Pharmacological Reports最新文献

The group III metabotropic glutamate receptors (mGluRs), comprising mGluR4, mGluR6, mGluR7, and mGluR8, offer neuroprotective potential in mitigating excitotoxicity during ischemic brain injury, particularly in neonatal contexts. They are G-protein coupled receptors that inhibit adenylyl cyclase and reduce neurotransmitter release, mainly located presynaptically and acting as autoreceptors. This review aims to examine the differential expression and function of group III mGluRs across various brain regions such as the cortex, hippocampus, and cerebellum, with a special focus on the neonatal stage of development. Glutamate excitotoxicity plays a crucial role in the pathophysiology of brain ischemia in neonates. While ionotropic glutamate receptors are traditional targets for neuroprotection, their direct inhibition often leads to severe side effects due to their critical roles in normal neurotransmission and synaptic plasticity. Group III mGluRs provide a more nuanced and potentially safer approach by modulating rather than blocking glutamatergic transmission. Their downstream signaling cascade results in the regulation of intracellular calcium levels, neuronal hyperpolarization, and reduced neurotransmitter release, effectively decreasing excitotoxic signaling without completely suppressing essential glutamatergic functions. Importantly, the neuroprotective effects of group III mGluRs extend beyond direct modulation of glutamate release influencing glial cell function, neuroinflammation, and oxidative stress, all of which contribute to secondary injury cascades in brain ischemia. This comprehensive analysis of group III mGluRs multifaceted neuroprotective potential provides valuable insights for developing novel therapeutic strategies to combat excitotoxicity in neonatal ischemic brain injury.

Injury to the developing central nervous system resulting from perinatal hypoxia–ischemia (HI) is still a clinical challenge. The only approach currently available in clinical practice for severe cases of HI is therapeutic hypothermia, initiated shortly after birth and supported by medications to regulate blood pressure, control epileptic seizures, and dialysis to support kidney function. However, these treatments are not effective enough to significantly improve infant survival or prevent brain damage. The need to create a new effective therapy has focused attention on metabotropic glutamate receptors (mGluR), which control signaling pathways involved in HI-induced neurodegeneration. The complexity of mGluR actions, considering their localization and developmental changes, and the functions of each subtype in HI-evoked brain damage, combined with difficulties in the availability of safe and effective modulators, raises the question whether modulation of mGluRs with subtype-selective ligands can become a new treatment in neonatal HI. Addressing this question, this review presents the available information concerning the role of each of the eight receptor subtypes of the three mGluR groups (group I, II, and III). Data obtained from experiments performed on in vitro and in vivo neonatal HI models show the neuroprotective potential of group I mGluR antagonists, as well as group II and III agonists. The information collected in this work indicates that the neuroprotective effects of manipulating mGluR in experimental HI models, despite the need to create more safe and selective ligands for particular receptors, provide a chance to create new therapies for the sensitive brains of infants at risk.

Background

The mechanistic target of rapamycin (mTOR) is a crucial regulator of cell metabolic activity. It forms part of several distinct protein complexes, particularly mTORC1 and mTORC2. The lack of specific inhibitors still hampers the attribution of mTOR functions to these complexes. JR-AB2-011 has been reported as a specific mTORC2 inhibitor preventing mTOR binding to RICTOR, a unique component of mTORC2. We aimed to describe the effects of JR-AB2-011 in leukemia/lymphoma cells, where the mTOR pathway is often aberrantly activated.

Methods

The impact of JR-AB2-011 on leukemia/lymphoma cell metabolism was analyzed using the Seahorse platform. AKT phosphorylation at Ser473 was used as a marker of mTORC2 activity. mTOR binding to RICTOR was assessed by co-immunoprecipitation. RICTOR-null cells were derived from the Karpas-299 cell line using CRISPR/Cas9 gene editing.

Results

In leukemia/lymphoma cell lines, JR-AB2-011 induced a rapid drop in the cell respiration rate, which was variably compensated by an increased glycolytic rate. In contrast, an increase in the respiration rate due to JR-AB2-011 treatment was observed in primary leukemia cells. Unexpectedly, JR-AB2-011 did not affect AKT Ser473 phosphorylation. In addition, mTOR did not dissociate from RICTOR in cells treated with JR-AB2-011 under the experimental conditions used in this study. The effect of JR-AB2-011 on cell respiration was retained in RICTOR-null cells.

Conclusion

JR-AB2-011 affects leukemia/lymphoma cell metabolism via a mechanism independent of mTORC2.

Background

Loop diuretics became a cornerstone in the therapy of hypervolemia in patients with chronic kidney disease or heart failure. Apart from the influence on water and electrolyte balance, these drugs were shown to inhibit tissue fibrosis and renin-angiotensin-system activity. The kynurenine (KYN) pathway products are suggested to be uremic toxins. Kynurenic acid (KYNA) is synthesized by kynurenine aminotransferases (KATs) in the brain and periphery. The cardiovascular and renal effects of KYNA are well documented. However, high KYNA levels have been correlated with the rate of kidney damage and its complications. Our study aimed to assess the effect of loop diuretics, ethacrynic acid, furosemide, and torasemide on KYNA synthesis and KATs activity in rat kidneys in vitro.

Methods

Quantitative analyses of KYNA were performed using fluorimetric HPLC detection. Additionally, molecular docking studies determined the possible interactions of investigated compounds with an active site of KAT I and KAT II.

Results

All studied drugs inhibited KYNA production in rat kidneys in vitro at 0.5–1.0 mmol/l concentrations. Only ethacrynic acid at 1.0 mmol/l concentration significantly lowered KAT I and KAT II activity in kidney homogenates, whereas other drugs were ineffective. Molecular docking results indicated the common binding site for each of the studied loop diuretics and KYNA. They suggested possible residues involved in their binding to the active site of both KAT I and KAT II model.

Conclusions

Our study reveals that loop diuretics may decrease KYNA synthesis in rat kidneys in vitro. The presented results warrant further research in the context of KYN pathway activity regulation by loop diuretics.

Graphical abstract

Glutamate is the major excitatory neurotransmitter in the central nervous system (CNS). Gliomas, malignant brain tumors with a dismal prognosis, alter glutamate homeostasis in the brain, which is advantageous for their growth, survival, and invasion. Alterations in glutamate homeostasis result from its excessive production and release to the extracellular space. High glutamate concentration in the tumor microenvironment destroys healthy tissue surrounding the tumor, thus providing space for glioma cells to expand. Moreover, it confers neuron hyperexcitability, leading to epilepsy, a common symptom in glioma patients. This mini-review briefly describes the biochemistry of glutamate production and transport in gliomas as well as the activation of glutamate receptors. It also summarizes the current pre-clinical and clinical studies identifying pharmacotherapeutics targeting glutamate transporters and receptors emerging as potential therapeutic strategies for glioma.

Background

Intra-detrusor injection of botulinum neurotoxin type A (BoNT/A) is recommended as a possible treatment for patients with overactive bladder (OAB) in whom first-line therapies have failed. The c.190T > C (rs4994) polymorphism in the gene encoding the beta-3 adrenergic receptor (ADRB3) has been suggested to be associated with predisposition to OAB or with response to OAB treatment via a cholinergic muscarinic receptor antagonist. This prospective study aimed to use a urodynamic parameter-based assessment of response, six months after a single intra-detrusor injection of BoNT/A in female OAB patients, to elucidate possible association with the ADRB3 polymorphism.

Methods

The study group consisted of 138 consecutive, Polish, adult, female OAB patients. Urodynamic parameters were recorded before injection of BoNT/A and at six months after administration. ADRB3:rs4994 variants were identified by the sequencing of genomic DNA extracted from buccal swabs.

Results

Apart from baseline, and relative, increase in Maximum Cystometric Capacity (MCC) six months after BoNT/A injection, no significant differences were found in urodynamic parameters between reference TT homozygotes and women with at least one C allele.

Conclusions

Our results do not exclude that ADRB3:rs4994 variants are associated with a positive urodynamic test-based response to intra-detrusor injection of BoNT/A in females with OAB.

In recent years, fluorescent sensors are enjoying a surge of popularity in the field of neuroscience. Through the development of novel genetically encoded sensors as well as improved methods of detection and analysis, fluorescent sensing has risen as a new major technique in neuroscience alongside molecular, electrophysiological, and imaging methods, opening up new avenues for research. Combined with multiphoton microscopy and fiber photometry, these sensors offer unique advantages in terms of cellular specificity, access to multiple targets - from calcium dynamics to neurotransmitter release to intracellular processes - as well as high capability for in vivo interrogation of neurobiological mechanisms underpinning behavior. Here, we provide a brief overview of the method, present examples of its integration with other tools in recent studies ranging from cellular to systems neuroscience, and discuss some of its principles and limitations, with the aim of introducing new potential users to this rapidly developing and potent technique.

Background: Spontaneous preterm birth is the leading cause of perinatal morbidity and mortality. Tocolytics are drugs used to inhibit uterine contractions in cases of imminent preterm birth, however, few are effective in stopping labour once initiated and all have side effects. Combination approaches involving drugs that target multiple signalling pathways that regulate contractions may increase efficacy, reduce dosage and improve tolerability. Both non-steroidal anti-inflammatory drugs (NSAIDs) and hydrogen sulphide (H₂S)-releasing compounds can reduce myometrial contractions. In a novel approach we evaluated the tocolytic properties of ATB-346-a H₂S-releasing derivative of the NSAID naproxen, shown clinically to reduce pain and inflammation in arthritis.

Methods: Using organ baths, paired strips of human myometrium were exposed to increasing concentrations of ATB-346, or equimolar concentrations (10µM and 30µM) of the parent drug, naproxen, or the H₂S-releasing moiety, 4-hydroxy-thiobenzamide (TBZ), alone. The ability of ATB-346 versus the individual components of ATB-346 to decrease ex vivo spontaneous contractions was investigated, and the potency was compared to a known H₂S donor, Na₂S.

Results: Acute application of Na₂S produced a concentration-dependent decrease in force amplitude and force integral (area under the curve) of contraction. ATB-346 produced a more profound decrease in contraction compared to equimolar concentrations of naproxen or TZB alone and was more potent than the equivalent concentration of Na₂S.

Conclusions: ATB-346 exhibits potent tocolytic properties in human myometrium. These exciting results call for further exploration of ATB-346, with a view to repurposing this or similar drugs as novel therapies for delaying preterm labour.

Background: This study examines self-reported sleep alterations in treatment-resistant depression (TRD) inpatients following intravenous ketamine administration.

Methods: This is a post-hoc analysis of a naturalistic observational study, which enrolled 28 inpatients with treatment-resistant major depressive disorder and analyzed self-reported sleep changes (items 1-4; 'insomnia', 'nighttime restlessness', 'early morning waking', 'hypersomnia') in Inventory of Depressive Symptomatology 30-item (IDS SR-30) in responders and non-responders stratified per Montgomery-Åsberg Depression Rating Scale (MADRS) during short-term ketamine treatment.

Results: Responders, as well as non-responders, did not experience significant changes in IDS SR-30 sleep items ('insomnia', 'nighttime restlessness', 'early morning waking', 'hypersomnia') (p's > 0.05) at 7-day follow-up after eight intravenous ketamine infusions as compared to baseline.

Conclusion: Neither responders, nor non-responders reported any significant alterations in sleep patterns during ketamine infusions. These findings are not in line with current literature, as so far modest improvements in sleep during ketamine treatment have been reported. Results should be interpreted with caution, primarily due to the small sample size.