Experimental design and analysis and their reporting II: updated and simplified guidance for authors and peer reviewers

Presence of dysfunctional soluble guanylate cyclase in mesenteric resistance arteries from rats with mild ligature-induced periodontitis

Periodontitis is notable for its high prevalence in the oral cavity and its association with systemic diseases. Functional alterations in vasomotor activity occur in the arteries of rats with mild periodontitis, primarily due to decreased soluble guanylate cyclase (sGC) enzyme activity. This study aims to investigate the functional response of mesenteric resistance arteries (MRA) obtained from rats with mild periodontitis. Vascular reactivity of MRAs from rats in the ligature (L) or sham (S) groups was assessed using a wire myograph. Additionally, antioxidant enzyme activity, the presence of nitrated proteins, cyclic guanosine monophosphate (cGMP) levels, and electron paramagnetic resonance (EPR) spectroscopy were analyzed. The MRAs from the L group showed lower pD2 values in response to sodium nitroprusside or sildenafil and decreased Emax to the sGC stimulator Bay 41-2271 compared to the S group. However, no differences were observed between the groups with respect to the sGC activator Bay 60-2770. The L group exhibited increased nitrotyrosine protein expression, enhanced catalase activity, and reduced superoxide dismutase activity, along with decreased cGMP content after SNP stimulation. The EPR spectrum of the L group showed a weak peak at g 6.00, compared to the S group, confirming the oxidation of sGC heme-iron (Fe+2) to heme-Fe+3. In the early phase of bilateral ligature-induced periodontitis in rats, functional changes in the nitric oxide (NO)-cGMP pathway occur in the MRA due to reduced sGC activity and excessive production of iNOS-derived NO, superoxide anion, or a combination of both.

Sex differences in the vasoactive effect of transient receptor potential channels: TRPM3 as a new therapeutic target for (neuro)vascular disorders

BACKGROUND AND PURPOSE

Sex-dependent vascular effects of transient receptor potential (TRP) channels and sex dimorphism in migraine are not yet fully characterized. We investigated the differential vasoactive effects of TRP ankyrin 1 (TRPA1), TRP melastatin 3 (TRPM3) and TRP vanilloid 1 (TRPV1) channels, their pharmacological mechanism(s), and localization and expression in human isolated blood vessels.

EXPERIMENTAL APPROACH

Agonist responses to cinnamaldehyde (TRPA1), pregnenolone sulfate (PregS, TRPM3) or capsaicin (TRPV1) were analysed using wire myography in segments of human coronary (HCAs) and middle meningeal (HMMAs) arteries from men and women. The mechanisms involved in these responses were investigated using the antagonists/blockers/inhibitors: HC-030031 (TRPA1), isosakuranetin (TRPM3), capsazepine (TRPV1), olcegepant (calcitonin gene-related peptide [CGRP] receptor), L-NAME (nitric oxide synthase [NOS]), indomethacin (cyclooxygenase [COX]), TRAM-34 + apamin (K+ channels) or MK-801 (N-methyl-d-aspartate [NMDA] receptor). Fluorescence microscopy, quantitative polymerase chain reaction (qPCR), and western blotting were performed to investigate their location and expression, respectively.

KEY RESULTS

In HCAs and HMMAs, (i) capsaicin-induced relaxation remained unchanged after the above-mentioned antagonists/blockers/inhibitors and (ii) cinnamaldehyde-induced relaxation was blocked by olcegepant. PregS-induced maximal relaxation was significantly enhanced in isolated arteries from females compared with males and was inhibited after isosakuranetin, MK-801 or L-NAME. TRPM3 mRNA and protein expression, along with NMDA protein levels, were higher in arteries from females than males.

CONCLUSION AND IMPLICATIONS

Modulation of vascular tone in HCAs and HMMAs by activation of TRPM3 is sex-dependent, likely involving NMDA receptors. This represents a new therapeutic direction, targeting sex dimorphism in migraine and its related cardiovascular events.

A novel butyrylcholinesterase inhibitor induces antidepressant, pro-cognitive, and anti-anhedonic effects in Flinders Sensitive Line rats: The role of the ghrelin-dopamine cascade

BACKGROUND AND PURPOSE

Major depressive disorder (MDD) is often treatment resistant, particularly in addressing anhedonia and cognitive deficits. Novel pharmacological strategies are needed. While butyrylcholinesterase, ghrelin, and dopamine (DA) have been well studied in the context of stress and MDD, their interaction remains unclear.

EXPERIMENTAL APPROACH

The dose-dependent antidepressant effects of a novel butyrylcholinesterase inhibitor (BChEI) were evaluated in the Flinders Sensitive Line (FSL) rat model of MDD. Behavioural assessments included the forced swim test (despair), sucrose preference test (reward-related), and novel object recognition test (cognition). Brain-derived neurotrophic factor (BDNF), acetylcholine (ACh), and brain monoamines were analysed, as well as serum growth hormone and acyl- and desacyl-ghrelin. To confirm the role of ghrelin, pharmacological exploration was undertaken using the ghrelin receptor antagonist, D-Lys-3-GHRP-6.

KEY RESULTS

FSL rats had significantly lower ghrelin ratios, BDNF, ACh, DA and growth hormone levels. In FSL rats, both BChEI and escitalopram significantly reduced despair. BChEI significantly outperformed escitalopram in enhancing reward-related and cognitive behaviours. Biochemically, BChEI treatment significantly increased ghrelin ratios and brain DA levels without altering brain 5-HT, ACh or BDNF. D-Lys-3-GHRP-6 significantly reversed the antidepressant-like, rewarding, and pro-cognitive effects of BChEI, accompanied by significant reductions in BDNF and DA.

CONCLUSIONS AND IMPLICATIONS

FSL rats display impaired ghrelin, DA, serotonin, growth hormone, and BDNF signalling, akin to MDD. BChEI exerts antidepressant-like effects across despair, reward, and cognitive domains, most likely via the BChE-ghrelin-DA cascade. Reversal of these effects by ghrelin antagonism underscores the critical role of ghrelin, specifically via growth hormone secretagogue receptor-ghrelin interaction. These findings suggest a potentially novel multimodal neurobiological target for the treatment of MDD.

Casdatifan (AB521) is a novel and potent allosteric small molecule inhibitor of protumourigenic HIF-2α dependent transcription

BACKGROUND AND PURPOSE

Hypoxia-inducible factor 2α (HIF-2α) is a transcription factor that mediates the expression of genes critical for cell adaptation and survival in low oxygen (hypoxic) conditions. In cancer, hypoxic conditions or molecular alterations within cancer cells can lead to HIF-2α accumulation and promote tumour growth and progression. Inactivating mutations in the von Hippel-Lindau (VHL) gene disable the oxygen-dependent HIF-2α degradation pathway and cause constitutive HIF-2α activity. VHL mutations are prevalent in clear cell renal cell carcinoma (ccRCC) where HIF-2α is a known tumourigenic driver. HIF-2α inhibition was shown to improve ccRCC patient outcomes clinically, warranting development of next-generation inhibitors.

EXPERIMENTAL APPROACH

Pharmacological effects of a novel small molecule allosteric inhibitor of HIF-2α, AB521 (casdatifan), were evaluated using in vitro cell-based assays and in vivo mouse models.

KEY RESULTS

AB521 inhibited HIF-2α-mediated transcription in cancer cells, endothelial cells, and M2-polarised macrophages. AB521 was selective for HIF-2α, displaying no activity against HIF-1α, and did not exhibit off-target cytotoxicity. When delivered orally to mice, AB521 caused dose-dependent decreases in HIF-2α-associated pharmacodynamic markers and significant regression of human ccRCC xenograft tumours. AB521 combined favourably with cabozantinib, a standard of care tyrosine kinase inhibitor, or zimberelimab, a clinical-stage anti-PD-1 antibody, in ccRCC xenograft studies.

CONCLUSIONS AND IMPLICATIONS

AB521 is a potent, selective and orally bioavailable HIF-2α inhibitor, with favourable pharmacological properties, that is being explored clinically for the treatment of ccRCC.

Design of antinociceptive peptide by grafting domains between scorpion β-neurotoxins

Neurotoxic peptides from venomous animals have been pointed out as antinociceptive therapeutic leads. Venom peptides have modulation properties on isoforms of voltage-gated sodium channels (VGSC), associated with pathologies such as neuropathic or inflammatory pain. The β-neurotoxins obtained from scorpion venoms are peptides that can alter the kinetics of VGSC by binding to its receptor site 4. CeII8 is a non-lethal scorpion β-neurotoxin that has been reported to interact with hNaV1.7, a VGSC isoform related to the codification and processing of painful stimulus (nociception), and it is involved in pain pathologies. On the other hand, CssII is a lethal scorpion β-neurotoxin that binds mainly to site 4 of hNav1.6. Because of this, we used computational methods and the amino acid sequence of the novo recombinant neurotoxin rCssII-RCR to graft in some of its domains existing amino acids from the non-lethal CeII8 to generate a chimeric peptide with antinociceptive activity, named rCssII-Del-D23A-TCD. This peptide variant was found to have antinociceptive activity in inflammatory and neuropathic pain models with an effect comparable to the mu-opioid receptor agonists DAMGO (H-Tyr-D-Ala-Gly-N(Me) Phe-Gly-ol).

Comprehensive evaluation of AChE inhibition by Eulophia ochreata extract utilizing in silico, ex vivo, and in vivo zebrafish models

Dementia commonly accompanies various neurodegenerative conditions, notably Alzheimer's disease. The pursuit of natural therapies for these diseases and their related symptoms has garnered widespread global interest. The present study aimed to explore the potential of Eulophia ochreata L. extract, containing phenanthrene active compounds, as an acetylcholinesterase (AChE) inhibitor. Analytical techniques confirmed the presence of phenanthrene compounds in the extract, which were then screened for AChE inhibition through molecular docking, ex vivo assays, and scopolamine-induced cognitive deficits in zebrafish larvae. These phenanthrene compounds, found in the extract of Eulophia ochreata L., exhibited a similar affinity for AChE as the standard drug Donepezil, with comparable interactions. Ex vivo assays using zebrafish larvae lysate and mouse brain homogenate indicated dose-dependent AChE inhibition with increasing extract concentrations. Behavioral assessments, including T and Y maze tests, revealed significant cognition improvement in extract-treated larvae having scopolamine-induced cognitive dysfunction, particularly at 1.3 µg/mL concentration. The combined results from molecular docking, ex vivo assays, and in vivo cognition deficit models underscored the potential of Eulophia ochreata L. extract as an AChE inhibitor, suggesting its phytochemicals could hold therapeutic promise, indicating further validation in mammalian models for translation into clinical therapies.

α-Adrenoreceptor blocker phentolamine inhibits voltage-gated sodium channels via the local anaesthetic binding site

BACKGROUND AND PURPOSE

Phentolamine is a non-selective α-adrenoreceptor antagonist used to reverse local anaesthesia, for example, during dental procedures when a vasoconstrictor is co-applied. Phentolamine-mediated vasodilation leads to faster clearance of injected drugs. Previous electrophysiological studies hypothesized that phentolamine acts as a modulator of voltage-gated sodium channels, which could conflict with its indication as local anaesthetic reversal agent.

EXPERIMENTAL APPROACH

We performed manual and high throughput patch-clamp recordings on HEK and CHO cells expressing NaV1.7 and NaV1.5. We investigated the effects of phentolamine on sodium channel biophysics and the additive impact of phentolamine on cells preconditioned with the local anaesthetic mexiletine. We used site-directed mutagenesis, homology modelling and drug docking to identify phentolamine's binding site. We compared the effect on sodium channels with other clinically established α-adrenoreceptor antagonists.

KEY RESULTS

Phentolamine inhibits NaV1.7 in HEK and CHO cells with an IC50 value of 72 and 57 μM and NaV1.5 in CHO cells with an IC50 of 27 μM. Phentolamine enhances the tonic block induced by the local anaesthetic mexiletine. Phentolamine binds to sodium channels at the local anaesthetic receptor site. The α-adrenoreceptor antagonists alfuzosin, urapidil and phenoxybenzamine show lower potency on NaV1.5 and NaV1.7 in patch-clamp recordings.

CONCLUSIONS AND IMPLICATIONS

Phentolamine blocks voltage-gated sodium channels via the local anaesthetic receptor site. This may conflict with its current indication as an antidote for local anaesthetics. We propose alternative α-adrenoreceptor antagonists as possible candidates for local anaesthetic reversal because these are less potent inhibitors of both cardiac and neuronal voltage-gated sodium channels.

Macrocyclic diterpenoids from Stellera chamaejasme roots alleviate imiquimod-induced psoriasiform inflammation via STAT1/S100A9 signalling pathway

BACKGROUND AND PURPOSE

Psoriasis is a multisystem inflammatory disease with a significant impact on quality of life. Stellera chamaejasme, a medicinal plant used in traditional Chinese medicine, shows promise for the treatment of psoriasis. We identified diterpenoids in S. chamaejasme, including a new compound, stellchamain A (SA, 1), with notable antipsoriasis properties. This study explored the effects of SA on psoriasis to determine the mechanisms underlying the therapeutic efficacy of S. chamaejasme.

EXPERIMENTAL APPROACH

Compounds isolated by column chromatography were structurally identified using NMR spectroscopy. The effects of SA on IL-17A-treated HaCaT cell viability and apoptosis were assessed using CCK-8 and TUNEL assays. In vivo anti-psoriasis activity of SA was evaluated in a mouse model of imiquimod (IMQ)-induced psoriasis. Network pharmacology, surface plasmon resonance (SPR), drug affinity responsive target stability (DARTS), and cellular thermal shift assays (CETSA) were elucidated the interactions between SA and the targets.

KEY RESULTS

SA was isolated from S. chamaejasme along with nine known analogues (2-10). In vivo, SA reduced IMQ-induced epidermal thickness, hyperkeratosis, and perivascular inflammatory cell infiltration. Network pharmacology indicated that SA may function via the interleukin IL-17A/STAT1/S100A9 pathway. The results of SPR assays and molecular docking showed that SA binds to STAT1 with a KD value of 9.24 nM. DARTS and CETSA analyses confirmed a direct and relevant interaction between SA and STAT1.

CONCLUSION AND IMPLICATIONS

SA modulates the immunological microenvironment to treat psoriasis by targeting the IL-17A/STAT1/S100A9 axis, representing a potential new treatment for psoriasis and other IL-17A-mediated skin disorders.

GNS561 (ezurpimtrostat), a small basic lipophilic molecule, prevents lupus phenotype in a pristane-induced lupus mouse model

BACKGROUND AND PURPOSE

Systemic lupus erythematosus is an autoimmune, multisystemic disease affecting all organs in the body. Accrued evidence has elucidated a role for autophagy in the onset and severity of systemic lupus erythematosus. The antimalarial drug hydroxychloroquine constitutes the cornerstone of standard of care for systemic lupus erythematosus, together with glucocorticoids and immunosuppressants or biologics, and all accompanied by various side effects.

EXPERIMENTAL APPROACH AND OBJECTIVE

Our study aimed to investigate the potential of GNS561 (ezurpimtrostat) treatment, a small basic lipophilic molecule that induces lysosomal dysregulation, using the pristane-induced lupus mouse model.

KEY RESULTS

Compared with hydroxychloroquine, GNS561 treatment presents a more pronounced impact on the development of pathogenic anti-antibodies in pristane-induced lupus mice. Next, focussing on clinical impact, we showed that GNS561 significantly reduced clinical signs of lupus in pristane-induced lupus by preventing the incidence and severity of arthritis, occurrence of nephritis and lung damage. Finally, GNS561 modulated the inflammatory profile in pristane-induced lupus mice through a reduction of the lipogranuloma score. Interestingly, focussing on interferon-α, only pristane-induced lupus mice treated by GNS561 presented a significant decrease of the cytokine, suggesting a higher efficacy for GNS561 in the modulation of lupus-induced inflammation compared with hydroxychloroquine.

CONCLUSION

All results show that GNS561, but not hydroxychloroquine, represents as an effective treatment to prevent clinical and inflammatory signs of lupus in this mouse model.

IMPLICATIONS

Altogether, this study highlights GNS561 as a promising investigational drug for systemic lupus erythematosus.

GL-V9 inhibits Caspase-11 activation-induced pyroptosis by suppressing ALOX12-mediated lipid peroxidation to alleviate sepsis

BACKGROUND AND PURPOSE

Sepsis, caused by pathogen infection, poses a serious threat to human life. While the link between sepsis and pyroptosis via Caspase-11 non-canonical inflammasome activation is known, effective treatments remain lacking. Previous studies have confirmed that GL-V9 has antifibrotic and antitumor activities, but whether it has a therapeutic effect on sepsis is unclear. The aim of this study was to investigate the anti-inflammatory activity of GL-V9 and its possible mechanism.

EXPERIMENTAL APPROACH

The caecal ligation and puncture (CLP) model was used to assess the antiseptic effects of GL-V9 in vivo. Mouse bone marrow derived macrophages (BMDMs) and murine macrophages line J774A.1 also served as an in vitro Caspase-11 activation induced pyroptosis model. Cellular functions and molecular mechanism were analysed using cell viability assay, PI uptake assay, western blotting, immunofluorescence and co-immunoprecipitation.

KEY RESULTS

GL-V9 reduced tissue damage and mortality in mice with sepsis, and decreased the secretion of inflammatory factors in vivo. In vitro, GL-V9 suppressed Caspase-11-induced pyroptosis and prevented the release of LPS from early endosomes. Mechanistic studies revealed that GL-V9 limits Caspase-11 activation by inhibiting ALOX12-mediated lipid peroxidation. Further studies confirmed that GL-V9 did not further alleviate the symptoms and inflammatory response of septic mice in Alox12 deficient mice.

CONCLUSION AND IMPLICATIONS

GL-V9 exerts a powerful anti-sepsis effect in vivo, which is associated with the inhibition of Caspase-11 activation. Mechanistically, GL-V9 may block LPS release from early endosomes by inhibiting ALOX12-mediated lipid peroxidation. This suggests that GL-V9 is a potential candidate for the treatment of sepsis.

Baclofen modulates the immune response after spinal cord injury with locomotor benefits

BACKGROUND AND PURPOSE

Spinal cord injury (SCI) is a neurological condition that affects motor and sensory functions below the injury site. The consequences of SCI are devastating for the patients, and although significant efforts have been done in the last years, there is no effective therapy. Baclofen has emerged in the last few years as an interesting drug in the SCI field. Already used in the SCI clinical setting to control spasticity, baclofen has shown important impact on SCI recovery in animal models, such as lampreys and mice.

EXPERIMENTAL APPROACH AND KEY RESULTS

Herein, we proposed to go deeper into baclofen's mechanism of action and to study its role on the modulation of the immune response after SCI, a major process associated with the severeness of the lesion. Using a SCI compression mice model, we confirmed that baclofen leads to higher locomotor performance, but only at 1 mg·kg-1 and not in higher concentrations, as 5 mg·kg-1. Moreover, we found that baclofen at 1 mg·kg-1 can strongly modulate the immune response after SCI at local, systemic and peripheric levels. This is interesting and intriguingly at the same time, since now, additional studies should be performed to understand if the modulation of the immune response is the responsible for the locomotor outcomes observed on Baclofen treated animals.

CONCLUSION AND IMPLICATIONS

Our findings showed, for the first time, that baclofen can modulate the immune response after SCI, becoming a relevant drug in the field of the immunomodulators.

Cardiovascular and locomotor effects of binary mixtures of common 'bath salts' constituents: Studies with methylone, methylenedioxypyrovalerone and caffeine in rats

BACKGROUND AND PURPOSE

The use of 'bath salts' drug preparations has been associated with high rates of toxicity and death. Preparations often contain mixtures of drugs, including multiple synthetic cathinones or synthetic cathinones and caffeine. Little is known about the interactions of 'bath salts' constituents and adverse effects often reported by users.

EXPERIMENTAL APPROACH

This study used adult male Sprague-Dawley rats to characterise the cardiovascular effects, locomotor effects and pharmacokinetics of methylone, methylenedioxypyrovalerone (MDPV) and caffeine, administered alone and as binary mixtures. Dose-addition analyses were used to determine the effect levels of a strictly additive interaction for dose pairs.

KEY RESULTS

Methylone, MDPV and caffeine increased heart rate (HR) and locomotion, with methylone producing the largest increase in HR, MDPV producing the largest increase in locomotor activity and caffeine being the least effective in stimulating HR and locomotor activity. MDPV and caffeine increased mean arterial pressure (MAP), with caffeine being more effective than MDPV. The nature of the interactions between methylone and MDPV tended towards sub-additivity for all endpoints, whereas interactions between MDPV or methylone and caffeine tended to be additive or sub-additive for cardiovascular endpoints, and additive or supra-additive for increases in locomotion. No pharmacokinetic interactions were observed between individual constituents, but methylone appeared to display nonlinear pharmacokinetics at the largest dose evaluated.

CONCLUSION AND IMPLICATIONS

These findings demonstrate that 'bath salts' preparations can impact both cardiovascular and locomotor effects and suggest that interactions among constituent drugs could contribute to the 'bath salts' toxidrome reported by human users.

Atractylodes macrocephala Koidz polysaccharide ameliorates DSS-induced colitis in mice by regulating the gut microbiota and tryptophan metabolism

BACKGROUND AND PURPOSE

Ulcerative colitis (UC) is an idiopathic inflammatory bowel disease, and the range of current clinical treatments is not ideal. We previously found that polysaccharide of Atractylodes macrocephala Koidz (PAMK) is beneficial in DSS-induced colitis, and we aimed to investigate the underlying mechanisms in this study.

EXPERIMENTAL APPROACH

PAMK was used to treat DSS-induced colitis in mice, 16S rRNA sequencing analysis was used to detect changes in the intestinal microbiota, targeted metabolomics analysis was used to determine the content of tryptophan-metabolizing bacteria, and western blotting was used to determine aryl hydrocarbon receptor (AhR) and pregnane X receptor (PXR) levels. Furthermore, antibiotic-mediated depletion of gut microbiota and faecal microbiota transplantation were performed to assess the role of the gut microbiota in PAMK alleviation of colitis.

KEY RESULTS

PAMK treatment relieved intestinal microbiota dysbiosis in mice with colitis, contributed to the proliferation of tryptophan-metabolizing bacteria, and increased the levels of tryptophan metabolites, resulting in a significant increase in the nuclear translocation of PXR and expression of PXR and its target genes, but not AhR. The gut microbiota is important in PAMK treatment of colitis, including in the alleviation of symptoms, inhibition of inflammation, maintenance of the integrity of the intestinal barrier, and the regulation of the Th17/Treg cell balance.

CONCLUSION AND IMPLICATIONS

Based on our findings, we elucidate a novel mechanism by which PAMK alleviates DSS-induced colitis and thus provides evidence to support the potential development of PAMK as a new clinical drug against UC.

Rescue of loss-of-function long QT syndrome-associated mutations in KV7.1/KCNE1 by the endocannabinoid N-arachidonoyl-L-serine (ARA-S)

BACKGROUND AND PURPOSE

Congenital long QT syndrome (LQTS) involves genetic mutations affecting ion channels, leading to a prolonged QT interval and increased risk of potentially lethal ventricular arrhythmias. Mutations in the genes encoding KV7.1/KCNE1 are the most frequent, with channel loss-of-function contributing to LQTS. The endocannabinoid N-arachidonoyl-L-serine (ARA-S) has been shown to facilitate activation of wild type KV7.1/KCNE1 channels and to counteract a prolonged QT interval in isolated guinea pig hearts. In this study, we examine the ability of ARA-S to facilitate activation of LQTS-associated mutations, in various regions of the channel, and hence to counteract loss-of-function.

EXPERIMENTAL APPROACH

The two-electrode voltage clamp technique on Xenopus oocytes expressing human KV7.1/KCNE1 channels was used to investigate the effects of ARA-S in 20 LQTS type 1-associated mutations distributed across the channel. Thereafter, different electrophysiology was used to assess ARA-S effects in mammalian cells.

KEY RESULTS

ARA-S enhanced the function of all mutated channels by shifting V50 and increasing current amplitude. However, the magnitude of effect varied, related to whether mutations were in one of the two putative ARA-S binding sites on the channel as suggested by molecular dynamics simulations. ARA-S displayed translational potential by facilitating channel opening in mammalian cells and shortening the action potential duration in cardiomyocytes.

CONCLUSIONS AND IMPLICATIONS

This study demonstrates the rescuing capability of ARA-S on a diverse set of LQTS mutants. These insights may aid in developing drug compounds using ARA-S sites and mechanisms and guide interpretation of which LQTS mutants respond well to such compounds.

Targeting CB2 receptor with a novel antagonist reverses cognitive decline, neurodegeneration and pyroptosis in a TAU-dependent frontotemporal dementia mouse model

Frontotemporal dementia (FTD) comprises a group of disorders characterized by a progressive decline in behavior or language linked to the degeneration of the frontal and anterior temporal lobes followed by hippocampal atrophy. There are no effective treatments for FTD and for this reason, novel pharmacological targets, such as the endocannabinoid system (ECS), are being explored. Previous results from our laboratory showed a TAUP301L-dependent increase in CB2 receptor expression in hippocampal neurons of a FTD mouse model, alongside the neuroprotective impact of CB2 ablation. In this study, we evaluated the therapeutic potential of a new CB2 antagonist (PGN36) in our TAU-dependent FTD mouse model. Six-month-old mice received stereotaxic injections of an adeno-associated virus expressing human TAUP301L protein (AAV-TAUP301L) into the right hippocampus and were treated daily with PGN36 (5 mg/kg, i.p.) or vehicle for three weeks. By integrating behavioral tests, RNA-seq, qPCR expression analysis, and immunofluorescence in the AAV expressing TAU mouse model, we found that PGN36 treatment reverses key features of the neurodegenerative process triggered by TAUP301L overexpression. PGN36 treatment effectively countered TAUP301L-induced cognitive decline by reducing TAU protein expression levels and restoring markers of synaptic plasticity. Notably, we observed neuroprotection in the dentate gyrus granular layer, which we attribute to the modulation of pyroptosis. This programmed cell death pathway, is triggered by TAUP301L overexpression. PGN36 appears to modulate the pyroptotic cascade, thereby preventing the pyroptosis-induced neuronal loss. These findings collectively underscore the neuroprotective potential of this novel CB2 antagonist treatment against TAU-associated FTD.

Trilobatin, a Naturally Occurring GPR158 Ligand, Alleviates Depressive-like Behavior by Promoting Mitophagy

The G-protein-coupled receptor (GPR158), an orphan receptor, is highly expressed in the medial prefrontal cortex (mPFC) and identified as a novel therapeutic target for depression. Trilobatin is a naturally occurring food additive with potent neuroprotective properties. However, its pharmacological effects and molecular mechanisms against depression remain unknown. Therefore, we explored whether trilobatin alleviates depression by targeting GPR158. Our results indicated that trilobatin alleviated chronic unpredictable mild stress (CUMS)-induced depressive-like behavior in mice. Mitophagy contributed to the antidepressant-like effect of trilobatin, as evidenced by the qRT-PCR array. Furthermore, trilobatin up-regulated autophagy-associated protein expression, restored mitochondrial dynamic balance, and inhibited oxidative stress of mPFC in mice after CUMS insult and in corticosterone-induced primary neuron injury. Intriguingly, trilobatin directly bound to GPR158 and decreased its level of protein expression. GPR158 deficiency attenuated depressive-like behavior through promoting mitophagy, while the antidepressant effect of trilobatin was strengthened in GPR158-deficient mice. Our findings highlight that GPR158-mediated mitophagy acts as a crucial pharmacological target for depression and reveal a new-found pharmacological property of trilobatin: serving as a novel naturally occurring ligand of GPR158 to safeguard from depression by oxidative stress by promoting mitophagy.

Combined therapy with pirfenidone and nintedanib counteracts fibrotic silicosis in mice

BACKGROUND AND PURPOSE

Pneumoconiosis, especially silicosis, is a prevalent occupational disease with substantial global economic implications and lacks a definitive cure. Both pneumoconiosis and idiopathic pulmonary fibrosis (IPF) are interstitial lung diseases, which share many common physiological characteristics. Because pirfenidone and nintedanib are approved to treat IPF, their potential efficacy as antifibrotic agents in advanced silicosis deserves further exploration. Thus, we aimed to evaluate the individual and combined effects of pirfenidone and nintedanib in treating advanced silicosis mice and elucidate the underlying mechanisms of their therapeutic actions via multiomics.

EXPERIMENTAL APPROACH

We administered monotherapy or combined therapy of pirfenidone and nintedanib, with low and high doses, in silicosis established after 6 weeks and evaluated lung function, inflammatory responses and fibrotic status. Additionally, we employed transcriptomic and metabolomic analyses to uncover the mechanisms underlying different therapeutic strategies.

KEY RESULTS

Both pirfenidone and nintedanib were effective in treating advanced silicosis, with superior outcomes observed in combination therapy. Transcriptomic and metabolomic analyses revealed that pirfenidone and nintedanib primarily exerted their therapeutic effects by modulating immune responses, signalling cascades and metabolic processes involving lipids, nucleotides and carbohydrates. Furthermore, we experimentally validated both monotherapy and combined therapy yielded therapeutic benefits through two common signalling pathways: steroid biosynthesis and purine metabolism.

CONCLUSION AND IMPLICATIONS

In conclusion, pirfenidone and nintedanib, either individually or in combination, demonstrate substantial potential in advanced silicosis. Furthermore, combined therapy outperformed monotherapy, even at low doses. These therapeutic benefits are attributed to their influence on diverse signalling pathways and metabolic processes.

Platinum Deposition in the Central Nervous System: A Novel Insight into Oxaliplatin-induced Peripheral Neuropathy in Young and Old Mice

Numerous factors can contribute to the incidence or exacerbation of peripheral neuropathy induced by oxaliplatin (OXA). Recently, platinum accumulation in the spinal cord of mice after OXA exposure, despite the efficient defenses of the central nervous system, has been demonstrated by our research group, expanding the knowledge about its toxicity. One hypothesis is platinum accumulation in the spinal cord causes oxidative damage to neurons and impairs mitochondrial function. Thus, the main aim of this study was to investigate the relationship between aging and OXA-induced neuropathic pain and its comorbidities, including anxious behavior and cognitive impairment. By using an OXA-induced peripheral neuropathy model, platinum and bioelement concentrations and their influence on oxidative damage, neuroprotection, and neuroplasticity pathways were evaluated in Swiss mice, and our findings showed that treatment with OXA exacerbated pain and anxious behavior, albeit not age-induced cognitive impairment. Platinum deposition in the spinal cord and, for the first time, in the brain of mice exposed to OXA, regardless of age, was identified. We found that alterations in bioelement concentration, oxidative damage, neuroprotection, and neuroplasticity pathways induced by aging contribute to OXA-induced peripheral neuropathy. Our results strive to supply a basis for therapeutic interventions for OXA-induced peripheral neuropathy considering age specificities.

Intrathecal administration of Anti-Nogo-A antibody in macaque monkeys: Pharmacokinetics, tissue penetration and target interaction

Intrathecal drug administration represents a promising method to deliver biologics effectively to the central nervous system (CNS). However, little is known about the tolerability and pharmacokinetics of intrathecally applied antibodies. Hence, the focus of this study was to evaluate the toxicity, pharmacokinetic, and pharmacodynamic properties of an intrathecally administered human monoclonal antibody against the growth inhibitory CNS membrane protein Nogo-A in the non-human primate (NHP). The antibody was repeatedly injected into the lumbar cerebrospinal fluid (CSF) sack of NHPs, Macaca fascicularis (N ​= ​18), at three dose levels (placebo, 75 and 150 ​mg antibody/injection, n ​= ​6/group). CSF and serum samples were collected for pharmacokinetic analysis. The health status was constantly monitored to detect any treatment-related abnormalities. After sacrifice, the CNS tissues were evaluated by immunohistochemistry and biochemistry to study the antibody distribution and target interaction in the spinal cord and brain. No treatment-related side effects were observed, and the treatment was well tolerated by NHPs. After administration, the antibody was rapidly cleared from the CSF with a half-life of 6.4 ​h and accumulated in the serum where it showed a half-life of 13.7 days. The antibody distributed over the spinal cord and brain, penetrated into the CNS parenchyma where it bound to Nogo-A expressing neurons and oligodendrocytes, and induced significant (P ​< ​0.05) downregulation of the target antigen Nogo-A. Collectively, these results support the direct administration of therapeutic antibodies into the CSF and are of relevance for the antibody-based therapeutics currently in development for different CNS diseases.

Human metabolism of the semi-synthetic cannabinoids hexahydrocannabinol, hexahydrocannabiphorol and their acetates using hepatocytes and urine samples

Hexahydrocannabinol (HHC), hexahydrocannabiphorol (HHCP) and their acetates, HHC-O and HHCP-O, respectively, are emerging in Europe as alternatives to tetrahydrocannabinol (THC). This study aimed to elucidate the metabolic pathways of the semi-synthetic cannabinoids HHC, HHCP, HHC-O and HHCP-O from incubation with human hepatocytes. The metabolites of HHC were also identified in authentic urine samples. HHC, HHCP, HHC-O and HHCP-O were incubated with primary human hepatocytes for 1, 3 and 5 h. Authentic urine samples from cases screened positive for cannabis in blood using ELISA but confirmed negative were analysed both non-hydrolysed and hydrolysed for HHC metabolites. Potential metabolites were identified using ultra-high performance liquid chromatography (UHPLC) coupled to a quadrupole time-of-flight mass spectrometer (QToF-MS). HHC and HHCP were primarily metabolised through monohydroxylation (monoOH), followed by oxidation to a carboxylic acid metabolite. HHC-O and HHCP-O were rapidly metabolised to HHC and HHCP, respectively. In authentic urine samples, 18 different metabolites were identified, and 99.3% of hydroxylated metabolites were glucuronidated. 11-OH-HHC, 5'OH-HHC and another metabolite with a monoOH on the side chain were the only metabolites present in all 16 urine samples. The metabolism of HHC and HHCP were similar, although the longer alkyl side chain of HHCP (heptyl) led to greater hydroxylation on the side chain than HHC (pentyl). The use of HHC and HHCP can be differentiated from the use of THC and other phytocannabinoids, but the use of the acetate analogues may not be differentiable from their non-acetate analogues.

Synergistic-like decreases in alcohol intake following combined pharmacotherapy with GLP-1 and amylin in male rats

BACKGROUND AND PURPOSE

The limited effectiveness of current pharmacological treatments for alcohol use disorder (AUD) highlights the need for novel therapies. These may involve the glucagon-like peptide-1 receptor or the amylin receptor, as treatment with agonists targeting either of these receptors lowers alcohol intake. The complexity of the mechanisms underlying AUD indicates that combining agents could enhance treatment efficacy. While a combination of amylin receptor and GLP-1 receptor agonists reduced food intake and body weight synergistic-like, its influence on alcohol intake is unknown.

EXPERIMENTAL APPROACH

Effects of a range of dose-combinations of GLP-1 receptor (dulaglutide) and amylin receptor (salmon calcitonin; sCT) agonists on alcohol intake were explored in male and female rats. We used dose combinations that either lowered alcohol intake as monotherapy (0.1 mg·kg-1 + 5 μg·kg-1), or that did not affect alcohol consumption per se (0.075 mg·kg-1 + 2 μg·kg-1).

KEY RESULTS

Acute administration of dulaglutide and sCT (0.1 mg·kg-1 + 5 μg·kg-1) reduced alcohol intake in males, but not in females. When higher doses were evaluated in female rats, a decrease in alcohol intake was observed. Furthermore, the low dose combination (0.075 mg·kg-1 + 2 μg·kg-1) decreased, in in a synergistic-like manner, alcohol intake and prevented abstinence-induced drinking without affecting kaolin intake in males. However, tolerance developed during sub-chronic treatment.

CONCLUSION AND IMPLICATIONS

Collectively, these findings show that the combination of dulaglutide and sCT decreased, in in a synergistic-like manner, alcohol consumption in male rats. Contrarily, higher doses are required for females.

A synthetic peptide, derived from neurotoxin GsMTx4, acts as a non-opioid analgesic to alleviate mechanical and neuropathic pain through the TRPV4 channel

Mechanical pain is one of the most common causes of clinical pain, but there remains a lack of effective treatment for debilitating mechanical and chronic forms of neuropathic pain. Recently, neurotoxin GsMTx4, a selective mechanosensitive (MS) channel inhibitor, has been found to be effective, while the underlying mechanism remains elusive. Here, with multiple rodent pain models, we demonstrated that a GsMTx4-based 17-residue peptide, which we call P10581, was able to reduce mechanical hyperalgesia and neuropathic pain. The analgesic effects of P10581 can be as strong as morphine but is not toxic in animal models. The anti-hyperalgesic effect of the peptide was resistant to naloxone (an μ-opioid receptor antagonist) and showed no side effects of morphine, including tolerance, motor impairment, and conditioned place preference. Pharmacological inhibition of TRPV4 by P10581 in a heterogeneous expression system, combined with the use of Trpv4 knockout mice indicates that TRPV4 channels may act as the potential target for the analgesic effect of P10581. Our study identified a potential drug for curing mechanical pain and exposed its mechanism.

Nitazoxanide protects against heart failure with preserved ejection and metabolic syndrome induced by high-fat diet (HFD) plus L-NAME "two-hit" in mice

The clinical antiprotozoal drug nitazoxanide has been demonstrated to improve the experimental diabetes mellitus, lipid metabolism disorders, atherosclerosis and inhibit inflammation. Since the pathogenesis of heart failure with preserved ejection (HFpEF) is multifactorial and closely associated with the aforementioned diseases, we aim to study the effect of nitazoxanide on high-fat diet (HFD) plus L-NAME (N ω-nitro-l-arginine methyl ester)-induced HFpEF and metabolic syndrome in mice. We found that oral nitazoxanide improved cardiac hypertrophy, cardiac fibrosis, cardiac diastolic dysfunction, increased blood pressure, impaired exercise tolerance, impaired glucose handling, serum lipid disorders, hepatic steatosis, increased weight of white adipose tissues and kidney fibrosis in HFD + L-NAME-treated mice. In the established HFD + L-NAME-induced HFpEF and metabolic syndrome mouse model, therapeutic treatment with nitazoxanide rescued HFD + L-NAME-induced pathological phenotypes as mentioned above. The in vitro experiments revealed that tizoxanide, the active metabolite of nitazoxanide, increased the basal mitochondria metabolism of cardiomyocytes, inhibited cardiomyocyte hypertrophy and collagen secretion from cardiac fibroblasts, and relaxed phenylephrine- and U46619-induced constriction of rat mesenteric arteries, indicating that the direct effect of tizoxanide might partly contribute to the protective effect of nitazoxanide against HFpEF in vivo. The present study suggests that nitazoxanide might be a potential drug for HFpEF and metabolic syndrome therapy.

Anti-b diminishes hyperlipidaemia and hepatic steatosis in hamsters and mice by suppressing the mTOR/PPARγ and mTOR/SREBP1 signalling pathways

BACKGROUND AND PURPOSE

As a chronic metabolic syndrome, hyperlipidaemia is manifested as aberrantly elevated cholesterol and triglyceride (TG) levels, primarily attributed to disorders in lipid metabolism. Despite the promising outlook for hyperlipidaemia treatment, the need persists for the development of lipid-lowering agents with heightened efficiency and minimal toxicity. This investigation aims to elucidate the lipid-lowering effects and potential pharmacodynamic mechanisms of Anti-b, a novel low MW compound.

EXPERIMENTAL APPROACH

We employed high-fat diet (HFD) in hamsters and mice or oleic acid (OA) in cultures of HepG2 cells and LO2 cells to induce hyperlipidaemia models. We administered Anti-b to assess its therapeutic effects on dyslipidaemia and hepatic steatosis. We used western blotting, RNA sequencing, GO and KEGG analysis, oil red O staining, along with molecular docking and molecular dynamics simulation to elucidate the mechanisms underlying the effects of Anti-b.

KEY RESULTS

Anti-b exhibited a substantial reduction in HFD-induced elevation of blood lipids, liver weight to body weight ratio, liver diameter and hepatic fat accumulation. Moreover, Anti-b demonstrated therapeutic effects in alleviating total cholesterol (TC), TG levels, and lipid accumulation derived from OA in HepG2 cells and LO2 cells. Mechanistically, Anti-b selectively bound to the mTOR kinase protein and increased mTOR thermal stability, resulting in downregulation of phosphorylation level. Notably, Anti-b exerted anti-hyperlipidaemia effects by modulating PPARγ and SREBP1 signalling pathways and reducing the expression level of mSREBP1 and PPARγ proteins.

CONCLUSION AND IMPLICATIONS

In conclusion, our study has provided initial data of a novel low MW compound, Anti-b, designed and synthesised to target mTOR protein directly. Our results indicate that Anti-b may represent a novel class of drugs for the treatment of hyperlipidemia and hepatic steatosis.

Lactate-triggered histone lactylation contributes to podocyte epithelial-mesenchymal transition in diabetic nephropathy in mice

Diabetic nephropathy (DN) closely relates to morphological and functional changes of podocytes, and anaerobic glycolysis represents the predominant energy source of podocytes. However, it is unknown whether lactate accumulation in chronic high glucose causes epithelial-mesenchymal transition (EMT) of podocytes through lactate-derived histone lysine lactylation (HKla). Lactate levels increased in high glucose-stimulated mouse podocyte cell line MPC and blood and the kidney of diabetic mice. High glucose or exogenous lactate decreased nephrin levels while increased collagen IV and HKla levels in MPC, but co-treatment with oxamate or dichloroacetate reduced lactate levels and alleviated the decreases in nephrin and zonula occludens- 1 levels and the increases in collagen IV and α-smooth muscle actin as well as HKla levels in high glucose-cultured MPC. However, co-treatment with rotenone diversely affected these indices. Eleven intersection genes were screened in lactate raising and lowering interventions in podocytes using RNA sequencing and four genes were validated by qPCR. Furthermore, lactate-lowering treatments attenuated renal functions, EMT, and histone lactylation in the kidney of diabetic mice. Additionally, the increased lactate might result from the upregulated monocarboxylate transporter 2 in the mitochondria and the decreased pyruvate dehydrogenase activity. Together, we reveal the role of histone lactylation in driving the EMT phenotype of podocytes in chronic high glucose state, subsequently promoting the pathological process of DN. Our study provides a reference for the study of the relationship between lactate-induced histone lactylation modification and diabetic complications.

Bilateral transcranial direct-current stimulation confers neuroprotection through suppression of PKM2 after mouse cerebral ischemia injury

BACKGROUND

In its tetrameric form, pyruvate kinase M2 isoform (PKM2) catalyzes the last step of glycolysis and plays a key role in the metabolic reprogramming via regulating the signaling of pentose phosphate pathway (PPP). But the role of PKM2 in cerebral ischemia-reperfusion (I/R) injury remains unknown.

METHODS

Mice model of middle cerebral artery occlusion (MCAO) and model of oxygen-glucose deprivation (OGD) injury in cultured neurons were established. PKM2 activator or inhibitor were used to test the effects of PKM2 in wild-type and PKM2 (-/-) mice after I/R injury. Biochemical and molecular approach were used to detect the level of PKM2 tetramers and PPP metabolites.

RESULTS

We showed for the first time that ischemia-induced increase of PKM2 activity promoted neuronal death via the suppression of PPP-dependent antioxidant capacity. To identify therapeutic approach that suppresses ischemia-induced increase of PKM2 activity, we tested the effect of bilateral transcranial direct-current stimulation (BtDCS), a newly established BtDCS approach by us, on PKM2 activity after mouse I/R. Our data demonstrated that BtDCS inhibited PKM2 activity in the ischemic neurons. BtDCS also reduced the cerebral infarct volume and the neurological deficits in stroke mice. We found that BtDCS-induced neuroprotection was mediated through the suppression of PKM2 activity after I/R.

CONCLUSIONS

Together, this study provided novel evidence that supported PKM2 as a crucial regulator of neuronal metabolism after cerebral I/R injury, and revealed the molecular mechanism by which BtDCS protects against mouse cerebral I/R injury through regulating PKM2-mediated metabolic reprogramming.

The expression of contextual fear conditioning involves the dorsal hippocampus TRPV1 receptor interacting with the NMDA/NO/cGMP signalling pathway

BACKGROUND AND PURPOSE

The dorsal hippocampus (dHIP) is pivotal for learning, memory, and defensive responses. Transient receptor potential vanilloid type 1 (TRPV1) receptors in the dHIP modulate contextual fear conditioning by triggering a cascade involving glutamate release, nitric oxide (NO) formation and cyclic guanosine monophosphate (cGMP) production. The present study investigated the involvement of dHIP TRPV1 receptors and their interaction with the glutamate/NO/cGMP signalling pathway in modulating the expression of contextual fear conditioning (CFC).

EXPERIMENTAL APPROACH

Male Wistar rats were submitted to an aversive contextual conditioning session and, 48 h later, were re-introduced to the same aversive environment where the freezing response and autonomic activity (evidenced by increased arterial pressure and heart rate and a decrease in tail temperature) were measured.

KEY RESULTS

The results demonstrated that the TRPV1 antagonist 6-I-CPS in dHIP reduced the expression of CFC, whereas the agonist capsaicin had the opposite effect. Furthermore, dHIP pre-treatment with an NMDA receptor antagonist (AP7), neuronal NO synthase inhibitor (N-propyl-L-arginine), NO scavenger (c-PTIO) or guanylate cyclase inhibitor (ODQ) attenuated capsaicin-induced increases in CFC. Finally, we observed that re-exposure to the aversive chamber increased dHIP NO levels in conditioned animals compared with a non-conditioned group, which was prevented by the administration of the TRPV1 antagonist, 6-I-CPS.

CONCLUSION AND IMPLICATIONS

Our study revealed that TRPV1 receptors in the dHIP play a crucial role in modulating contextual fear expression by acting through the NMDA receptor/NO/cGMP signalling pathway, providing important insights into the underlying mechanisms and potential therapeutic avenues associated with these pathways.

tiRNA-Gly-GCC-002 promotes epithelial-mesenchymal transition and fibrosis in lupus nephritis via FKBP5-mediated activation of Smad

BACKGROUND AND PURPOSE

Renal interstitial fibrosis is a frequent pathological manifestation of lupus nephritis (LN). tRNA halves (tiRNAs) are acquired from tRNA-derived small non-coding RNAs (sncRNAs) and are associated with fibrosis. Our previous study indicated enhanced tiRNA-Gly-GCC-002 (tiRNA002) levels in kidneys were positively related to LN-related fibrosis. However, the precise molecular mechanism remains unclear.

EXPERIMENTAL APPROACH

The mimic and agomiR of tiRNA002 were introduced into tubular epithelial cells (TECs) and MRL/lpr mice by transfection. The levels of gene and protein expressions were quantified using real-time quantitative polymerase chain reaction (RT-qPCR), Western blot and immunofluorescence assays.

KEY RESULTS

In TECs treated with LN serum, as well as in the kidneys of MRL/lpr mice, high levels of tiRNA002 directly influenced the epithelial-mesenchymal transition (EMT) and extracellular matrix (ECM) deposition. Furthermore, tiRNA002 overexpression promoted EMT in TECs and accelerated renal interstitial fibrosis in MRL/lpr mice via Smad signalling. The target gene of tiRNA002, FKBP prolyl isomerase 5 (FKBP5), improved Smad signalling by interacting with phosphorylated Smad2/3. Silencing FKBP5 alleviated LN serum- or tiRNA002-mimic-induced EMT in TECs. In addition, FKBP5 overexpression reversed the tiRNA002 knockdown-mediated reduction of EMT and ECM accumulation.

CONCLUSIONS AND IMPLICATIONS

These findings indicated that tiRNA002 is markedly increased in LN, which facilitates renal fibrosis by promoting EMT via FKBP5-mediated Smad signalling. Therefore, targeting tiRNA002 may be an innovative approach to treat renal interstitial fibrosis in LN.

Unraveling morphine tolerance: CCL2 induces spinal cord apoptosis via inhibition of Nrf2 signaling pathway and PGC-1α-mediated mitochondrial biogenesis

BACKGROUND

Morphine effectively relieves severe pain but leads to analgesic tolerance with long-term use.The molecular mechanisms underlying morphine tolerance remain incompletely understood. Existing literature suggests that chemokine CCL2, present in the spinal cord, plays a role in central nervous system inflammation, including neuropathic pain. Nevertheless, the precise mechanism through which CCL2 mediates morphine tolerance has yet to be elucidated. Consequently, this study aims to investigate the molecular pathways by which CCL2 contributes to the development of morphine analgesic tolerance.

METHODS

Rats were administered intrathecal morphine (10 μg/5 μl) twice a day for seven consecutive days to induce a model of morphine nociceptive tolerance. Western blotting and quantitative real-time polymerase chain reaction (qRT-PCR) were used to detect the expression levels of CCL2 and its related mechanism molecules. Immunofluorescence was used to detect the localization of CCL2 in the spinal cord. Intrathecal injections of inhibitors or agonists to artificially regulate the expression of relevant molecules. The thermal tail-flick experiment was performed to evaluate morphine tolerance in rats.

RESULTS

Morphine-induced CCL2 expression was significantly increased in spinal cord, while conversely, the expressions of Nrf2 and PGC-1a were downregulated. Immunofluorescence showed that the enhanced immune response of CCL2 mainly co-localized with neurons. In vivo, we confirmed that intrathecally injection of CCL2 inhibitor Bindarit could effectively alleviate the occurrence of apoptosis and alleviate morphine tolerance. Similarly, pretreatment with Nrf2 signaling pathway agonist Oltipraz and PGC-1α agonist ZLN005 also achieved similar results, respectively. ROS Fluorescence Assay Kit indicated that increasing the expression of PGC-1α could alleviate the occurrence of apoptosis by reducing the level of ROS.

CONCLUSION

Our data emphasize that chemokine CCL2 inhibited the Nrf2 signaling pathway and PGC-1α-mediated mitochondrial biogenesis, alleviating the occurrence of apoptosis in spinal cord, thereby participating in morphine tolerance. This may provide new targets for the treatment of morphine tolerance.

A pH-sensitive opioid does not exhibit analgesic tolerance in a mouse model of colonic inflammation

BACKGROUND AND PURPOSE

Tolerance to the analgesic effects of opioids and resultant dose escalation is associated with worsening of side effects and greater addiction risk. Here, we compare the development of tolerance to the conventional opioid fentanyl with a novel pH-sensitive μ-opioid receptor (MOR) agonist, (±)-N-(3-fluoro-1-phenethylpiperidine-4-yl)-N-phenyl propionamide (NFEPP) that is active only in acidic inflammatory microenvironments.

EXPERIMENTAL APPROACH

An opioid tolerance model was developed in male C57BL/6 mice, with and without dextran sulphate sodium colitis, using increasing doses of either fentanyl or NFEPP over 5 days. Visceral nociception was assessed in vivo by measuring visceromotor responses (VMRs) to noxious colorectal distensions and in vitro measuring colonic afferent nerve activity of mesenteric nerves and performing patch-clamp recordings from isolated dorsal root ganglia neurons. Somatic thermal nociception was tested using a tail immersion assay. Cardiorespiratory effects were analysed by pulse oximeter experiments.

KEY RESULTS

VMRs and tail immersion tests demonstrated tolerance to fentanyl, but not to NFEPP in colitis mice. Cross-tolerance also occurred to fentanyl, but not to NFEPP. The MOR agonist DAMGO inhibited colonic afferent nerve activity in colitis mice exposed to chronic NFEPP, but not those from fentanyl-treated mice. Similarly, in patch-clamp recordings from isolated dorsal root ganglia neurons, DAMGO inhibited neurons from NFEPP-, but not fentanyl-treated mice.

CONCLUSION AND IMPLICATIONS

NFEPP did not exhibit tolerance in an inflammatory pain model, unlike fentanyl. Consequently, dose escalation to maintain analgesia during an evolving inflammation could be avoided, mitigating the potential risk of side effects.

Early transtympanic administration of rhBDNF exerts a multifaceted neuroprotective effect against cisplatin-induced hearing loss

BACKGROUND AND PURPOSE

Cisplatin-induced sensorineural hearing loss is a significant clinical challenge. Although the potential effects of brain-derived neurotrophic factor (BDNF) have previously been investigated in some ototoxicity models, its efficacy in cisplatin-induced hearing loss remains uncertain. This study aimed to investigate the therapeutic potential of recombinant human BDNF (rhBDNF) in protecting cells against cisplatin-induced ototoxicity.

EXPERIMENTAL APPROACH

Using an in vivo model of cisplatin-induced hearing loss, we investigated the beneficial effects of transtympanic administration of rhBDNF in a thermogel solution on hearing function and cochlear injury, using electrophysiological, morphological, immunofluorescence and molecular analyses.

KEY RESULTS

Our data showed that local rhBDNF treatment counteracted hearing loss in rats receiving cisplatin by preserving synaptic connections in the cochlear epithelium and protecting hair cells (HCs) and spiral ganglion neurons (SGNs) against cisplatin-induced cell death. Specifically, rhBDNF maintains the balance of its receptor levels (pTrkB and p75), boosting TrkB-CREB pro-survival signalling and reducing caspase 3-dependent apoptosis in the cochlea. Additionally, it activates antioxidant mechanisms while inhibiting inflammation and promoting vascular repair.

CONCLUSION AND IMPLICATIONS

Collectively, we demonstrated that early transtympanic treatment with rhBDNF plays a multifaceted protective role against cisplatin-induced ototoxicity, thus holding promise as a novel potential approach to preserve hearing in adult and paediatric patients undergoing cisplatin-based chemotherapy.

Mu-opioid receptors in tachykinin-1-positive cells mediate the respiratory and antinociceptive effects of the opioid fentanyl

BACKGROUND AND PURPOSE

Opioid drugs are potent analgesics that carry the risk of respiratory side effects due to actions on μ-opioid receptors (MORs) in brainstem regions that control respiration. Substance P is encoded by the Tac1 gene and is expressed in neurons regulating breathing, nociception, and locomotion. Tac1-positive cells also express MORs in brainstem regions mediating opioid-induced respiratory depression. We determined the role of Tac1-positive cells in mediating the respiratory effects of opioid drugs.

EXPERIMENTAL APPROACH

In situ hybridization was used to determine Oprm1 mRNA expression (gene encoding MORs) in Tac1-positive cells in regions regulating respiratory depression by opioid drugs. Conditional knockout mice lacking functional MORs in Tac1-positive cells were produced and the respiratory and locomotor responses to the opioid analgesic fentanyl were assessed using whole-body plethysmography. A tail immersion assay was used to assess the antinociceptive response to fentanyl.

KEY RESULTS

Oprm1 mRNA was highly expressed (>80%) in subpopulations of Tac1-positive cells in the preBötzinger Complex, nucleus tractus solitarius, and Kölliker-Fuse/lateral parabrachial region. Conditionally knocking out MORs in Tac1-positive cells abolished the effects of fentanyl on respiratory rate, relative tidal volume, and relative minute ventilation compared with control mice. Importantly, the antinociceptive response of fentanyl was eliminated in mice lacking functional MORs in Tac1-positive cells, whereas locomotor effects induced by fentanyl were preserved.

CONCLUSIONS AND IMPLICATIONS

Our findings suggest that Tac1-positive cells mediate the respiratory depressive and antinociceptive effects of the opioid fentanyl, providing important insights for the development of pain therapies with reduced risk of respiratory side effects.

Slow dissociation kinetics of fentanyls and nitazenes correlates with reduced sensitivity to naloxone reversal at the μ-opioid receptor

BACKGROUND AND PURPOSE

Fentanyls and nitazenes are μ-opioid receptor agonists responsible for a large number of opioid overdose deaths. Here, we determined the potency, dissociation kinetics and antagonism by naloxone at the μ receptor of several fentanyl and nitazene analogues, compared to morphine and DAMGO.

EXPERIMENTAL APPROACH

In vitro assays of G protein activation and signalling and arrestin recruitment were performed. AtT20 cells expressing μ receptors were loaded with a membrane potential dye and changes in fluorescence used to determine agonist potency, dissociation kinetics and susceptibility to antagonism by naloxone. BRET experiments were undertaken in HEK293T cells expressing μ receptors to assess Gi protein activation and β-arrestin 2 recruitment.

KEY RESULTS

The apparent rate of agonist dissociation from the μ receptor varied: morphine, DAMGO, alfentanil and fentanyl dissociated rapidly, whereas isotonitazene, etonitazene, ohmefentanyl and carfentanil dissociated slowly. Slowly dissociating agonists were more resistant to antagonism by naloxone. For carfentanil, the slow apparent rate of dissociation was not because of G protein receptor kinase-mediated arrestin recruitment as its apparent rate of dissociation was not increased by inhibition of G protein-coupled receptor kinases (GRKs) with Compound 101. The in vitro relative potencies of fentanyls and nitazenes compared to morphine were much lower than that previously observed in in vivo experiments.

CONCLUSIONS AND IMPLICATIONS

With fentanyls and nitazenes that slowly dissociate from the μ receptor, antagonism by naloxone is pseudo-competitive. In overdoses involving fentanyls and nitazenes, higher doses of naloxone may be required for reversal than those normally used to reverse heroin overdose.

RIPK1 expression and inhibition in tauopathies: implications for neuroinflammation and neuroprotection

Tauopathies are a group of neurodegenerative diseases characterized by the alteration/aggregation of TAU protein. One of the main challenges of these diseases is that they have neither biomarkers nor pharmacological targets to stop the neurodegenerative process. Apart from the neurodegenerative process, tauopathies are also characterized by a chronic low-grade neuroinflammation process, where the receptor-interacting protein kinase 1 (RIPK1) protein plays an essential role. Our research aimed to explore the role of RIPK1 in various tauopathies. We examined mouse models of frontotemporal dementia (FTD), as well as brain tissue samples from patients with progressive supranuclear palsy (PSP), a primary form of 4R tauopathy, and Alzheimer's disease (AD), which is considered a secondary tauopathy. Our findings show elevated levels of RIPK1 mRNA levels across various forms of tauopathies, in both mouse models and human tissue samples associated with primary and secondary TAU-related disorders. Furthermore, we investigated the potential of using a RIPK1 inhibitor, known as GSK2982772, in a mouse model as a novel treatment strategy for FTD. The data showed that GSK2982772 treatment effectively reduced the reactive astrocyte response triggered by TAUP301L overexpression. However, this RIPK1 inhibitor failed to protect against the neurodegeneration caused by elevated TAUP301L levels in the hippocampal region. These results suggest that although inhibiting RIPK1 activity may help reduce TAU-related astrogliosis in the brain, the complexity of the inflammatory pathways involved could explain the absence of neuroprotective effects against TAU-induced neurodegeneration.

A Standardized Extract of Zingiber officinale Roscoe Regulates Clinical and Biological Outcomes in Two Different EAE Mouse Models

Background/Objectives: Multiple sclerosis (MS) is a chronic inflammatory disease of the central nervous system characterized by demyelination and neuronal damage. Current MS therapies are unsatisfactory, and new therapies are encouraged. A correlation between nutritional intake and MS has been speculated. Supplementation of approved immunomodulatory therapy with herbal medicines possessing antioxidant and anti-inflammatory activities could provide benefits to MS patients. Ginger is one of the most widely consumed dietary supplements in the world, commonly used in traditional medicine. Studies demonstrated that ginger may also be beneficial in the management of neurodegenerative diseases. The aim of this study is to investigate the MS therapeutic potential of ginger. Methods: A standardized Zingiber officinale Roscoe extract (ZOE) was orally administered for 14 days. Two experimental autoimmune encephalomyelitis (EAE) models in mice were used. The PLP139-151-EAE relapsing-remitting model and MOG35-55-EAE chronic model. Clinical score, von Frey, hot plate, and rotarod tests were used for behavioral tests. ELISA and Western blotting were used to measure cytokines levels. Evans Blue content was determined spectrophotometrically. Results: ZOE attenuated motor disability and pain hypersensitivity in both models had no effect on body weight loss. ZOE reduced the blood-brain barrier (BBB) permeability in the PLP-EAE models and reduced levels of circulating cytokines (Il-6, IL-17) in the MOG-EAE model. ZOE attenuated spinal cytokines overexpression in both models. Conclusions: ZOE improves EAE symptoms and attenuates the proinflammatory response in both models, representing a promising nutraceutical support to the conventional therapeutic approach to MS.

Characterizing the therapeutical use of ketamine for adolescent rats of both sexes: Antidepressant-like efficacy and safety profile

While ketamine was approved for treatment-resistant depression in adult patients, its efficacy and safety profile for adolescence still requires further characterization. In this context, prior preclinical studies have shown that sub-anesthetic doses of ketamine during adolescence exert antidepressant-like effects in rodents in a dose- and sex-dependent manner. However, additional studies evaluating the short- and long-term safety profile of ketamine at the doses necessary to induce antidepressant-like effects are needed. The present study aimed at validating the dose- and sex-dependent antidepressant-like responses of adolescent ketamine while evaluated its safety profile in rats of both sexes. To do so, ketamine was administered (1, 5 or 10 mg/kg; vs. vehicle; 1 vs. 7 days) during adolescence in naïve or early-life stressed (i.e., maternal deprivation) rats of both sexes. Antidepressant-like responses were scored in the forced-swim or novelty-suppressed feeding tests, and safety was evaluated by measuring psychomotor- and reinforcing-like responses induced by ketamine. In addition, long-term safety was assessed in adulthood through cognitive performance, or addiction liability (induced by ketamine re-exposure in rats treated with ketamine in adolescence). The main results validated the potential use of ketamine as an antidepressant for adolescence, but at different dose ranges for each sex. However, some safety concerns emerged in adolescent female rats (i.e., signs of sensitization at the dose used as antidepressant) or adult male rats (i.e., addiction liability when re-exposed to ketamine in adulthood), suggesting that caution and further research are needed before ketamine could be safely used in the clinic as an antidepressant for adolescents.

Discovery of E0199: A novel compound targeting both peripheral NaV and KV7 channels to alleviate neuropathic pain

This research study focuses on addressing the limitations of current neuropathic pain (NP) treatments by developing a novel dual-target modulator, E0199, targeting both NaV1.7, NaV1.8, and NaV1.9 and KV7 channels, a crucial regulator in controlling NP symptoms. The objective of the study was to synthesize a compound capable of modulating these channels to alleviate NP. Through an experimental design involving both in vitro and in vivo methods, E0199 was tested for its efficacy on ion channels and its therapeutic potential in a chronic constriction injury (CCI) mouse model. The results demonstrated that E0199 significantly inhibited NaV1.7, NaV1.8, and NaV1.9 channels with a particularly low half maximal inhibitory concentration (IC50) for NaV1.9 by promoting sodium channel inactivation, and also effectively increased KV7.2/7.3, KV7.2, and KV7.5 channels, excluding KV7.1 by promoting potassium channel activation. This dual action significantly reduced the excitability of dorsal root ganglion neurons and alleviated pain hypersensitivity in mice at low doses, indicating a potent analgesic effect without affecting heart and skeletal muscle ion channels critically. The safety of E0199 was supported by neurobehavioral evaluations. Conclusively, E0199 represents a ground-breaking approach in NP treatment, showcasing the potential of dual-target small-molecule compounds in providing a more effective and safe therapeutic option for NP. This study introduces a promising direction for the future development of NP therapeutics.

Characterization of novel nitazene recreational drugs: Insights into their risk potential from in vitro µ-opioid receptor assays and in vivo behavioral studies in mice

2-Benzylbenzimidazole derivatives or 'nitazenes' are increasingly present on the recreational drug market. Here, we report the synthesis and pharmacological characterization of 15 structurally diverse nitazenes that might be predicted to emerge or grow in popularity. This work expands the existing knowledge about 2-benzylbenzimidazole structure-activity relationships (SARs), while also helping stakeholders (e.g., forensic toxicologists, clinicians, policymakers) in their risk assessment and preparedness for the potential next generation of nitazenes. In vitro µ-opioid receptor (MOR) affinity was determined via competition radioligand (3[H]DAMGO) binding assays in rat brain tissue. MOR activation (potency and efficacy) was studied by means of a cell-based β-arrestin 2 recruitment assay. For seven nitazenes, including etonitazene, opioid-like pharmacodynamic effects (antinociception, locomotor activity, body temperature changes) were evaluated after subcutaneous administration in male C57BL/6 J mice. The results showed that all nitazenes bound to MOR with nanomolar affinities, and the functional potency of several of them was comparable to or exceeded that of fentanyl. In vivo, dose-dependent effects were observed for antinociception, locomotor activity, and body temperature changes in mice. SAR insights included the high opioid-like activity of methionitazene, iso-butonitazene, sec-butonitazene, and the etonitazene analogues 1-ethyl-pyrrolidinylmethyl N-desalkyl etonitazene and ethylene etonitazene. The most potent analogue of the panel across all functional assays was α'-methyl etonitazene. Taken together, through critical pharmacological evaluation, this work provides a framework for strengthened preparedness and risk assessments of current and future nitazenes that have the potential to cause harm to users.

Interaction between fluticasone furoate and umeclidinium in passively sensitized isolated human airways

Asthma management often includes inhaled corticosteroids (ICSs), with additional controllers like long-acting muscarinic antagonists (LAMAs) for severe cases. The primary goal of this study was to investigate the pharmacological interaction between various concentrations of fluticasone furoate (FF) and umeclidinium (UME) in isolated human airways to determine the nature of their interaction, whether synergistic or additive. Medium bronchi and small airways obtained from patients undergoing lobectomy were passively sensitized to mimic asthmatic conditions. The effects of FF and UME, alone and in combination, on airway relaxation were evaluated using histamine-induced contraction and electrical field stimulation. Pharmacological interactions were analyzed using the Bliss Independence theory. Results indicated that FF induced a partial, concentration-dependent relaxation of sensitized airways, while UME induced a larger relaxation in medium bronchi but a weaker effect in small airways. The combination of FF and UME resulted in significantly greater relaxation than either drug alone, demonstrating synergism at high concentrations in medium bronchi but only additive effects in small airways. This study suggests that higher doses of FF might be necessary in a fixed dose combination to achieve optimal synergistic bronchodilation with UME. Future research should focus on clinical trials to confirm these findings and explore the molecular mechanisms underlying these interactions, potentially improving personalized asthma therapy.

Sex differences in the metabolic activation of and platelet response to vicagrel in mice: Androgen as a key player

As a biological variable, sex influences the metabolism of and/or response to certain drugs. Vicagrel is being developed as an investigational new drug in China; however, it is unknown whether sex could affect its metabolic activation and platelet responsiveness. This study aimed to determine whether such differences could exist, and to elucidate the mechanisms involved. Orchiectomized (ORX) or ovariectomized (OVX) mouse models were used to investigate the effects of androgens or estrogens on the metabolic activation of and platelet response to vicagrel. Plasma vicagrel active metabolite H4 concentrations, platelet inhibition of vicagrel, and protein levels of intestinal hydrolases Aadac and Ces2 were measured, respectively. Further, p38-MAPK signaling pathway was enriched, whose role was determined using SB202190. Results showed that female mice exhibited significantly elevated systemic exposure of H4 and enhanced platelet responses to vicagrel than males, and that protein expression levels of Aadac and Ces2 differed by sex. OVX mice exhibited less changes than sham mice. ORX mice exhibited increases in protein levels of intestinal hydrolases, systemic exposure of H4, and platelet inhibition of vicagrel, but dihydrotestosterone (DHT) reversed these changes in ORX mice and suppressed these changes in OVX mice. Phosphorylated p38 levels were reduced in female or ORX mice but increased in ORX mice by DHT. SB202190 reversed DHT-induced changes observed in ORX mice. We concluded that sex differences exist in metabolic activation of and platelet response to vicagrel in mice through elevation of p38 phosphorylation by androgens, suggesting sex-based vicagrel dosage adjustments for patient care.

Pharmacological characterization of prostaglandin E2 EP2 and EP4 receptors in male rat locus coeruleus neurons ex vivo

The inflammatory mediator prostaglandin E2 (PGE2) binds to Gs-coupled EP2 and EP4 receptors. These receptors are located in the locus coeruleus (LC), the principal noradrenergic nucleus in the brain, but their functional role remains unknown. In this study, the PGE2 EP2 and EP4 receptors in LC cells from male rat brain slices were pharmacologically characterized by single-unit extracellular electrophysiology. The EP2 receptor agonists butaprost (0.01-10 μM) and treprostinil (0.03-10 µM) and the EP4 receptor agonists rivenprost (0.01 nM-1 µM) and TCS2510 (0.20 nM-2 µM) increased the firing rate of LC neurons in a concentration-dependent manner. The EP2 receptor antagonist PF-04418948 (10 nM) hindered the excitatory effect of butaprost and treprostinil while the EP4 receptor antagonist L-161,982 (30 and 300 nM) blocked the excitatory effect caused by rivenprost and TCS2510. The effects of butaprost and rivenprost were prevented by extracellular sodium replacement but were not modified by the protein kinase A (PKA) activator 8-Br-cAMP (1 mM) or the inhibitor H-89 (10 μM). However, the Gβγ subunit blocker gallein (20 μM) hindered the stimulatory effect of butaprost while the Gαs subunit inhibitor NF449 (10 µM) prevented that of rivenprost. Finally, rivenprost-induced stimulation (30 nM) was not occluded by butaprost (1 µM). In conclusion, activation of EP2 and EP4 receptors excites LC noradrenergic neurons through sodium-dependent currents via different G protein subunits in male rat brain slices. EP2 and EP4 in the LC may constitute pharmacological targets for the treatment of pain, fever, drug addiction, anxiety and neuroinflammatory diseases.

Antinociceptive Effects of α2/α3-Subtype-Selective GABAA Receptor Positive Allosteric Modulators KRM-II-81 and NS16085 in Male Rats: Behavioral Specificity

Recent studies suggest that among the gamma-aminobutyric acid type A (GABAA)receptor subtype heterogeneity, α2/α3 subunits of GABAA receptors mediate pain processing. Therefore, α2/α3 subtype-selective GABAA receptor-positive allosteric modulators (PAMs) may be candidate analgesics. Antinociceptive effects of α2/α3 subtype-selective GABAA receptor PAMs have been reported, but the behavioral effects of these compounds have not been systematically evaluated. This study examined the behavioral effects of two α2/α3 subtype-selective GABAA receptor PAMs, KRM-II-81 and NS16085, in male rats. The antinociceptive effects of KRM-II-81 and NS16085 were examined using rat models of inflammatory (complete Freund's adjuvant) and neuropathic pain (chronic constriction injury). The effect of KRM-II-81 on affective pain was measured using the place escape/avoidance paradigm (PEAP). Rate-response of food-maintained operant responding, horizontal wire test, and the spontaneous alternation T-maze were assessed to study the side-effect profiles of KRM-II-81 and NS16085. The benzodiazepine midazolam was used as a comparator in these studies. KRM-II-81 and NS16085 attenuated mechanical allodynia but not thermal hyperalgesia in both pain states, and their effects were attenuated by the benzodiazepine receptor antagonist flumazenil. KRM-II-81 attenuated affective pain-related behavior in the PEAP test. In the operant responding procedure and horizontal wire test, only midazolam produced significant effects at the dose that produced maximal antinociception. In the T-maze assay, only midazolam significantly decreased the percentage of alternation at an antinociceptive dose. Thus, KRM-II-81 and NS16085 but not midazolam selectively produced antinociceptive effects. Collectively, these data suggest that α2/α3 subtype-selective GABAA PAMs could be a novel class of analgesics and warrant further investigation. SIGNIFICANCE STATEMENT: This study demonstrates that α2/α3 subtype-selective GABAA PAMs KRM-II-81 and NS16085 produce selective antinociceptive effects devoid of sedation, myorelaxation, and cognitive impairment in two rat models of persistent pain. This study supports the development of α2/α3 subtype-selective GABAA PAMs, rather than classical benzodiazepines, as safe and novel analgesics for pain management.

Development of Macrocyclic Neurotensin Receptor Type 2 (NTS2) Opioid-Free Analgesics

The opioid crisis has highlighted the urgent need to develop non-opioid alternatives for managing pain, with an effective, safe, and non-addictive pharmacotherapeutic profile. Using an extensive structure-activity relationship approach, here we have identified a new series of highly selective neurotensin receptor type 2 (NTS2) macrocyclic compounds that exert potent, opioid-independent analgesia in various experimental pain models. To our knowledge, the constrained macrocycle in which the Ile12 residue of NT(7-12) was substituted by cyclopentylalanine, Pro7 and Pro10 were replaced by allyl-glycine followed by side-chain to side-chain cyclization is the most selective analog targeting NTS2 identified to date (Ki 2.9 nM), showing 30,000-fold selectivity over NTS1. Of particular importance, this macrocyclic analog is also able to potentiate the analgesic effects of morphine in a dose- and time-dependent manner. Exerting complementary analgesic actions via distinct mechanisms of nociceptive transmission, NTS2-selective macrocycles can therefore be exploited as opioid-free analgesics or as opioid-sparing therapeutics, offering superior pain relief with reduced adverse effects to pain patients.

Compound 4a induces paraptosis in liver cancer through endoplasmic reticulum stress mediated by the calreticulin protein

BACKGROUND AND PURPOSE

Emerging evidence has highlighted that paraptosis may be an effective strategy for treating liver cancer. In our previous studies, Compound 4a induced paraptosis in cancer cells. Here, the characteristics of Compound 4a-induced paraptosis were further revealed and, for the first time, the target and related molecular mechanisms of Compound 4a-induced paraptosis in liver cancer were defined.

EXPERIMENTAL APPROACH

The effects and mechanism of Compound 4a in liver cancer cells were studied in in vitro and in vivo (BALB/c-nude xenograft model) experiments, and the targets of Compound 4a that trigger paraptosis were identified and confirmed via mass spectrometry-based drug affinity responsive target stability (DARTS) analyses, siRNA experiments and a cellular thermal shift assay (CETSA). The function and distribution of calreticulin (CRT) protein were detected via Cal-520 AM and immunofluorescence staining, respectively.

KEY RESULTS

Compound 4a effectively induced paraptosis-like cell death in liver cancer, both in vitro and in vivo, and its effect was comparable with the first-line anti-liver cancer drug oxaliplatin but with a higher safety profile. We identified the CRT protein as a target of Compound 4a, which caused cellular endoplasmic reticulum stress (ERS) and calcium overload. CRT knockdown weakened the anti-liver cancer activity of Compound 4a, which may be related to the inhibition of paraptosis.

CONCLUSION

Compound 4a represents a potentially safe and effective agent for the treatment of liver cancer. The characteristics of Compound 4a-triggered paraptosis was clarified and a unique function of CRT in paraptosis was revealed.

The Oral Health Statistical Guidelines for Reporting Observational Studies and Clinical Trials in Oral Health Research: Manuscript Checklist

Adequate and transparent reporting is necessary for critically appraising published research. Yet, ample evidence suggests that the design, conduct, analysis, interpretation, and reporting of oral health research could be greatly improved. Accordingly, the Task Force on Design and Analysis in Oral Health Research-statisticians and trialists from academia and industry-identified the minimum information needed to report and evaluate observational studies and clinical trials in oral health: the Oral Health Statistical (OHStat) Guidelines. Drafts were circulated to the editors of 85 oral health journals and to Task Force members and sponsors and discussed at a December 2020 workshop attended by 49 researchers. The guidelines were subsequently revised by the Task Force's writing group. The guidelines draw heavily from the Consolidated Standards for Reporting Trials, Strengthening the Reporting of Observational Studies in Epidemiology (STROBE), and Consolidated Standards for Reporting Trials harms guidelines and incorporate the Statistical Analysis and Methods in Published Literature guidelines for reporting statistics, the Clinical and Laboratory Images in Publications principles for documenting images, and the Grading of Recommendations Assessment, Development and Evaluation indicating the quality of evidence. The guidelines also recommend reporting estimates in clinically meaningful units using confidence intervals, rather than relying on P values. In addition, OHStat introduces 7 new guidelines that concern the text itself, such as checking the congruence between abstract and text, structuring the discussion, and listing conclusions to make them more specific. OHStat does not replace other reporting guidelines; it incorporates those most relevant to dental researches into a single document. Manuscripts using the OHStat guidelines will provide more information specific to oral health research.

The OHStat Guidelines for Reporting Observational Studies and Clinical Trials in Oral Health Research: Manuscript Checklist

Adequate and transparent reporting is necessary for critically appraising published research. Yet, ample evidence suggests that the design, conduct, analysis, interpretation, and reporting of oral health research could be greatly improved. Accordingly, the Task Force on Design and Analysis in Oral Health Research-statisticians and trialists from academia and industry-identified the minimum information needed to report and evaluate observational studies and clinical trials in oral health: the OHStat Guidelines. Drafts were circulated to the editors of 85 oral health journals and to Task Force members and sponsors and discussed at a December 2020 workshop attended by 49 researchers. The guidelines were subsequently revised by the Task Force's writing group. The guidelines draw heavily from the Consolidated Standards for Reporting Trials (CONSORT), Strengthening the Reporting of Observational Studies in Epidemiology (STROBE), and CONSORT harms guidelines and incorporate the SAMPL guidelines for reporting statistics, the CLIP principles for documenting images, and the GRADE indicating the quality of evidence. The guidelines also recommend reporting estimates in clinically meaningful units using confidence intervals, rather than relying on P values. In addition, OHStat introduces 7 new guidelines that concern the text itself, such as checking the congruence between abstract and text, structuring the discussion, and listing conclusions to make them more specific. OHStat does not replace other reporting guidelines; it incorporates those most relevant to dental research into a single document. Manuscripts using the OHStat guidelines will provide more information specific to oral health research.

A highly selective inhibitor of discoidin domain receptor-1 (DDR1-IN-1) protects corneal epithelial cells from YAP/ACSL4-mediated ferroptosis in dry eye

BACKGROUND AND PURPOSE

This study investigated the involvement of discoidin domain receptor (DDR) in dry eye and assessed the potential of specific DDR inhibitors as a therapeutic strategy for dry eye by exploring the underlying mechanism.

EXPERIMENTAL APPROACH

Dry eye was induced in Wistar rats by applying 0.2% benzalkonium chloride (BAC), after which rats were treated topically for 7 days with DDR1-IN-1, a selective inhibitor of DDR1. Clinical manifestations of dry eye were assessed on Day-7 post-treatment. Histological evaluation of corneal damage was performed using haematoxylin and eosin (H&E) staining. In vitro, immortalized human corneal epithelial cells (HCECs) exposed to hyperosmotic stress (HS) were treated with varying doses of DDR1-IN-1 for 24 h. The levels of lipid peroxidation in dry eye corneas or HS-stimulated HCECs were assessed. Protein levels of DDR1/DDR2 and related pathways were detected by western blotting. The cellular distribution of acyl-CoA synthetase long chain family member 4 (ACSL4) and Yes-associated protein (YAP) was evaluated using immunohistochemistry or immunofluorescent staining.

KEY RESULTS

In dry eye corneas, only DDR1 expression was significantly up-regulated compared with normal controls. DDR1-IN-1 treatment significantly alleviated dry eye symptoms in vivo. The treatment remarkably reduced lipid hydroperoxide (LPO) levels and suppressed the expression of ferroptosis markers, particularly ACSL4. Overexpression or reactivation of YAP diminished the protective effects of DDR1-IN-1, indicating the involvement of the Hippo/YAP pathway in DDR1-targeted therapeutic effects.

CONCLUSIONS AND IMPLICATIONS

This study confirms the significance of DDR1 in dry eye and highlights the potential of selective DDR1 inhibitor(s) for dry eye treatment.

Sex differences in the effects of N-ethylpentylone in young CD1 mice: Insights on behaviour, thermoregulation and early gene expression

BACKGROUND AND PURPOSE

New psychoactive substances such as N-ethylpentylone (NEP) are continuously emerging in the illicit drug market, and knowledge of their effects and risks, which may vary between sexes, is scarce. Our present study compares some key effects of NEP in male and female mice.

EXPERIMENTAL APPROACH

Psychostimulant, rewarding and reinforcing effects were investigated by tracking locomotor activity, conditioned place preference (CPP) paradigm and through a self-administration (SA) procedure, respectively, in CD1 mice. Moreover, the expression of early genes (C-fos, Arc, Csnk1e, Pdyn, Pp1r1b and Bdnf in addiction-related brain areas) was assessed by qPCR. Finally, serum and brain levels of NEP were determined by UHPLC-MS/MS.

KEY RESULTS

NEP-treated males experimented locomotor sensitisation and showed higher and longer increases in locomotion as well as higher hyperthermia after repeated administration than females. Moreover, while preference score in the CPP was similar in both sexes, extinction occurred later, and reinstatement was more easily established for males. Female mice self-administered more NEP than males at a higher dose. Differences in early gene expression (Arc, Bdnf, Csnk1e and Ppp1r1b) were found, but the serum and brain NEP levels did not differ between sexes.

CONCLUSION AND IMPLICATIONS

Our results suggest that male mice are more sensitive to NEP psychostimulant and rewarding effects. These differences may be attributed to different early gene expression but not to pharmacokinetic factors. Moreover, males appear to be more vulnerable to the hyperthermic effects of NEP, while females might be more prone to NEP abuse.

Extracellular bimolecular fluorescence complementation for investigating membrane protein dimerization: a proof of concept using class B GPCRs

Bimolecular fluorescence complementation (BiFC) methodology uses split fluorescent proteins to detect interactions between proteins in living cells. To date, BiFC has been used to investigate receptor dimerization by splitting the fluorescent protein between the intracellular portions of different receptor components. We reasoned that attaching these split proteins to the extracellular N-terminus instead may improve the flexibility of this methodology and reduce the likelihood of impaired intracellular signal transduction. As a proof-of-concept, we used receptors for calcitonin gene-related peptide, which comprise heterodimers of either the calcitonin or calcitonin receptor-like receptor in complex with an accessory protein (receptor activity-modifying protein 1). We created fusion constructs in which split mVenus fragments were attached to either the C-termini or N-termini of receptor subunits. The resulting constructs were transfected into Cos7 and HEK293S cells, where we measured cAMP production in response to ligand stimulation, cell surface expression of receptor complexes, and BiFC fluorescence. Additionally, we investigated ligand-dependent internalization in HEK293S cells. We found N-terminal fusions were better tolerated with regards to cAMP signaling and receptor internalization. N-terminal fusions also allowed reconstitution of functional fluorescent mVenus proteins; however, fluorescence yields were lower than with C-terminal fusion. Our results suggest that BiFC methodologies can be applied to the receptor N-terminus, thereby increasing the flexibility of this approach, and enabling further insights into receptor dimerization.

Chicoric acid exerts therapeutic effects in DSS-induced ulcerative colitis by targeting the USP9X/IGF2BP2 axis

BACKGROUND AND PURPOSE

Chicoric acid, a hydroxycinnamic acid, exhibits anti-inflammation activities. However, the specific mechanisms underlying the effects of chicoric acid on dextran sulfate sodium (DSS)-induced colitis remain unclear. Here, we aimed to elucidate the molecular mechanisms underlying the protective effects of chicoric acid in DSS-induced colitis.

EXPERIMENTAL APPROACH

Mice with DSS-induced colitis (UC mice) were treated for a week with chicoric acid. Symptoms of colitis, colonic pathology, inflammation-related indicators, and intestinal mucosal barrier function were evaluated. RNA sequencing was performed on colon tissues to obtain differentially expressed genes. The deubiquitinating enzyme USP9X was selected, and the inhibitory and targeting effects of chicoric acid on USP9X were subsequently determined. In vivo and in vitro, DSS-induced colitis was treated with USP9X inhibitors WP1130 and EOAI3402143. Ubiquitination label-free quantitative proteomic analysis was performed to identify protein peptides that may undergo de-ubiquitination by USP9X. Co-immunoprecipitation (Co-IP), immunohistochemistry and western blotting were used to validate in vivo and in vitro results.

KEY RESULTS

Chicoric acid significantly alleviated clinical activity and histological changes, inhibited pro-inflammatory cytokine production and improved integrity of the intestinal barrier in UC mice. Moreover, chicoric acid suppressed USP9X expression in colonic tissues from UC mice. Furthermore, USP9X contributed to promoting the onset of UC and that insulin-like growth factor 2 mRNA-binding protein 2 (IGF2BP2) was deubiquitinated by USP9X.

CONCLUSION AND IMPLICATIONS

Chicoric acid ameliorated DSS-induced colitis by targeting the USP9X/IGF2BP2 axis, indicating that targeting the USP9X/IGF2BP2 axis presents a promising and innovative therapeutic approach for the treatment of UC.