrocytes were activated in spinal dorsal horn and hippocampus. The peptidergic C-fibers in dorsal horn were increased, which are associated with potentiation of C-fiber-mediated synaptic transmission in the model mice. In parallel with neuroinflammation and synaptic potentiation, free Mg2+ levels in plasma, cerebrospinal fluid and dorsal root ganglion neurons were significantly reduced. Oral magnesium-L-threonate normalized the neuroinflammation, synaptic potentiation and Mg2+ deficiency, but did not affect the estrogen decline in ovariectomized and aging mice. Furthermore, in cultured dorsal root ganglion neurons estrogen elevated intracellular Mg2+, and depressed the upregulation of phospho-p65, tumor necrosis factor-alpha and interleukin-1beta exclusively in the presence of extracellular Mg2+.Conclusions: Estrogen decline in menopause causes neuroinflammation by reducing intracellular Mg2+ in neurons, leading to chronic pain, memory/emotional deficits. Thus, supplement Mg2+ by oral magnesium-L-threonate may be a novel approach for treating menopause-related neuronal disorders.