Major depressive disorder and anxiety disorders together represent one of the largest sources of disability worldwide, and both remain difficult to treat [1,2]. A substantial share of patients fails to respond to first-line antidepressants, and relapse after apparent remission is common [3,4]. Ketamine and esketamine, antagonists of N-Methyl-D-aspartate (NMDA) receptors, have shown that correcting glutamatergic and Ca²⁺ signaling abnormalities can produce rapid symptomatic improvement even in treatment-resistant cases, but their use is constrained by abuse liability, dissociative side effects, and the need for monitored administration [5,6]. There is accordingly considerable interest in identifying other agents that act on the same upstream Ca²⁺ -handling machinery with minimal side effects and toxicity. Dantrolene, a ryanodine receptor (RyR) antagonist and a clinically available drug to treat malignant hyperthermia, has been demonstrated to inhibit NMDA-mediated elevation of cytosolic Ca²⁺ concentration by as much as 78% in cortical neurons [7]. Our recent study makes a notable contribution to this effort by repurposing intranasal dantrolene nanoparticles in Ryanodex formulation for the treatment of depression and anxiety [8].

Using a well-established LPS-injection model of neuroinflammation-associated mood disturbance, the authors show that four weeks of daily intranasal dantrolene nanoparticles in Ryanodex formulation [9,10] pretreatment substantially blunts the depressive-like (forced swim test, tail suspension test) and anxiety-like (elevated plus maze, open field test) behaviors that follow a single intraperitoneal LPS challenge. Mechanistically, dantrolene pretreatment suppressed the LPS-induced rise in the pyroptosis-associated cytokines IL-1β and IL-18 in both serum and brain, attenuated activation of the NLRP3-caspase-1-GSDMD pyroptotic cascade (most clearly for cleaved caspase-1), and preserved the synaptic proteins PSD-95 and synapsin-1, both markers of dendritic spine integrity that are typically eroded by neuroinflammatory insults. Vehicle-treated animals did not share in these benefits, arguing against a nonspecific effect of the nanoparticle carrier itself. An intriguing secondary observation was that behavioral protection was more consistent and robust in female mice than in male mice, a pattern the authors link to the higher clinical prevalence of depression in women and to previously proposed hormonal and stress-axis explanations for that sex disparity.

The conceptual appeal of this work lies in its intervention in the pathological cascade. Much of the field's therapeutic effort in inflammation-associated depression has focused on cytokines themselves or on  downstream neurotransmitter systems. Here, the authors target RyR-mediated Ca²⁺ release from the endoplasmic reticulum (ER), a step upstream of mitochondrial dysfunction, oxidative stress, and inflammasome assembly, as a proposed mechanism. If RyR overactivation is genuinely an early node feeding into pyroptotic cell death, cytokine release, and synapse loss, then a RyR antagonist should in principle produce broader protection than agents aimed at a single downstream mediator. Furthermore, the multi-endpoint improvement reported here (behavior, circulating cytokines, brain cytokines, pyroptosis markers, and synaptic proteins moving together) is consistent with that logic, even though the causal chain linking these endpoints needs further studies. More studies are needed to investigate the underlying effect and mechanism of dantrolene on inflammatory pyroptosis. Our recent study demonstrating dantrolene’s effectiveness to inhibit inflammatory pyroptosis in brains of 5XFAD mice [11], which may provide some assurance that dantrolene may be effective in inhibiting neuronal programmed cell death by pyroptosis.

The choice of intranasal nanoparticle delivery is also pertinent to translatability. Dantrolene is limited by its penetration into the brain [12]. Our earlier pharmacokinetic work, cited in the paper, indicates that intranasal delivery of dantrolene nanoparticles in Ryanodex formulation raises the brain-to-blood concentration ratio relative to oral or subcutaneous routes, and that chronic intranasal dosing up to 10 months in prior Alzheimer's disease models did not produce detectable nasal, hepatic, or muscular toxicity [9,10,13]. Although previous studies have demonstrated an increased brain-to-blood concentration ratio following dantrolene administration, this finding alone does not establish effective CNS target engagement. Nevertheless, intranasal dantrolene nanoparticles may enable lower doses than those required for traditional intravenous, subcutaneous, or oral administration, while still achieving therapeutically relevant CNS concentrations. By increasing CNS delivery while reducing systemic exposure, this approach could potentially lower peripheral blood dantrolene concentrations and minimize dose-related adverse effects, particularly the hepatotoxicity associated with chronic use. Notably, chronic use of dantrolene for up to 10 months did not significantly alter nasal tissue structure in mice [13]. However, because the ratio of nasal surface area to total body size is substantially lower in humans than in mice, the translational efficacy and safety of intranasal dantrolene nanoparticles remain to be established. Further studies in humans are therefore necessary to determine their CNS target engagement, therapeutic efficacy, and potential adverse effects.

The sex-difference finding deserves particular attention from readers in experimental neurology, where preclinical sex-stratified data remain underreported. That the anxiolytic and antidepressant-like effects of dantrolene were most pronounced in females is at minimum a signal that RyR-dependent mechanisms may be differentially weighted between sexes in stress- and inflammation-related psychiatric pathology, and it strengthens the rationale for including both sexes, and reporting them separately, in future mechanistic and dose-ranging studies of this compound class. Although these findings are consistent with the higher prevalence of depressive disorders among female patients, future studies with adequate statistical power are needed to investigate the underlying mechanisms and account for hormonal and estrous cycle status.

Depressive symptoms are highly prevalent across neurodegenerative diseases, affecting up to 50% of patients with Alzheimer's disease [14,15], 35% of stroke patients [16], and 40% of patients with amyotrophic lateral sclerosis (ALS) [17]. Dantrolene, particularly when delivered intranasally via nanoparticle formulations, has demonstrated neuroprotective effects across multiple animal models of these conditions: in models of Alzheimer's disease [10,18–20], cerebral ischemia [21–23], and, in our own recent work, in SOD1G93A transgenic mice, a widely used model of ALS [24]. Given this convergence of evidence, a single agent capable of both protecting against neurodegeneration and ameliorating the depression and anxiety that so commonly accompany these diseases would represent a particularly attractive therapeutic strategy.

A few aspects of the study temper how far its conclusions can presently be extended. First, this is a pretreatment paradigm: dantrolene was administered for four weeks before the inflammatory challenge, which models prevention rather than treatment of an already-established depressive or anxious state. Whether dantrolene nanoparticle treatment began after the onset of inflammation-associated behavioral change would produce comparable reversal is a clinically more relevant question. Second, the LPS single-injection paradigm captures acute neuroinflammatory mood disturbance but does not recapitulate the chronicity of clinical MDD or anxiety disorders. Therefore, validation in chronic stress or chronic low-dose LPS models would strengthen generalizability. Third, the pyroptosis data are uneven: NLRP3 and N-terminal GSDMD changes did not reach statistical significance despite trending in the expected direction, and only cleaved caspase-1 showed a clear effect. Thus, the mechanistic claim that dantrolene acts specifically through inhibition of pyroptosis, as opposed to a more general anti-inflammatory or Ca²⁺-stabilizing action, remains to be firmly established. Fourth, although dantrolene is extensively studied as an RyR antagonist, it may also have some off-target effects. Dantrolene has been demonstrated to inhibit NMDAR by antagonizing the glycine site [25] on NMDAR and to inhibit Ca²⁺ influx via NMDAR [26]. Thus, the current study has proposed a mechanism but has not confirmed the RyR-mediated Ca²⁺ dysregulation as a causal pathway. The effects of dantrolene on NMDAR warrant further study to determine whether its effects on intracellular Ca²⁺ concentrations result from inhibition of NMDAR, RyR, or both”. The authors are appropriately candid about this limitation. Finally, brain tissue was analyzed in bulk rather than by region, which may have obscured effects localized to structures classically implicated in mood regulation, such as the hippocampus, prefrontal cortex, or amygdala, and the absence of direct cytosolic or mitochondrial Ca²⁺ measurements leaves the core mechanism proposed rather than demonstrated.

Several experiments would meaningfully extend this work. Dose-response and treatment-after-onset studies are a priority, given that physiological ER Ca²⁺ release itself is necessary for normal neuronal signaling and excessive RyR blockade could have its own costs. Region-specific and cell-type-specific analyses (neuronal versus microglial versus astrocytic) would help clarify where dantrolene's protective effects are exerted. Direct measurement of reactive oxygen species and of cytosolic/mitochondrial Ca²⁺ flux would close the mechanistic gap between RyR inhibition and the downstream inflammatory and synaptic readouts reported here. Given the sex-difference finding, mechanistic studies stratified by sex and, eventually, by estrous/hormonal status would be valuable. Finally, because the model here is inflammation-induced rather than genetic- or chronic-stress-induced, cross-model replication would help establish whether dantrolene's benefits generalize across the heterogeneous biological routes to depressive and anxious phenotypes.

This study provides promising preclinical proof of concept for further investigation of RyR/Ca²⁺ signaling in inflammation-associated behavioral dysfunction. Confirmatory studies addressing treatment rather than prevention, timing, chronic models, regional and mechanistic specificity, and dose optimization will be important for determining whether intranasal dantrolene nanoparticles can advance toward clinical evaluation as a novel therapeutic approach for depression and anxiety with a potentially improved safety profile. Given previous evidence supporting the role of RyR/Ca²⁺ signaling and dantrolene in neurodegenerative disorders, including Alzheimer’s disease and amyotrophic lateral sclerosis, these findings may also have broader implications for future investigation of intranasal dantrolene as a therapeutic strategy across neurological and neuropsychiatric conditions.

Dr. Huafeng Wei is listed as an inventor of patents and an ongoing application entitled “Intranasal Administration of Dantrolene for Treatment of Alzheimer’s Disease” in multiple countries by The Trustees of the University of Pennsylvania. Dr. Huafeng Wei is listed as the inventor of the USA and an ongoing international patent application repurposing intranasal dantrolene nanoparticles with or without lithium to treat major depression disorder and amyotrophic lateral sclerosis (PCT/US2026/016152).

This work was supported by grants to HW from the National Institute on Aging (R01AG061447) and NIA R01 Supplemental (3R01AG061447-03S1).