Search

Chronic neuropathic pain is a debilitating pain syndrome caused by damage to the nervous system that is poorly served by current medications. Given these problems, clinical studies have pursued extracts of the plant Cannabis sativa as alternative treatments for this condition. The vast majority of these studies have examined cannabinoids which contain the psychoactive constituent delta-9-tetrahydrocannabinol (THC). While there have been some positive findings, meta-analyses of this clinical work indicates that this effectiveness is limited and hampered by side-effects. This review focuses on how recent preclinical studies have predicted the clinical limitations of THC-containing cannabis extracts, and importantly, point to how they might be improved. This work highlights the importance of targeting channels and receptors other than cannabinoid CB1 receptors which mediate many of the side-effects of cannabis., (© 2023 International Society for Neurochemistry.)

The neuronal glycine transporter GlyT2 removes glycine from the synaptic cleft through active Na + , Cl - , and glycine cotransport contributing to the termination of the glycinergic signal as well as supplying substrate to the presynaptic terminal for the maintenance of the neurotransmitter content in synaptic vesicles. Patients with mutations in the human GlyT2 gene (SLC6A5), develop hyperekplexia or startle disease (OMIM 149400), characterized by hypertonia and exaggerated startle responses to trivial stimuli that may have lethal consequences in the neonates as a result of apnea episodes. Post-translational modifications in cysteine residues of GlyT2 are an aspect of structural interest we analyzed. Our study is compatible with a reversible and short-lived S-acylation in spinal cord membranes, detectable by biochemical and proteomics methods (acyl-Rac binding and IP-ABE) confirmed with positive and negative controls (palmitoylated and non-palmitoylated proteins). According to a short-lived modification, direct labeling using click chemistry was faint but mostly consistent. We have analyzed the physiological properties of a GlyT2 mutant lacking the cysteines with high prediction of palmitoylation and the mutant is less prone to be included in lipid rafts, an effect also observed upon treatment with the palmitoylation inhibitor 2-bromopalmitate. This work demonstrates there are determinants of lipid raft inclusion associated with the GlyT2 mutated cysteines, which are presumably modified by palmitoylation., (© 2024 The Author(s). Journal of Neurochemistry published by John Wiley & Sons Ltd on behalf of International Society for Neurochemistry.)

Mitochondrial enzyme 17β‐hydroxysteroid dehydrogenase type 10 (HSD10) is a potential molecular target for treatment of mitochondrial‐related disorders such as Alzheimer's disease (AD). Its over‐expression in AD brains is one of the critical factors disturbing the homeostasis of neuroprotective steroids and exacerbating amyloid beta (Aβ)‐mediated mitochondrial toxicity and neuronal stress. This study was focused on revalidation of the most potent HSD10 inhibitors derived from benzothiazolyl urea scaffold using fluorescent‐based enzymatic assay with physiologically relevant substrates of 17β‐oestradiol and allopregnanolone. The oestradiol‐based assay led to the identification of two nanomolar inhibitors (IC50 70 and 346 nM) differing from HSD10 hits revealed from the formerly used assay. Both identified inhibitors were found to be effective also in allopregnanolone‐based assay with non‐competitive or uncompetitive mode of action. In addition, both inhibitors were confirmed to penetrate the HEK293 cells and they were able to inhibit the HSD10 enzyme in the cellular environment. Both molecules seem to be potential lead structures for further research and development of HDS10 inhibitors. [ABSTRACT FROM AUTHOR]

C9orf72‐derived dipeptide repeats (DPRs) proteins have been regarded as the pathogenic cause of neurodegeneration in amyotrophic lateral sclerosis and frontotemporal dementia (C9‐ALS/FTD). As the most toxic DPRs in C9‐ALS/FTD, poly‐proline‐arginine (poly‐PR) is associated with the stability and accumulation of p53, which consequently induces neurodegeneration. However, the exact molecular mechanism via which C9orf72 poly‐PR stabilizes p53 remains unclear. In this study, we showed that C9orf72 poly‐PR induces not only neuronal damage but also p53 accumulation and p53 downstream gene activation in primary neurons. C9orf72 (PR)50 also slows down p53 protein turnover without affecting the p53 transcription level and thus promotes its stability in N2a cells. Interestingly, the ubiquitin‐proteasome system but not the autophagy function was impaired in (PR)50 transfected N2a cells, resulting in defective p53 degradation. Moreover, we found that (PR)50 induces mdm2 mistranslocation from the nucleus to the cytoplasm and competitively binds to p53, reducing mdm2‐p53 interactions in the nucleus in two different (PR)50 transfected cells. Our data strongly indicate that (PR)50 reduces mdm2‐p53 interactions and causes p53 to escape from the ubiquitin‐proteasome system, promoting its stability and accumulation. Inhibiting or at least downregulating (PR)50 binding with p53 may be therapeutically exploited for the treatment of C9‐ALS/FTD. [ABSTRACT FROM AUTHOR]

In countries around the world, sleep deprivation represents a widespread problem affecting school‐age children, teenagers, and adults. Acute sleep deprivation and more chronic sleep restriction adversely affect individual health, impairing memory and cognitive performance as well as increasing the risk and progression of numerous diseases. In mammals, the hippocampus and hippocampus‐dependent memory are vulnerable to the effects of acute sleep deprivation. Sleep deprivation induces changes in molecular signaling, gene expression and may cause changes in dendritic structure in neurons. Genome wide studies have shown that acute sleep deprivation alters gene transcription, although the pool of genes affected varies between brain regions. More recently, advances in research have drawn attention to differences in gene regulation between the level of the transcriptome compared with the pool of mRNA associated with ribosomes for protein translation following sleep deprivation. Thus, in addition to transcriptional changes, sleep deprivation also affects downstream processes to alter protein translation. In this review, we focus on the multiple levels through which acute sleep deprivation impacts gene regulation, highlighting potential post‐transcriptional and translational processes that may be affected by sleep deprivation. Understanding the multiple levels of gene regulation impacted by sleep deprivation is essential for future development of therapeutics that may mitigate the effects of sleep loss. [ABSTRACT FROM AUTHOR]

Alzheimer's disease (AD) is a progressive neurodegenerative disease originating partly from amyloid β protein‐induced synaptic failure. As damaging of noradrenergic neurons in the locus coeruleus (LC) occurs at the prodromal stage of AD, activation of adrenergic receptors could serve as the first line of defense against the onset of the disease. Activation of β2‐ARs strengthens long‐term potentiation (LTP) and synaptic activity, thus improving learning and memory. Physical stimulation of animals exposed to an enriched environment (EE) leads to the activation of β2‐ARs and prevents synaptic dysfunction. EE also suppresses neuroinflammation, suggesting that β2‐AR agonists may play a neuroprotective role. The β2‐AR agonists used for respiratory diseases have been shown to have an anti‐inflammatory effect. Epidemiological studies further support the beneficial effects of β2‐AR agonists on several neurodegenerative diseases. Thus, I propose that β2‐AR agonists may provide therapeutic value in combination with novel treatments for AD. [ABSTRACT FROM AUTHOR]

17β‐hydroxysteroid dehydrogenase (17β‐HSD10) is a multifunctional human enzyme with important roles both as a structural component and also as a catalyst of many metabolic pathways. This mitochondrial enzyme has important functions in the metabolism, development and aging of the neural system, where it is involved in the homeostasis of neurosteroids, especially in regard to estradiol, changes in which make it an essential part of neurodegenerative pathology. These roles therefore, indicate that 17β‐HSD10 may be a possible druggable target for neurodegenerative diseases including Alzheimer's disease (AD), and in hormone‐dependent cancer. The objective of this review was to provide a summary about physiological functions and pathological roles of 17β‐HSD10 and the modulators of its activity. [ABSTRACT FROM AUTHOR]

Lanthanum exerts adverse effects on the central nervous system. However, the mechanism underlying these adverse effects has not been clarified. It is known that oxidative stress plays an important role in neurological injuries induced by harmful factors. Nuclear factor erythroid 2-related factor (Nrf2) is very important in the response to oxidative stress in tissues and cells. The purpose of this study was to explore the effect of lanthanum chloride (LaCl3) on the spatial learning and memory of rats and to determine whether the Nrf2/antioxidant response element pathway acts in the hippocampus. Four groups of Wistar rats were exposed to 0 mM, 9 mM, 18 mM or 36 mM LaCl3 through their drinking water from the day of birth to 2 months after weaning. The results showed that LaCl3 impaired the spatial learning and memory of the rats, damaged the neuronal ultrastructure, increased reactive oxygen species levels and significantly down-regulated Nrf2 as well as the mRNA and protein expression of Nrf2-regulated genes, including NADP(H): dehydrogenase quinone 1, haeme oxygenase-1, superoxide dismutase 2, glutathione peroxidase 1, glutathione- S-transferase, γ-glutamine cysteine synthase and glutathione reductase, in the hippocampus. This study suggests that LaCl3 can impair the spatial learning and memory of rats, possibly by perturbing the Nrf2/antioxidant response element signalling pathway. [ABSTRACT FROM AUTHOR]

Allosteric modulation of G-protein coupled receptors ( GPCRs) represents a novel approach for fine-tuning GPCR functions. The cannabinoid CB1 receptor, a GPCR associated with the CNS, has been implicated in the treatment of drug addiction, pain, and appetite disorders. We report here the synthesis and pharmacological characterization of two indole-2-carboxamides:5-chloro-3-ethyl-1-methyl-N-(4-(piperidin-1-yl)phenethyl)-1 H-indole-2-carboxamide ( ICAM-a) and 5-chloro-3-pentyl-N-(4-(piperidin-1-yl)phenethyl)-1 H-indole-2-carboxamide ( ICAM-b). Although both ICAM-a and ICAM-b enhanced CP55, 940 binding, ICAM-b exhibited the strongest positive cooperativity thus far demonstrated for enhancing agonist binding to the CB1 receptor. Although it displayed negative modulatory effects on G-protein coupling to CB1, ICAM-b induced β-arrestin-mediated downstream activation of extracellular signal-regulated kinase ( ERK) signaling. These results indicate that this compound represents a novel class of CB1 ligands that produce biased signaling via CB1. [ABSTRACT FROM AUTHOR]

Traumatic brain injury ( TBI) results in significant inflammation which contributes to the evolving pathology. Previously, we have demonstrated that cyclic AMP ( cAMP), a molecule involved in inflammation, is down-regulated after TBI. To determine the mechanism by which cAMP is down-regulated after TBI, we determined whether TBI induces changes in phosphodiesterase ( PDE) expression. Adult male Sprague Dawley rats received moderate parasagittal fluid-percussion brain injury ( FPI) or sham injury, and the ipsilateral, parietal cortex was analyzed by western blotting. In the ipsilateral parietal cortex, expression of PDE1A, PDE4B2, and PDE4D2, significantly increased from 30 min to 24 h post-injury. PDE10A significantly increased at 6 and 24 h after TBI. Phosphorylation of PDE4A significantly increased from 6 h to 7 days post-injury. In contrast, PDE1B, PD4A5, and PDE4A8 significantly decreased after TBI. No changes were observed with PDE1C, PDE3A, PDE4B1/3, PDE4B4, PDE4D3, PDE4D4, PDE8A, or PDE8B. Co-localization studies showed that PDE1A, PDE4B2, and phospho- PDE4A were neuronally expressed, whereas PDE4D2 was expressed in neither neurons nor glia. These findings suggest that therapies to reduce inflammation after TBI could be facilitated with targeted therapies, in particular for PDE1A, PDE4B2, PDE4D2, or PDE10A. [ABSTRACT FROM AUTHOR]

J. Neurochem. (2010) 112, 1442–1453. There is much evidence to suggest that G protein coupled receptors exist as oligomers but the relevance to their function is unclear. We have, therefore, examined the binding of the radiolabelled agonist [3H]NPA to membranes of CHO cells expressing the D2 dopamine receptor in dissociation rate experiments. When [3H]NPA dissociation was started by dilution, the dissociation rate in the absence of sodium ions was unaffected by addition of the antagonist/inverse agonist (+)-butaclamol, but was accelerated by addition of agonists e.g. dopamine, suggesting that the receptor was not behaving as a monomer with a single binding site. The very low efficacy partial agonist, aripiprazole provided an intermediate level of acceleration of dissociation. [3H]NPA dissociation experiments started by addition of ligands without dilution gave a similar pattern. [3H]NPA dissociation could also be accelerated by GTP. Dissociation of [3H]NPA in the presence of GTP and dopamine provided a greater acceleration than for either modulator alone, suggesting synergistic effects related to receptor/G protein interaction. When [3H]NPA dissociation experiments were performed in the presence of sodium ions, dissociation was faster than in their absence but the rate still depended on the ligand present in the assay. Overall the data cannot be explained by a ternary complex model and are consistent with an oligomeric receptor in which binding of [3H]NPA, as an example of an agonist ligand, can be modulated co-operatively by ligands binding elsewhere in the oligomer. Interactions with G proteins also occurs providing further modulation of [3H]NPA binding. Both agonists and G proteins are proposed to modulate the oligomer by switching high affinity agonist binding sites to low affinity sites. [ABSTRACT FROM AUTHOR]

Previous studies indicate that the endocannabinoid system is a potential target for the treatment of depression. To further examine this question we assessed the effects of electroconvulsive shock (ECS) treatment, both a single session and 10 daily sessions, on endocannabinoid content, CB1 receptor binding parameters and CB1 receptor-mediated [35S]GTPγS binding in the prefrontal cortex, hippocampus, hypothalamus and amygdala. A single ECS session resulted in a general reduction in the binding affinity of the CB1 receptor in all brain regions examined, as well as reductions in N-arachidonylethanolamine (anandamide) content in the prefrontal cortex and the hippocampus, reduced hydrolysis of anandamide by fatty acid amide hydrolase (FAAH) in the prefrontal cortex and an increase in the binding site density of the CB1 receptor in the amygdala. Following 10 ECS sessions, all these effects subsided except for the reductions in anandamide content in the prefrontal cortex, which increased in magnitude, as well as the reductions in FAAH activity in the prefrontal cortex. Additionally, repeated ECS treatment resulted in a significant reduction in the binding site density of the CB1 receptor in the prefrontal cortex, but did not alter CB1 receptor-mediated [35S]GTPγS binding. Repeated ECS treatment also significantly enhanced the sensitivity of CB1 receptor-mediated [35S]GTPγS binding in the amygdala. Collectively, these data demonstrate that ECS treatment results in a down-regulation of cortical and an up-regulation of subcortical endocannabinoid activity, illustrating the possibility that the role of the endocannabinoid system in affective illness may be both complex and regionally specific. [ABSTRACT FROM AUTHOR]

Serotonin 5-HT2C receptors (5-HT2CRs) are almost exclusively expressed in the CNS, and implicated in disorders such as obesity, depression, and schizophrenia. The present study investigated the mechanisms governing the coupling of the 5-HT2CR to the extracellular signal-regulated kinases (ERKs) 1/2, using a Chinese hamster ovary (CHO) cell line stably expressing the receptor at levels comparable to those found in the brain. Using the non-RNA-edited isoform of the 5-HT2CR, constitutive ERK1/2 phosphorylation was observed and found to be modulated by full, partial and inverse agonists. Interestingly, agonist-directed trafficking of receptor stimulus was also observed when comparing effects on phosphoinositide accumulation and intracellular Ca2+ elevation to ERK1/2 phosphorylation, whereby the agonists,[±]-2,5-dimethoxy-4-iodoamphetamine (DOI) and quipazine, showed reversal of efficacy between the phosphoinositide/Ca2+ pathways, on the one hand, and the ERK1/2 pathway on the other. Subsequent molecular characterization found that 5-HT-stimulated ERK1/2 phosphorylation in this cellular background requires phospholipase D, protein kinase C, and activation of the Raf/MEK/ERK module, but is independent of both receptor- and non-receptor tyrosine kinases, phospholipase C, phosphoinositide 3-kinase, and endocytosis. Our findings underscore the potential for exploiting pathway-selective receptor states in the differential modulation of signaling pathways that play prominent roles in normal and abnormal neuronal signaling. [ABSTRACT FROM AUTHOR]

The hydrolysis of cyclic nucleotide second messengers takes place through multiple cyclic nucleotide phosphodiesterases (PDEs). The significance of this diversification is not fully understood. Here we report the differential regulation of low K[sub m] Ca[sup 2+]-activated (PDE1C) and Ca[sup 2+]-independent, rolipram-sensitive (PDE4) PDEs by protein phosphorylation in the neuroendocrine cell line AtT20. Incubation of cells with 8-(4-chlorophenylthio)-cyclic AMP (CPT-cAMP) enhanced PDE4 and reduced PDE1C activity. These effects were blocked by H89 indicating mediation by cAMP-dependent protein kinase (PKA), furthermore in broken cell preparations PKA produced the same reciprocal changes of PDE activities. Calyculin A, an inhibitor of protein phosphatases 1 and 2 A, stimulated PDE4 and enhanced the inhibitory effect of CPT-cAMP on PDE1C. The reduction of PDE1C activity was characterized by a marked attenuation of the activation by Ca[sup 2+]/calmodulin. Stimulation of PDE4 activity by CPT-cAMP or calyculin A was attributable to PDE4D3 and these effects could also be reproduced in human embryonic kidney cells expressing epitope-tagged PDE4D3. Together, these data show reciprocal regulation of PDE1C and PDE4D by PKA, which represents a novel scheme for plasticity in intracellular signalling. [ABSTRACT FROM AUTHOR]