Dantrolene

BackgroundHuntington's disease (HD) is a progressive neurodegenerative disorder caused by a polyglutamine expansion in the Huntingtin protein which results in the selective degeneration of striatal medium spiny neurons (MSNs). Our group has previously demonstrated that calcium (Ca2+) signaling is abnormal in MSNs from the yeast artificial chromosome transgenic mouse model of HD (YAC128). Moreover, we demonstrated that deranged intracellular Ca2+ signaling sensitizes YAC128 MSNs to glutamate-induced excitotoxicity when compared to wild type (WT) MSNs. In previous studies we also observed abnormal neuronal Ca2+ signaling in neurons from spinocerebellar ataxia 2 (SCA2) and spinocerebellar ataxia 3 (SCA3) mouse models and demonstrated that treatment with dantrolene, a ryanodine receptor antagonist and clinically relevant Ca2+ signaling stabilizer, was neuroprotective in experiments with these mouse models. The aim of the current study was to evaluate potential beneficial effects of dantrolene in experiments with YAC128 HD mouse model.ResultsThe application of caffeine and glutamate resulted in increased Ca2+ release from intracellular stores in YAC128 MSN cultures when compared to WT MSN cultures. Pre-treatment with dantrolene protected YAC128 MSNs from glutamate excitotoxicty, with an effective concentration of 100 nM and above. Feeding dantrolene (5 mg/kg) twice a week to YAC128 mice between 2 months and 11.5 months of age resulted in significantly improved performance in the beam-walking and gait-walking assays. Neuropathological analysis revealed that long-term dantrolene feeding to YAC128 mice significantly reduced the loss of NeuN-positive striatal neurons and reduced formation of Httexp nuclear aggregates.ConclusionsOur results support the hypothesis that deranged Ca2+ signaling plays an important role in HD pathology. Our data also implicate the RyanRs as a potential therapeutic target for the treatment of HD and demonstrate that RyanR inhibitors and Ca2+ signaling stabilizers such as dantrolene should be considered as potential therapeutics for the treatment of HD and other polyQ-expansion disorders.

Catecholaminergic polymorphic ventricular tachycardia (CPVT) is a highly malignant inherited arrhythmogenic disorder. Type 1 CPVT (CPVT1) is caused by cardiac ryanodine receptor (RyR2) gene mutations resulting in abnormal calcium release from sarcoplasmic reticulum. Dantrolene, an inhibitor of sarcoplasmic Ca(2+) release, has been shown to rescue this abnormal Ca(2+) release in vitro. We assessed the antiarrhythmic efficacy of dantrolene in six patients carrying various RyR2 mutations causing CPVT. The patients underwent exercise stress test before and after dantrolene infusion. Dantrolene reduced the number of premature ventricular complexes (PVCs) on average by 74% (range 33-97) in four patients with N-terminal or central mutations in the cytosolic region of the RyR2 protein, while dantrolene had no effect in two patients with mutations in or near the transmembrane domain. Induced pluripotent stem cells (iPSCs) were generated from all the patients and differentiated into spontaneously beating cardiomyocytes (CMs). The antiarrhythmic effect of dantrolene was studied in CMs after adrenaline stimulation by Ca(2+) imaging. In iPSC derived CMs with RyR2 mutations in the N-terminal or central region, dantrolene suppressed the Ca(2+) cycling abnormalities in 80% (range 65-97) of cells while with mutations in or near the transmembrane domain only in 23 or 32% of cells. In conclusion, we demonstrate that dantrolene given intravenously shows antiarrhythmic effects in a portion of CPVT1 patients and that iPSC derived CM models replicate these individual drug responses. These findings illustrate the potential of iPSC models to individualize drug therapy of inherited diseases.Trial Registration: EudraCT Clinical Trial Registry 2012-005292-14.

IntroductionNeuroleptic malignant syndrome (NMS) is a rare, but sometimes fatal, adverse reaction to neuroleptics characterized principally by fever and rigor. The aim of this study was to prove the efficacy of different NMS treatment strategies, focusing on the efficacy of dantrolene.MethodsAltogether, 271 case reports were included. These cases were categorized into four treatment groups and compared to each other according to effectiveness of therapy within 24 hours, mortality, complete time of remission in days, effectiveness due to increase of dosage, relapse on the basis of decrease of dosage, and improvement of symptoms.ResultsBetween the four treatment groups, the complete time of remission was significantly different (analysis of variance, F = 4.02; degrees of freedom = 3; p = 0.008). In a logistic regression with adjustment for age, gender, and severity code, no significant predictor of the treatment for the complete time of remission (dichotomized by median) could be found. However, if the premedication was a monotherapy with neuroleptics, the complete time of remission was significantly shorter with dantrolene monotherapy (t = -2.97; p = 0.004).ConclusionThe treatment of NMS with drugs that are combined with dantrolene is associated with a prolongation of clinical recovery. Furthermore, treatment of NMS with dantrolene as monotherapy seems to be associated with a higher overall mortality. Therefore, dantrolene does not seem to be the evidence-based treatment of choice in cases of NMS but might be useful if premedication consisted of a neuroleptic monotherapy.

This study investigates the therapeutic effectiveness of intranasal dantrolene nanoparticle pretreatment to inhibit lipopolysaccharide (LPS)-induced pathological inflammation, synapse destruction, and depressive and anxiety behavior in mice. B6SJLF1/J adult mice were pretreated with intranasal dantrolene nanoparticles (dantrolene: 5 mg/kg), daily, Monday to Friday, 5 days per week, for 4 weeks. Afterwards, mice were treated with a single intraperitoneal injection of LPS (5 mg/kg). Behavioral tests for depression and anxiety were performed 24 h after the one-time LPS injection. Biomarkers for pyroptosis-related inflammation cytokine levels (IL-1β and IL-18) in the blood and brain were measured using enzyme-linked immunosorbent assay (ELISA) and immunoblotting, respectively. Changes in primary protein (NLRP3: NLR family pyrin domain containing 3, Caspase-1, N-GSDMD: N-terminal protein gasdermin D) and synapse protein-related (PSD-95 and synaptin-1) activation of inflammatory pyroptosis in mouse brains were measured using immunoblotting. Results indicated that intranasal dantrolene nanoparticle treatment robustly inhibited LPS-induced increases in depressive and anxiety behavior, LPS-induced pathological elevation of IL-1β and IL-18 levels in the blood and brain, and LPS-induced activation of pyroptosis. Furthermore, intranasal dantrolene nanoparticles significantly inhibited decreased PSD-95 and synaptin-1 levels. Intranasal dantrolene nanoparticles have demonstrated neuroprotective effects against inflammation-mediated depression and anxiety behaviors and should be studied further as a future effective drug treatment of major depressive or anxiety disorders.