Biology subjects

Reilly, C. A.

Publications and source records attributed to Reilly, C. A..

9 recordsLinked to original sources

bioRxiv2024

Validation studies and multi-omics analysis of Zhx2 as a candidate quantitative trait gene underlying brain oxycodone metabolite (oxymorphone) levels and behavior

Sensitivity to the subjective reinforcing properties of opioids has a genetic component and can predict addiction liability of opioid compounds. We previously identified Zhx2 as a candidate gene underlying increased brain concentration of the oxycodone (OXY) metabolite oxymorphone (OMOR) in BALB/cJ (J) versus BALB/cByJ (By) females that could increase OXY state-dependent reward. A large structural intronic variant is associated with a robust reduction of Zhx2 expression in J mice, which we hypothesized enhances OMOR levels and OXY addiction-like behaviors. We tested this hypothesis by restoring the Zhx2 loss-of-function in Js (MVKO) and modeling the loss-of-function variant through knocking out the Zhx2 coding exon (E3KO) in Bys and assessing brain OXY metabolite levels and behavior. Consistent with our hypothesis, Zhx2 E3KO females showed an increase in brain OMOR levels and OXY-induced locomotor activity. However, contrary to our hypothesis, state-dependent expression of OXY-CPP was decreased in E3KO females and increased in E3KO males. We also overexpressed Zhx2 in the livers and brains of Js and observed Zhx2 overexpression in select brain regions that was associated with reduced OXY state-dependent learning. Integrative transcriptomic and proteomic analysis of E3KO mice identified astrocyte function, cell adhesion, extracellular matrix properties, and endothelial cell functions as pathways influencing brain OXY metabolite concentration and behavior. These results support Zhx2 as a quantitative trait gene underlying brain OMOR concentration that is associated with changes in OXY behavior and implicate potential quantitative trait mechanisms that together inform our overall understanding of Zhx2 in brain function.

neuroscience↗

bioRxiv2024

Development of a preclinical screening platform for clinically relevant therapy of Dravet syndrome

BackgroundPatients with drug-resistant epilepsy, including Dravet syndrome (DS), are frequently prescribed multiple antiseizure medications (ASMs). Nevertheless, people with DS often have inadequate seizure control, and there is an ongoing unmet clinical need to identify novel therapeutics. As a proof-of-principle study to further validate and characterize the Scn1aA1783V/WT mouse model and identify a drug screening paradigm with face, construct, and predictive value, we assessed the efficacy of subchronic administration of stiripentol add-on to clobazam and valproic acid at clinically relevant doses using the Scn1aA1783V/WT mouse model. MethodsWe evaluated the efficacy of STP add-on to CLB and VPA using hyperthermia-induced and video-EEG monitoring of spontaneous seizure tests following a 14-day treatment. VPA was delivered via osmotic minipump, while STP and CLB were administered via food pellets delivered through automatic feeders. Bioanalytical assays were performed to evaluate drug concentrations in plasma and brain using liquid chromatography-tandem mass spectrometry. ResultsSTP, CLB, N-desmethylclobazam, and VPA all yielded plasma concentrations within the human therapeutic plasma concentrations range. STP added to CLB and VPA significantly elevated the seizing temperatures in the hyperthermia-induced seizure assay. CLB, VPA, and STP coadministration significantly reduced spontaneous seizure frequency compared to CLB and VPA combined. SignificanceThis research lays the groundwork for exploring effective add-on compounds to CLB and VPA in treating DS. The study further highlights the utility of the Scn1aA1783V/WT mice in discovering therapies for DS-associated pharmacoresistant seizures. Key pointsO_LIIntegrating pharmacokinetic studies to guide the selection of doses in preclinical studies to achieve target concentrations comparable to the human therapeutic range is crucial in successfully translating animal drug development studies to clinical use. C_LIO_LISTP add-on to CLB and VPA significantly reduced spontaneous seizure frequency in Scn1aA1783V/WT mice. C_LIO_LIA triple-drug polytherapy approach that mimics the clinical treatment paradigm will be an essential preclinical drug screening strategy for identifying novel investigational compounds for Dravet syndrome. C_LI

pharmacology and toxicology↗

bioRxiv2023

Utilizing an acute hyperthermia-induced seizure test and pharmacokinetic studies to establish optimal dosing regimens in a mouse model of Dravet syndrome

ObjectiveThe current standard of care for Dravet Syndrome includes polytherapy after inadequate seizure control with one or more monotherapy approaches. Treatment guidelines are often based on expert opinions, and finding an optimal balance between seizure control and adverse drug effects can be challenging. This study utilizes efficacy and pharmacokinetic analysis of a second-line treatment regimen that combines clobazam and sodium valproate with an add-on drug as a proof-of-principle approach to establish an effective therapeutic regimen in a preclinical mouse model of Dravet Syndrome. MethodWe evaluated the efficacy of add-on therapies stiripentol, cannabidiol, lorcaserin, or fenfluramine to clobazam and sodium valproate against hyperthermia-induced seizures in Scn1aA1783V/WT mice. Clobazam, N-desmethyl clobazam (an active metabolite of clobazam), sodium valproate, stiripentol, and cannabidiol concentrations were quantified in plasma and brain using liquid chromatography-tandem mass spectrometry for the combinations deemed effective against hyperthermia-induced seizures. The concentration data were used to calculate pharmacokinetic parameters via non-compartmental analysis in Phoenix WinNonLin. ResultsHigher doses of stiripentol or cannabidiol, in combination with clobazam and sodium valproate, were effective against hyperthermia-induced seizures in Scn1aA1783V/WT mice. In Scn1aWT/WT mice, brain clobazam and N-desmethyl clobazam concentrations were higher in the triple-drug combinations than in the clobazam monotherapy. Stiripentol and cannabidiol brain concentrations were greater in the triple-drug therapy than when given alone. InterpretationA polypharmacy strategy may be a practical preclinical approach to identifying efficacious compounds for Dravet Syndrome. The drug-drug interactions between compounds used in this study may explain the potentiated efficacy of some combination therapies. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=163 SRC="FIGDIR/small/560653v1_ufig1.gif" ALT="Figure 1"> View larger version (42K): org.highwire.dtl.DTLVardef@70d9a7org.highwire.dtl.DTLVardef@e18a26org.highwire.dtl.DTLVardef@134c74aorg.highwire.dtl.DTLVardef@8065d_HPS_FORMAT_FIGEXP M_FIG C_FIG Key findingsThe hyperthermia-induced seizure assay in Scn1aA1783V/WT mice can identify efficacious antiseizure medications. A triple-drug administration paradigm was designed that mimics clinical standards for add-on therapies in DS. Stiripentol and cannabidiol were effective against hyperthermia-induced seizures when co-administered with clobazam and sodium valproate. Potential drug-drug interactions between compounds may explain the potentiated antiseizure effect in triple-drug therapies. The triple-drug "add-on" therapy approach may be a valuable preclinical strategy for screening investigational compounds for DS, an assay offered at the ETSP.

pharmacology and toxicology↗

bioRxiv2023

The mechanics of bronchoconstriction cause airway epithelial damage and inflammation by excess crowding-induced extrusion

Asthma is deemed an inflammatory disease, yet the defining diagnostic symptom is mechanical bronchoconstriction. We previously discovered a conserved process that drives homeostatic epithelial cell death in response to mechanical cell crowding called cell extrusion(1, 2). Here, we show that the pathological crowding of a bronchoconstrictive attack causes so much epithelial cell extrusion that it damages the airways, resulting in inflammation and mucus secretion. While relaxing airways with the rescue treatment albuterol did not impact these responses, inhibiting live cell extrusion signaling during bronchoconstriction prevented all these symptoms. Our findings propose a new etiology for asthma, dependent on the mechanical crowding of a bronchoconstrictive attack. Our studies suggest that blocking epithelial extrusion, instead of ensuing downstream inflammation, could prevent the feed-forward asthma inflammatory cycle.

cell biology↗

bioRxiv2022

Evaluating the efficacy of prototype antiseizure drugs using a preclinical pharmacokinetic approach

ObjectivePharmacokinetics (PK) of a drug drive its exposure, efficacy, and tolerability. A thorough preclinical PK assessment of antiseizure medications (ASMs) is therefore essential to evaluate the clinical potential. We tested protection against evoked seizures of prototype ASMs in conjunction with analysis of plasma and brain PK as a proof-of-principle study to enhance our understanding of drug efficacy and duration of action using rodent seizure models. MethodsIn vivo seizure protection assays were performed in adult male CF-1 mice and Sprague-Dawley rats. Clobazam (CLB), N-desmethylclobzam (NCLB), carbamazepine (CBZ), carbamazepine-10,11-epoxide (CBZE), valproic acid (VPA), and levetiracetam (LEV) concentrations were quantified in plasma and brain using liquid chromatography-tandem mass spectrometry. Mean concentrations of each analyte were calculated and used to determine PK parameters via non-compartmental analysis in Phoenix WinNonLin. ResultsNCLB concentrations were approximately 10-fold greater than CLB in mice. The antiseizure profile of CLB was partially sustained by NCLB in mice. CLB concentrations were lower in rats than in mice. CBZE plasma exposures were approximately 70% of CBZ in both mice and rats, likely contributing to the antiseizure effect of CBZ. VPA showed a relatively short half-life in both mice and rats, which correlated with a sharp decline in efficacy. LEV had a prolonged brain and plasma half-life, associated with a prolonged duration of action in mice. SignificanceThe study demonstrates the utility of PK analyses for understanding the seizure protection time-course in mice and rats. The data indicate that distinct PK profiles of ASMs between mice and rats likely drive differences in drug efficacy between rodent models. Key PointsO_LIThere exist potential contributions of active metabolites to the efficacy of some ASMs. C_LIO_LIThe utility of preclinical PK assessment of ASM is critical to guide our insight into a drug efficacy profile and provide a framework for subchronic dosing strategies. C_LIO_LISpecies-specific variations in PK profiles of ASMs in rodent models of epilepsy may underpin the differences in antiseizure effect in these models. C_LIO_LIPre-clinical drug screening of ASMs should include a (sub)chronic dosing paradigm to better mimic the dosing regimen in the clinic. C_LI

neuroscience↗

bioRxiv2022

Breathing dysfunction and alveolar damage in a mouse model of Dravet syndrome

ObjectiveThe incidence of Sudden Unexpected Death in Epilepsy (SUDEP) is especially high in those with Dravet syndrome (DS). Risk factors have been identified, but the mechanism(s) by which death occurs is not fully understood. Evidence supports ventilatory dysfunction in the pathophysiology of SUDEP. Understanding specific respiratory patterns present at baseline and after seizures at different ages, as well as the health of lung tissue, will allow us to better understand how sudden death occurs in this population. MethodsWhole body plethysmography (WBP) was used to monitor respiration before and after electrically induced seizure in the Scn1aA1783V/WT mouse model of DS weekly for a period of four weeks. Following the four-week WBP study, lungs from surviving animals were collected and stained with hematoxylin and eosin and Weigerts elastin and the density of tissue and elastin were analyzed. ResultsBreathing was diminished in the DS mouse at baseline and following evoked seizures in younger aged mice (P18-P24), consistent with prolonged post-ictal inspiratory time and low respiratory drive compared to the response seen in older animals. In older DS mice, consisting of those that have survived a critical period for mortality, the response to seizure was more robust and included higher respiratory drive, peak inspiratory and expiratory flow rates, tidal and expiratory volumes, and breathing frequency compared to wild-type and relative to baseline. Alveolar damage was also observed in P46-P52 DS mice. SignificanceDifferences in specific respiratory parameters in younger DS animals, during the time when mortality is greatest, compared to older DS animals (i.e. those that have survived the critical period) may allow us to better understand respiratory differences contributing to SUDEP. Lung tissue damage in DS may also contribute to respiratory dysfunction in SUDEP. KEY POINTSO_LIBaseline respiration is diminished in DS mice compared to wild type. C_LIO_LIElectrically induced seizure produced a different respiratory response in younger DS mouse compared to older DS animals. C_LIO_LIAlveolar septal damage is present in DS mice. C_LIO_LIBaseline and post-ictal breathing dysfunction and inefficient oxygenation and CO2 clearance likely potentiated by lung damage may serve as a potential mechanism by which SUDEP occurs in DS. C_LI

physiology↗

bioRxiv2022

Zhx2 is a candidate gene underlying oxymorphone metabolite brain concentration associated with state-dependent oxycodone reward

Understanding the pharmacogenomics of opioid metabolism and behavior is vital to therapeutic success as mutations can dramatically alter therapeutic efficacy and addiction liability. We found robust, sex-dependent BALB/c substrain differences in oxycodone behaviors and whole brain concentration of oxycodone metabolites. BALB/cJ females showed robust state-dependent oxycodone reward learning as measured via conditioned place preference when compared to the closely related BALB/cByJ substrain. Accordingly, BALB/cJ females also showed a robust increase in brain concentration of the inactive metabolite noroxycodone and the active metabolite oxymorphone compared to BALB/cByJ mice. Oxymorphone is a highly potent full agonist at the mu opioid receptor that could enhance drug-induced interoception and state-dependent oxycodone reward learning. Quantitative trait locus (QTL) mapping in a BALB/c F2 reduced complexity cross revealed one major QTL on chromosome 15 underlying brain oxymorphone concentration that explained 32% of the female variance. BALB/cJ and BALB/cByJ differ by fewer than 10,000 variants which can greatly facilitate candidate gene/variant identification. Hippocampal and striatal cis-expression QTL (eQTL) and exon-level eQTL analysis identified Zhx2, a candidate gene coding for a transcriptional repressor with a private BALB/cJ retroviral insertion that reduces Zhx2 expression and sex-dependent dysregulation of CYP enzymes. Whole brain proteomics corroborated the Zhx2 eQTL and identified upregulated CYP2D11 that could increase brain oxymorphone in BALB/cJ females. To summarize, Zhx2 is a highly promising candidate gene underlying brain oxycodone metabolite levels. Future studies will validate Zhx2 and its site of action using reciprocal gene editing and tissue-specific viral manipulations in BALB/c substrains. Significance StatementOur findings show genetic variation can result in sex-specific alterations in whole brain concentrations of bioactive opioid metabolites following oxycodone administration, and reinforces the need for sex as a biological factor in pharmacogenomic studies. The co-occurrence of female-specific increased oxymorphone and state-dependent reward learning suggests that this minor yet potent and efficacious metabolite of oxycodone could increase opioid interoception and drug-cue associative learning of opioid reward which has implications for cue-induced relapse of drug-seeking behavior.

pharmacology and toxicology↗

bioRxiv2021

Nicotinic acetylcholine receptor partial antagonist polyamides from tunicates and their predatory sea slugs

In our efforts to discover new drugs to treat pain, we identified molleamines A-E (1-5) as major neuroactive components of the sea slug, Pleurobranchus forskalii and their prey, Didemnum molle tunicates. The chemical structures of molleamines were elucidated by spectroscopy and confirmed by the total synthesis of molleamines A (1) and C (3). Synthetic 3 completely blocked acetylcholine-induced calcium flux in peptidergic nociceptors (PNs) in the somatosensory nervous system. Compound 3 affected neither the 7 nAChR nor the muscarinic acetylcholine receptors in calcium flux assays. In addition to nociceptors, 3 partially blocked the acetylcholine-induced calcium flux in the sympathetic nervous system, including neurons from the superior cervical ganglion. Electrophysiology revealed a block of 3{beta}4 (mouse) and 6/3{beta}4 (rat) nicotinic acetylcholine receptors (nAChRs), with IC50 values of 1.4 and 3.1 {micro}M, respectively. Molleamine C (3) is a partial antagonist, reaching a maximum block of 76-82% of the acetylcholine signal and showing no partial agonist response. Molleamine C (3) may thus provide a lead compound for the development of neuroactive compounds with unique biological properties.

neuroscience↗

bioRxiv2021

The tunicate metabolite 2-(3,5-diiodo-4-methoxyphenyl)ethan-1-amine targets ion channels of vertebrate sensory neurons

Marine tunicates produce defensive amino-acid derived metabolites, including 2-(3,5-diiodo-4-methoxyphenyl)ethan-1-amine (DIMTA), but their mechanisms of action are rarely known. Using an assay-guided approach, we found that out of the many different sensory cells in the mouse dorsal root ganglion (DRG), DIMTA selectively affected low-threshold cold thermosensors. Whole-cell electrophysiology experiments using DRG cells, channels expressed in Xenopus oocytes and human cell lines revealed that DIMTA blocks several potassium channels, reducing the magnitude of the afterhyperpolarization and increasing the baseline [Ca2+]i of low-threshold cold thermosensors. When injected into mice, DIMTA increased the threshold of cold sensation by >3 oC. DIMTA may thus serve as a lead in the further design of compounds that inhibit problems in the cold-sensory system, such as cold allodynia and other neuropathic pain conditions.

neuroscience↗