Biology subjects

Rho, J. M.

Publications and source records attributed to Rho, J. M..

6 recordsLinked to original sources

bioRxiv2025

Inhibition of phosphodiesterase 4B as a novel therapeutic strategy for the treatment of refractory epilepsy

Despite the availability of nearly 40 approved anti-seizure medications (ASMs), at least one-third of individuals with epilepsy remain refractory to treatment, and many experience life-limiting cognitive or psychiatric side effects. Using a machine learning-guided platform, we identified PDE4 as an underexplored anti-seizure target, which became further validated based on its enriched expression in seizure-relevant brain regions and its potential to modulate excitatory/inhibitory neuronal tone via cAMP signaling. The pan-PDE4 inhibitor crisaborole partially protected against hyperthermia-induced seizures and reduced spontaneous seizures in Scn1a+/- mice, while rolipram and roflumilast showed no efficacy at tolerable doses. SN-2000, a first-in-kind allosteric modulator of PDE4B, was rationally designed for isoform selectivity and brain penetration, and demonstrated versatile reduction of seizure activity across multiple zebrafish and rodent genetic and acquired epilepsy models, with efficacy comparable to standard-of-care ASMs. SN-2000 also demonstrated favorable behavioral outcomes, reducing post-ictal aggression and anxiety-like behaviors, and improving cognitive performance in both wild-type and epileptic mice. These effects were linked to paradoxical regulation of excitatory and neuronal activity in the cortex and thalamus of epileptic mice, respectively, as well as elevated cAMP signaling and downstream pCREB activation. Together, these findings support PDE4B inhibition as a disease-relevant mechanism in epilepsy, and position SN-2000 as a promising therapeutic candidate offering seizure control without the neuropsychiatric burden of existing ASMs and potential pro-cognitive properties. One Sentence SummarySN-2000, a novel allosteric PDE4 inhibitor, reduces seizure activity and shows psychiatric-neutral and pro-cognitive properties in preclinical models

neuroscience↗

bioRxiv2025

A ketogenic diet mitigates hippocampal astrogliosis in epileptic brain

The ketogenic diet (KD) is an established treatment for patients with medically intractable epilepsy and is chiefly characterized by high fat/low-carbohydrate intake and the production of ketone bodies (KB) such as {beta}-hydroxybutyrate (BHB). However, after more than a century of clinical use, the mechanisms underlying its efficacy remain unclear. While prior investigations have examined the effects of the KD and its metabolic substrates on synaptic transmission, few studies have explored a potential connection between astrocytic ion channels and seizure genesis. One essential function of astrocytes is spatial potassium buffering which influences passive potassium conductance (PPC), and when impaired, can result in neuronal hyperexcitability. In the present study, we demonstrate that the KD can mitigate hippocampal astrogliosis in the Kcna1-null (KO) mouse model of developmental epilepsy. Specifically, we observed a significant increase in GFAP expression in KO mice fed a control diet compared to wild-type (WT) mice, and that the KD prevented this change. Furthermore, we noted a reduction in hippocampal astrocytic PPC in epileptic mice, whereas KD-treated KO animals exhibited nearly normal passive conductance levels. In this regard, we found that while Kir4.1, TREK-1 and TWIK-1 RNA expression levels were not significantly altered by KD treatment in either WT or KO mice, BHB appeared to only minimally affect Kir4.1-mediated currents in transfected HEK cells. Furthermore, bulk RNA-seq analysis of the various treatment groups revealed KD-induced down-regulation of factors linked to hippocampal astrogliosis. Our findings indicate that the KD protects against epilepsy-associated astrogliosis and astrocytic PPC changes, underscoring a novel mechanism of action, and implicate extracellular potassium in its anti-seizure effects.

neuroscience↗

bioRxiv2023

Improving vocal communication with a ketogenic diet in a mouse model of autism

BackgroundDeficits in social communication and language development is a hallmark of autism spectrum disorder currently with no cure. Interventional studies using animal models have been very limited in demonstrating improved vocal communication. Autism has been proposed to involve metabolic dysregulation. Ketogenic diet (KD) is a metabolism-based therapy for medically intractable epilepsy, and its applications in other neurological conditions have been increasingly tested. However, how it would affect vocal communication has not been explored. The BTBR mouse strain is considered a model of idiopathic autism. They display robust deficits in vocalization during social interaction, and have metabolic changes implicated in autism. MethodsWe investigated the effects of KD on ultrasonic vocalizations (USVs) in juvenile and adult BTBR mice during male-female social encounters. ResultsAfter a brief treatment with KD, the amount, spectral bandwidth, and much of the temporal structure of USVs were robustly improved in both juvenile and adult BTBR mice. Composition of call categories and transitioning between individual call subtypes was more effectively improved in juvenile BTBR mice. LimitationsAlthough sharing certain attributes, mouse vocalization is unlikely to model all aspects in the development and deficits of human language. KD is highly restrictive and can be difficult to administer, especially for many people with autism who have narrow food selections. Side effects and potential influence on development should also be considered. Future studies are required to tease apart the molecular mechanisms of KDs effects on vocalization. ConclusionsTogether, our data provide further support to the hypothesis that metabolism-based dietary intervention could modify disease expression, including core symptoms, in autism.

animal behavior and cognition↗

bioRxiv2022

kcna1a mutant zebrafish as a model of episodic ataxia type 1 and epilepsy

ObjectiveKCNA1 mutations are associated with a rare neurological movement disorder known as episodic ataxia type 1 (EA1), with epilepsy as a common comorbidity. Current medications only provide partial relief to ataxia and/or seizures, making new drugs needed. Here, we investigate the utility of zebrafish kcna1a-/- as a model of EA1 with epilepsy by characterizing its phenotype and comparing the efficacy of the first-line therapy carbamazepine in kcna1a-/- zebrafish to Kcna1-/- rodents. MethodsWe used CRISPR/Cas9 mutagenesis to introduce a mutation in the sixth segment of the zebrafish Kcna1 protein. Behavioral and electrophysiological assays were performed on kcna1a-/- larvae to assess ataxia- and epilepsy-related phenotypes. We also carried out real-time qPCRs to measure the transcript levels of brain hyperexcitability markers and bioenergetic profiling of kcna1a-/- larvae to evaluate their metabolic health. Carbamazepine efficacy was tested using behavioral assessments in kcna1a-/- zebrafish and seizure frequency in Kcna1-/- mice. Resultskcna1a-/- zebrafish showed uncoordinated movements and locomotor deficits. The mutants also exhibited impaired startle responses when exposed to light-dark flashes and acoustic stimulation. Extracellular field recordings and upregulated fosab transcript levels showed hyperexcitability of the kcna1a-/- brain. Further, vglut2a and gad1b transcript levels were altered, indicative of neuronal excitatory/inhibitory imbalance in the kcna1a-/- brain. Metabolic health was also compromised in kcna1a-/- as seen by a significant reduction in measures of cellular respiration. Notably, carbamazepine reduced the impaired startle response in kcna1a-/- zebrafish but had no effect on the seizure frequency in Kcna1-/- mice, suggesting that this EA1 zebrafish model might better translate to human efficacy compared to rodents. SignificanceWe conclude that zebrafish kcna1a-/- larvae show ataxia and epilepsy-related phenotypes and that they are responsive to carbamazepine treatment, consistent with EA1 patients. This study supports the notion that these zebrafish disease models can be useful for drug screening as well as studying the underlying disease biology. KEY POINTSO_LIZebrafish kcna1a-/- larvae display dynamic behavioral changes, along with ataxia-like uncoordinated movements and brain hyperexcitability C_LIO_LIkcna1a-/- larvae have dysfunctional neuronal excitatory/inhibitory balance and perturbed metabolic health C_LIO_LISimilar to its effectiveness in patients, carbamazepine treatment improves behavioral deficits in kcna1a-/- larvae C_LI

neuroscience↗

bioRxiv2022

Sudden unexpected death in epilepsy is prevented by blocking postictal hypoxia

Epilepsy is at times a fatal disease. Sudden unexpected death in epilepsy (SUDEP) is the leading cause of mortality in people with intractable epilepsy and is defined by exclusion; non-accidental, non-toxicologic, and non-anatomic causes of death. While SUDEP often follows a bilateral tonic-clonic seizure, the mechanisms that ultimately lead to terminal apnea and then asystole remain elusive and there is a lack preventative treatments. Based on the observation that discrete seizures lead to local vasoconstriction, resulting in hypoperfusion, hypoxia and behavioural disturbances in the forebrain (Farrell et al., 2016), we reasoned that similar mechanisms may play a role in SUDEP when seizures invade the brainstem. Here we tested this neurovascular-based hypothesis of SUDEP in awake non-anesthetized mice by pharmacologically preventing seizure-induced vasoconstriction, with cyclooxygenase-2 or L-type calcium channel antagonists. In both acute and chronic mouse models of SUDEP, ibuprofen and nicardipine extended life. We also examined the potential role of spreading depolarization in the acute model of SUDEP. These data provide a proof of principle for the neurovascular hypothesis of SUDEP and the use of currently available treatments to prevent it.

neuroscience↗

bioRxiv2021

Pharmacokinetics and Central Accumulation of Delta-9-Tetrahydrocannabinol (THC) and its Bioactive Metabolites are Influenced by Route of Administration and Sex

Up to a third of North Americans over 16 years old report using cannabis in the prior month, most commonly through inhalation. Animal models that reflect human cannabis consumption are critical to study its impacts on brain and behaviour. Nevertheless, most animal studies to date examine effects of cannabis through injection of delta-9-tetrahydrocannabinol (THC; primary psychoactive component of cannabis). THC injections produce markedly different physiological and behavioural effects than inhalation, likely due to distinctive pharmacokinetics of each administration route. The current study directly examined if administration route (injection versus inhalation), with dosing being matched on peak THC blood levels, alters the metabolism of THC, and the central accumulation of THC and its metabolites over time. Adult male and female Sprague-Dawley rats received either a single intraperitoneal injection of THC (2.5 mg/kg) or a single (15 min) session of inhaled exposure to THC distillate (100 mg/mL) vapour. Blood and brains were collected at 15, 30, 60, 90 and 240 minutes post-exposure for analysis of THC and metabolites through mass spectrometry-liquid chromatography. Inhalation results in immediate hypothermia, whereas injection results in delayed hypothermia. Despite achieving comparable peak concentrations of blood THC in both groups, our results indicate higher initial brain THC concentration following inhalation, whereas injection resulted in dramatically higher 11-OH-THC concentrations, a potent THC metabolite, in blood and brain that increased over time. Our results provide evidence that THC and its metabolites exhibit different pharmacokinetic profiles following inhalation versus injection, which could have significant impacts for data interpretation and generalizability. Accordingly, we suggest that translational work in the realm of THC and cannabis strongly consider using inhalation models over those that employ injection. HighlightsO_LIBody temperature as well as blood and brain levels of THC and metabolites differ based on administration route C_LIO_LITHC inhalation results in immediate hypothermia, whereas THC injection results in delayed hypothermia C_LIO_LITHC inhalation results in higher initial brain THC levels than injection C_LIO_LITHC injection results in higher blood & brain 11-OH-THC levels than inhalation C_LIO_LITranslational cannabis work should strongly consider using inhalation over injection C_LI

neuroscience↗