Oral administration of the KATP channel opener diazoxide ameliorates disease progression in a murine model of multiple sclerosis

Abstract

BackgroundMultiple Sclerosis (MS) is an acquired inflammatory demyelinating disorder of the central nervous system (CNS) and is the leading cause of nontraumatic disability among young adults. Activated microglial cells are important effectors of demyelination and neurodegeneration, by secreting cytokines and others neurotoxic agents. Previous studies have demonstrated that microglia expresses ATP-sensitive potassium (KATP) channels and its pharmacological activation can provide neuroprotective and anti-inflammatory effects. In this study, we have examined the effect of oral administration of KATP channel opener diazoxide on induced experimental autoimmune encephalomyelitis (EAE), a mouse model of MS.MethodsAnti-inflammatory effects of diazoxide were studied on lipopolysaccharide (LPS) and interferon gamma (IFNγ)-activated microglial cells. EAE was induced in C57BL/6J mice by immunization with myelin oligodendrocyte glycoprotein peptide (MOG35-55). Mice were orally treated daily with diazoxide or vehicle for 15 days from the day of EAE symptom onset. Treatment starting at the same time as immunization was also assayed. Clinical signs of EAE were monitored and histological studies were performed to analyze tissue damage, demyelination, glial reactivity, axonal loss, neuronal preservation and lymphocyte infiltration.ResultsDiazoxide inhibited in vitro nitric oxide (NO), tumor necrosis factor alpha (TNF-α) and interleukin-6 (IL-6) production and inducible nitric oxide synthase (iNOS) expression by activated microglia without affecting cyclooxygenase-2 (COX-2) expression and phagocytosis. Oral treatment of mice with diazoxide ameliorated EAE clinical signs but did not prevent disease. Histological analysis demonstrated that diazoxide elicited a significant reduction in myelin and axonal loss accompanied by a decrease in glial activation and neuronal damage. Diazoxide did not affect the number of infiltrating lymphocytes positive for CD3 and CD20 in the spinal cord.ConclusionTaken together, these results demonstrate novel actions of diazoxide as an anti-inflammatory agent, which might contribute to its beneficial effects on EAE through neuroprotection. Treatment with this widely used and well-tolerated drug may be a useful therapeutic intervention in ameliorating MS disease.

Diazoxide enhances excitotoxicity-induced neurogenesis and attenuates neurodegeneration in the rat non-neurogenic hippocampus

“…Recently, we and others have reported novel roles for Dzx as an anti-inflammatory agent, which could contribute to the neuroprotective effects. Dzx has been shown to prevent microglial TNF , NO and interleukin-6 production after activation with different stimuli in vitro (Zhou et al, 2008;Virgili et al, 2011). Here, our in vivo results demonstrated that Dzx preserves neurons and decreases microglial reaction against an excitotoxic neurodegenerative insult, possibly through its anti-inflammatory action.…”

“…Other studies in different animal models have shown that Dzx protects against cell death from excitotoxicity or inflammation, generating beneficial outcomes (Zhou et al, 2008;Liu et al, 2010;Virgili et al, 2011) and modulating the innate immune response (Virgili et al, 2014).…”

“…Different CNS cell types, including neurons (Humphries and Dart, 2015), oligodendrocytes (Fogal et al, 2010) and microglia (Virgili et al, 2011;Ortega et al, 2012), express K ATP channels as a combination of Kir6.2 and SUR1 subunits. K ATP channels are also expressed by endothelial cells, where they could be involved on the vascular response to physiological events (Rosenblum, 2003).…”

“…It is clear that K ATP channel is a major component of the inflammatory response following brain injury. We and others have demonstrated that it regulates the reactive state of microglia, controls the release of inflammatory mediators, such as nitric oxide (NO) and tumor necrosis factor-alpha (TNFα), and modifies phagocytic activity (Zhou et al, 2008;Virgili et al, 2011;Ortega et al, 2012). Despite these findings, the role of K ATP channel in the neurogenesis associated with inflammatory conditions is still largely unknown.…”

“…Half of the animals (6 rats in each group) were used for biochemical studies and the other half were used for histological investigations (Figure 1). The Dzx and NMDA doses were chosen according to previous studies (Virgili et al, 2011;Rodríguez et al, 2013;Batlle et al, 2015).…”