Impaired Neurotransmission Research Articles

New Insights into the Development of Donepezil-Based Hybrid and Natural Molecules as Multi-Target Drug Agents for Alzheimer’s Disease Treatment

Alzheimer’s disease (AD) involves a complex pathophysiology with multiple interconnected subpathologies, including protein aggregation, impaired neurotransmission, oxidative stress, and microglia-mediated neuroinflammation. Current treatments, which generally target a single subpathology, have failed to modify the disease’s progression, providing only temporary symptom relief. Multi-target drugs (MTDs) address several subpathologies, including impaired aggregation of pathological proteins. In this review, we cover hybrid molecules published between 2014 and 2024. We offer an overview of the strategies employed in drug design and approaches that have led to notable improvements and reduced hepatotoxicity. Our aim is to offer insights into the potential development of new Alzheimer’s disease drugs. This overview highlights the potential of multi-target drugs featuring heterocycles with N-benzylpiperidine fragments and natural compounds in improving Alzheimer’s disease treatment.

Effects of diuron and two of its metabolites in biochemical markers and behavior of zebrafish larvae.

Diuron (3-(3,4-dichlorophenyl)-1,1-dimethylurea) is an herbicide used in many crops, including sugar cane cultivation. It is commonly found in aquatic ecosystem and is of high concern due to its ability to persist in the environment. Diuron metabolites include DCA (3,4-dichloroaniline) and DCPMU (3-(3,4-dichlorophenyl-1-methylurea). The objective of this study was to evaluate the effects of diuron and two of its metabolites in zebrafish (Danio rerio) developing embryos, from biochemical to individual level. Activities of the enzymes acetylcholinesterase (AChE), catalase (CAT), glutathione-S-transferase (GST), andlactate dehydrogenase (LDH) and the levels of lipid peroxidation (LPO), swimming activity, and body length were investigated after an exposure of 120h, and the heart rate was determined after 48h of exposure. The range of concentrations tested was 0.003-3.000mg/L diuron, 0.020-1.500mg/L DCA, and 0.020-2.100mg/L DCPMU. Results showed that AChE activity was inhibited by diuron (3.000mg/L) and DCPMU (0.326, 0.828mg/L). However, the swimming activity of fish larvae exposed to diuron or its metabolites was not affected. The CAT was induced by DCPMU, and GST was induced by diuron. This suggests that CAT is acting to cope with oxidative stress induced by DCPMU and GST might have a role in the detoxification of diuron. In addition, larvae exposed to DCA (0.633 and 1.500mg/L) had a reduction in their length, and larvae exposed to diuron (0.754 and 3.000mg/L) and DCA (0.267, 0.633, and 1.500mg/L) presented bradycardia, suggesting cardiotoxicity. Overall, results indicate that diuron, DCA, or DCPMU induces adverse effects during the early phases of zebrafish development, such as the impairment of neurotransmission and cardiovascular function and alterations in antioxidant enzymes and growth. Diuron appeared as more toxic than its metabolites since the lowest LOEC (0.012mg/L) and higher integrated biomarker response (IBR) values were obtained with exposure to this herbicide. Furthermore, as it is fast degraded into DCA and DCPMU, which also affected the zebrafish developing embryos at environmentally relevant concentrations, its use might be of concern in ecosystems that receive agriculture runoff due to their potential adverse effects to aquatic biota.

Beneficial effects of CHF6467, a modified human nerve growth factor, in experimental neonatal hypoxic-ischaemic encephalopathy.

Therapeutic hypothermia (TH) has become the standard care to reduce morbidity and mortality in neonates affected by moderate-to-severe hypoxic-ischaemic encephalopathy (HIE). Despite the use of TH for HIE, the incidence of mortality and disabilities remains high. Nerve growth factor (NGF) is a potent neurotrophin, but clinical use is limited by its pain eliciting effects. CHF6467 is a recombinant modified form of human NGF devoid of algogenic activity (painless NGF). In rodent hippocampal slices exposed to oxygen and glucose deprivation, CHF6467 protected neurons from death and reverted neurotransmission impairment when combined with hypothermia. In a model of rat neonatal HIE, intranasal CHF6467 (20 μg kg-1) significantly reduced brain infarct volume versus vehicle when delivered 10min or 3h after the insult. CHF6467 (20 and 40 μg kg-1, i.n.), significantly decreased brain infarct volume to a similar extent to TH and when combined, showed a synergistic neuroprotective effect. CHF6467 (20 μg kg-1, i.n.) per se and in combination with hypothermia reversed locomotor coordination impairment (Rotarod test) and memory deficits (Y-maze and novel object recognition test) in the neonatal HIE rat model. Intranasal administration of CHF6467 resulted in meaningful concentrations in the brain, blunted HIE-induced mRNA elevation of brain neuroinflammatory markers and, when combined to TH, significantly counteracted the increase in plasma levels of neurofilament light chain, a peripheral marker of neuroaxonal damage. CHF6467 administered intranasally is a promising therapy, in combination with TH, for the treatment of HIE.

A Complex Relationship Among the Circadian Rhythm, Reward Circuit and Substance Use Disorder (SUD).

The human brain not only controls the various physiological functions but is also the prime regulator of circadian rhythms, rewards, and behaviors. Environmental factors, professional stress, and social disintegration are regarded as the initial causative factors of addiction behavior. Shift work, artificial light exposure at night, and chronic and acute jet lag influence circadian rhythm dysfunction. The result is impaired neurotransmitter release, dysfunction of neural circuits, endocrine disturbance, and metabolic disorder, leading to advancement in substance use disorder. There is a bidirectional relationship between chronodisruption and addiction behavior. Circadian rhythm dysfunction, neuroadaptation in the reward circuits, and alteration in clock gene expression in the mesolimbic areas influence substance use disorder (SUD), and chronotherapy has potential benefits in the treatment strategies. This review explores the relationship among the circadian rhythm dysfunction, reward circuit, and SUD. The impact of chronotherapy on SUD has also been discussed.

Inhibitory gamma-aminobutyric acidergic neurons in the anterior cingulate cortex participate in the comorbidity of pain and emotion.

Pain is often comorbid with emotional disorders such as anxiety and depression. Hyperexcitability of the anterior cingulate cortex has been implicated in pain and pain-related negative emotions that arise from impairments in inhibitory gamma-aminobutyric acid neurotransmission. This review primarily aims to outline the main circuitry (including the input and output connectivity) of the anterior cingulate cortex and classification and functions of different gamma-aminobutyric acidergic neurons; it also describes the neurotransmitters/neuromodulators affecting these neurons, their intercommunication with other neurons, and their importance in mental comorbidities associated with chronic pain disorders. Improving understanding on their role in pain-related mental comorbidities may facilitate the development of more effective treatments for these conditions. However, the mechanisms that regulate gamma-aminobutyric acidergic systems remain elusive. It is also unclear as to whether the mechanisms are presynaptic or postsynaptic. Further exploration of the complexities of this system may reveal new pathways for research and drug development.

Holistic assessment of dimethoate toxicity in Carcinus aestuarii's muscle tissues.

Dimethoate (DMT) is one of the most harmful and commonly used organophosphate pesticides in agricultural lands to control different groups of parasitic insects. However, this pesticide is considered a dangerous pollutant for aquatic organisms following its infiltration in coastal ecosystems through leaching. Yet, our investigation aimed to gain new insights into the toxicity mechanism of DMT in the muscles of the green crab Carcinus aestuarii, regarding oxidative stress, neurotransmission impairment, histological aspects, and changes in lipid composition, assessed for the first time on the green crab's muscle. Specimens of C. aestuarii were exposed to 50, 100, and 200µg DMTL-1 for 24h. Compared to the negative control group, the higher the DMT concentration, the lower the saturated fatty acids (SFA), and the higher the monounsaturated fatty acids (MUFA). The significant increase in polyunsaturated fatty acid n-6 (PUFA n-6) was related to the high release, mainly, of linoleic acid (LA, C18: 2n6) and arachidonic acid (ARA, C20: 4n6) levels. Biochemical biomarkers showed that DMT exposure promoted oxidative stress, highlighted by increased levels of hydrogen peroxide (H2O2), malondialdehyde (MDA), advanced oxidation protein product levels (AOPP), and protein carbonyl (PCO). Furthermore, the antioxidant defense system was activated, as demonstrated by the significant changes in the enzymatic activity of superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), and reduced glutathione (GSH) levels associated with an adaptation process of C. aestuarii to cope with the DMT exposure. This pesticide significantly impairs the neurotransmission process, as evidenced by the inhibition of acetylcholinesterase (AChE) activity. Finally, several histopathological changes were revealed in DMT-treated crabs, including vacuolation, and muscle bundle loss.This research offered new insights into the toxic mechanism of DMT, pointing to the usefulness of fatty acid (FA) composition as a sensitive biomarker in littoral crabs.

Chronic pharmacologic manipulation of dopamine transmission ameliorates metabolic disturbance in Trappc9-linked brain developmental syndrome.

Loss-of-function mutations of the gene encoding the trafficking protein particle complex subunit 9 (Trappc9) cause autosomal recessive intellectual disability and obesity by unknown mechanisms. Genome-wide analysis links Trappc9 to nonalcoholic fatty liver disease (NAFLD). Trappc9-deficient mice have been shown to appear overweight shortly after weaning. Here, we analyzed serum biochemistry and histology of adipose and liver tissues to determine the incidence of obesity and NAFLD in Trappc9-deficient mice and combined transcriptomic and proteomic analyses, pharmacological studies, and biochemical and histological examinations of postmortem mouse brains to unveil mechanisms involved. We found that Trappc9-deficient mice presented with systemic glucose homeostatic disturbance, obesity, and NAFLD, which were relieved upon chronic treatment combining dopamine receptor D2 (DRD2) agonist quinpirole and DRD1 antagonist SCH23390. Blood glucose homeostasis in Trappc9-deficient mice was restored upon administering quinpirole alone. RNA-sequencing analysis of DRD2-containing neurons and proteomic study of brain synaptosomes revealed signs of impaired neurotransmitter secretion in Trappc9-deficient mice. Biochemical and histological studies of mouse brains showed that Trappc9-deficient mice synthesized dopamine normally, but their dopamine-secreting neurons had a lower abundance of structures for releasing dopamine in the striatum. Our study suggests that Trappc9 loss of function causes obesity and NAFLD by constraining dopamine synapse formation.

Synapse-Specific Trapping of SNARE Machinery Proteins in the Anesthetized Drosophila Brain.

General anesthetics disrupt brain network dynamics through multiple pathways, in part through postsynaptic potentiation of inhibitory ion channels as well as presynaptic inhibition of neuroexocytosis. Common clinical general anesthetic drugs, such as propofol and isoflurane, have been shown to interact and interfere with core components of the exocytic release machinery to cause impaired neurotransmitter release. Recent studies however suggest that these drugs do not affect all synapse subtypes equally. We investigated the role of the presynaptic release machinery in multiple neurotransmitter systems under isoflurane general anesthesia in the adult female Drosophila brain using live-cell super-resolution microscopy and optogenetic readouts of exocytosis and neural excitability. We activated neurotransmitter-specific mushroom body output neurons and imaged presynaptic function under isoflurane anesthesia. We found that isoflurane impaired synaptic release and presynaptic protein dynamics in excitatory cholinergic synapses. In contrast, isoflurane had little to no effect on inhibitory GABAergic or glutamatergic synapses. These results present a distinct inhibitory mechanism for general anesthesia, whereby neuroexocytosis is selectively impaired at excitatory synapses, while inhibitory synapses remain functional. This suggests a presynaptic inhibitory mechanism that complements the other inhibitory effects of these drugs.

Impaired excitability of nucleus tractus solitarius neurons in a neonatal rat model of hyperbilirubinemia

Hyperbilirubinemia is associated with multiple morbidities including apnea of prematurity in preterm infants. Bilirubin, a byproduct of hemoglobin breakdown, is not excreted normally and results in high circulating levels giving rise to a state of hyperbilirubinemia. Free bilirubin (not bound to albumin) can cross the blood-brain barrier and be neurotoxic. Prior studies have shown that a systemic injection of bilirubin accumulates in the brainstem and is associated with an impaired ventilatory response to hypercapnia and an augmented hypoxic ventilatory depression. Here, using the Gunn rat model of endogenous hyperbilirubinemia, we investigated its effects on the excitability of neurons of the nucleus tractus solitarius (NTS). The homozygous Gunn rat (jj) model of hyperbilirubinemia lacks uridine diphosphate-glucuronosyltransferase-1A1, an enzyme which is needed to catabolize bilirubin. Heterozygous Nj Gunn rat pups were used for control. On postnatal (P) day 5, Nj and jj rat pups received either a 200mg/kg intraperitoneal injection of sulfadimethoxine (SDMX), which dissociates bilirubin from albumin resulting in increased levels of circulating free bilirubin, or an equivalent amount of saline as a vehicle control. Whole cell patch clamp was performed on NTS neurons two days later (P7) to assess characteristics of evoked excitatory postsynaptic currents (eEPSC).The amplitude of the evoked stimulus response to a 20Hz stimulus train was significantly increased in NTS neurons from jj+saline pups when compared to cells from Nj+saline and Nj+SDMX animals (p<0.05). This increased amplitude was no longer present after SDMX treatment of jj pups. Additionally, jj+saline NTS neurons did not exhibit any failure to solitary tract stimulation, whereas SDMX treatment significantly increased the failure rate during a 20Hz stimulus train (jj+saline =0.0%±0.0, jj+SDMX= 18.63%±8.82, p<0.05). Comparison of failure rate of jj+saline to Nj+saline (6.63%±3.12, p<0.05) was also statistically significant. The hyper-responsive NTS neurons of jj+saline rats may be an adaptive response to the deleterious effects of circulating (bound and unbound) bilirubin. However, the impaired response of neurons in jj+SDMX rats may reflect neurotoxic effects of increased free bilirubin leading to impaired neurotransmission. The latter is consistent with the high failure rate of NTS neurons in jj+SDMX rats. These data may have implications for impaired respiratory control mechanisms involved in mediating essential vagally mediated ventilatory defense responses to hypoxemia and may contribute to the apnea of prematurity associated with hyperbilirubinemia in preterm infants. William and Lois Briggs Endowment. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

THE IMPACT OF EDARAVONE ON THE MARKERS OF CARBONYL-OXIDATIVE STRESS IN RATS WITH TRAUMATIC BRAIN INJURY

In the condition of traumatic brain injury (TBI), the brain develops a series of complex metabolic changes, including protein carbonylation, enhanced lipid peroxidation, impaired neurotransmitter release, and imbalanced energy supply, that are associated with the development of different functional disorders so the search for preventive medications in this pathology is very important. Edaravone is considered a supplementary drug in the treatment of different functional disorders of the central nervous system, but the mechanisms of its protective action remain under question. Aim. This comparative research aimed to study the effects of edaravone on the biomarkers of carbonyl-oxidative stress (COS) in rats with traumatic brain injury. TBI was caused by mechanical damage with a metal weight (450 g) falling from a height of 170 cm. Methods. Advanced oxidation protein products (AOPP), thiobarbituric acid reactive substances, protein carbonyls (PC370/PC430) were studied using spectrophotometry in serum and fraction S1 in brain cortex and hippocampus of experimental animals. Edaravone supplementation may provide significant protection against brain hemorrhagic complications by reducing COS and oxidative modification of proteins. Resylts. In our study, edaravone demonstrated moderate efficacy in reducing serum PC430 and AOPP levels, indicating its ability to attenuate TBI-induced oxidative damage. In addition to its systemic effects, edaravone exerted targeted effects on COS-modified proteins in the hippocampus, even though such biomarkers were not altered significantly by TBI alone. Concluson. Further research is necessary to elucidate the primary mechanisms of action of this drug based on the data obtained.

Substitution of bridge carbons for sulphur in calix[4]arene-bis-α-hydroxymethylphosphonic acid transformed mobile carrier into ionic channel accompanied with evoked muscle contraction and impaired neurotransmission powered by membrane action of resulting thiocalix[4]arene-bis-α-hydroxymethylphosphonic acid

The action of calix[4]arenes C-424, C-425 and C-1193 has been investigated on suspended cholesterol/egg phosphatidylcholine lipid bilayer in a voltage-clamp mode. Comparative analysis with the membrane action by calix[4]arene-bis-α-hydroxymethylphosphonic acid (C-99) has shown that the substitution of bridge carbons for sulphur and addition of another methyl group to two alkyl tales in the lower rim of former dipropoxycalix[4]arene C-99 transformed mobile carrier that C-99 created in lipid bilayer (Shatursky et al., 2014) into a transmembrane pore as exposure of the bilayer membrane to sulphur-containing derivative dibutoxythiocalix[4]arene C-1193 resulted in microscopic transmembrane current patterns indicative of a channel-like mode of facilitated diffusion. Within all calix[4]arenes tested a net steady-state voltage-dependent transmembrane current was readily achieved only after addition of calix[4]-arene C-1193. In comparison with the membrane action of C-99 the current induced by calix[4]-arene C-1193 exhibited a much weakened anion selectivity passing slightly more current at positive potentials applied from the side of bilayer membrane to which the calix[4]-arene was added. Testing C-1193 for the membrane action against smooth muscle cells of rat uterus or swine myometrium and synaptosomes of rat brain nerve terminals revealed an increase in intracellular concentration of Ca2+ with reduction of the effective hydrodynamic diameter of the smooth muscle cells and enhanced basal extracellular level of neurotransmitters (glutamate and γ-aminobutyric acid) after C-1193-induced depolarization of the nerve terminals.

Association between G6PD deficiency and schizophrenia A case report

IntroductionG6PD is essential for the production of NADPH, which is a cofactor for many enzymes involved in antioxidant defense and neurotransmitter synthesis. A deficiency in this enzyme could lead to increased oxidative stress, impaired neurotransmitter and immune function. The latter have been implicated in the pathophysiology of schizophrenia.ObjectivesThe present case is presented to underscore the infrequent and uncharacteristic manifestation of this condition, in the context of clinical symptoms and the trajectory of evolution of schizophrenia when associated with G6PD Deficiency. Moreover, it sheds light on the challenges clinicians encounter in the management of such cases.MethodsA case report of a patient who was admitted to the Psychiatry Department (“Ibn Omrane”) of Razi Hospital”.ResultsMr. M.T is a 26 year-old unmarried man. He comes from a non-consanguineous marriage and has an educational level of a bachelor’s degree plus three additional years of study. He has a significant family medical history. His maternal uncle is under treatment for a chronic psychotic disorder. He has a personal history of G6PD deficiency and no specific habits to note. At the age of 24, he insidiously developed anxiety with incoherent statements of persecution accompanied by behavioral manifestations leading to mistrust and social isolation. He discontinued his studies for a year and began verbalizing suicidal thoughts accompanied by self-harm behaviors.The family sought help from a psychiatrist who prescribed 5 mg of olanzapine, which was covertly administered to the patient.At the age of 28, after a suicide attempt, he was involuntarily admitted to Razi Hospital. The clinical presentation was dominated by disorganization, with a partial response to treatment.ConclusionsMore research is needed to confirm the association between G6PD deficiency and schizophrenia and to determine the underlying mechanisms. Larger studies with well-defined populations and methodologies are needed. It is also important to study the interaction between G6PD deficiency and other genetic and environmental factors that contribute to schizophrenia.Disclosure of InterestNone Declared

Pharmacological enhancement of cholinergic neurotransmission alleviates neuroinflammation and improves functional outcomes in a triple transgenic mouse model of Alzheimer's disease.

Introduction: Alzheimer's disease (AD) is the most common neurodegenerative disorder affecting the elderly population worldwide. Due to the multifactorial nature of the disease, involving impairment of cholinergic neurotransmission and immune system, previous attempts to find effective treatments have faced challenges. Methods: In such scenario, we attempted to investigate the effects of alpha-glyceryl-phosphoryl-choline (α-GPC), a cholinomimetic molecule, on neuroinflammation and memory outcome in the triple transgenic mouse model of AD (3xTg-AD). Mice were enrolled at 4 months of age, treated orally with α-GPC dissolved in drinking water at a concentration resulting in an average daily dose of 100mg/kg for 8 months and sacrificed at 12 months of age. Thereafter, inflammatory markers, as well as cognitive parameters, were measured. Results: Chronic α-GPC treatment reduced accumulation of amyloid deposits and led to a substantial re-balance of the inflammatory response of resident innate immune cells, astrocytes and microglia. Specifically, fluorescent immunohistochemistry and Western blot analysis showed that α-GPC contributed to reduction of cortical and hippocampal reactive astrocytes and pro-inflammatory microglia, concurrently increasing the expression of anti-inflammatory molecules. Whereas α-GPC beneficially affect the synaptic marker synaptophysin in the hippocampus. Furthermore, we observed that α-GPC was effective in restoring cognitive dysfunction, as measured by the Novel Object Recognition test, wherein 3xTg-AD mice treated with α-GPC significantly spent more time exploring the novel object compared to 3xTg-AD untreated mice. Discussion: In conclusion, chronic treatment with α-GPC exhibited a significant anti-inflammatory activity and sustained the key function of hippocampal synapses, crucial for the maintenance of a regular cognitive status. In light of our results, we suggest that α-GPC could be exploited as a promising therapeutic approach in early phases of AD.

Molecular Mechanisms Linking Osteoarthritis and Alzheimer's Disease: Shared Pathways, Mechanisms and Breakthrough Prospects.

Alzheimer's disease (AD) is a progressive neurodegenerative disease mostly affecting the elderly population. It is characterized by cognitive decline that occurs due to impaired neurotransmission and neuronal death. Even though deposition of amyloid beta (Aβ) peptides and aggregation of hyperphosphorylated TAU have been established as major pathological hallmarks of the disease, other factors such as the interaction of genetic and environmental factors are believed to contribute to the development and progression of AD. In general, patients initially present mild forgetfulness and difficulty in forming new memories. As it progresses, there are significant impairments in problem solving, social interaction, speech and overall cognitive function of the affected individual. Osteoarthritis (OA) is the most recurrent form of arthritis and widely acknowledged as a whole-joint disease, distinguished by progressive degeneration and erosion of joint cartilage accompanying synovitis and subchondral bone changes that can prompt peripheral inflammatory responses. Also predominantly affecting the elderly, OA frequently embroils weight-bearing joints such as the knees, spine and hips leading to pains, stiffness and diminished joint mobility, which in turn significantly impacts the patient's standard of life. Both infirmities can co-occur in older adults as a result of independent factors, as multiple health conditions are common in old age. Additionally, risk factors such as genetics, lifestyle changes, age and chronic inflammation may contribute to both conditions in some individuals. Besides localized peripheral low-grade inflammation, it is notable that low-grade systemic inflammation prompted by OA can play a role in AD pathogenesis. Studies have explored relationships between systemic inflammatory-associated diseases like obesity, hypertension, dyslipidemia, diabetes mellitus and AD. Given that AD is the most common form of dementia and shares similar risk factors with OA-both being age-related and low-grade inflammatory-associated diseases, OA may indeed serve as a risk factor for AD. This work aims to review literature on molecular mechanisms linking OA and AD pathologies, and explore potential connections between these conditions alongside future prospects and innovative treatments.

Membranes and Synaptosomes Used to Investigate Synaptic GABAergic Currents in Epileptic Patients.

Among the most prevalent neurological disorders, epilepsy affects about 1% of the population worldwide. We previously found, using human epileptic tissues, that GABAergic neurotransmission impairment is a key mechanism that drives the pathological phenomena that ultimately lead to generation and recurrence of seizures. Using both a "microtransplantation technique" and synaptosomes preparations from drug-resistant temporal lobe epilepsies (TLEs), we used the technique of two-electrode voltage clamp to record GABA-evoked currents, focusing selectively on the synaptic "fast inhibition" mediated by low-affinity GABAA receptors. Here, we report that the use-dependent GABA current desensitization (i.e., GABA rundown, which is evoked by applying to the cells consecutive pulses of GABA, at high concentration), which is a distinguishing mark of TLE, is mainly dependent on a dysfunction that affects synaptic GABAA receptors. In addition, using the same approaches, we recorded a depolarized GABA reversal potential in synaptosomes samples from the human epileptic subicula of TLE patients. These results, which confirm previous experiments using total membranes, suggest an altered chloride homeostasis in the synaptic area. Finally, the lack of a Zn2+ block of GABA-evoked currents using the synaptosomes supports the enrichment of "synaptic fast inhibitory" GABAA receptors in this preparation. Altogether, our findings suggest a pathophysiological role of low-affinity GABAA receptors at the synapse, especially during the fast and repetitive GABA release underlying recurrent seizures.

Human mutations in SLITRK3 implicated in GABAergic synapse development in mice.

This study reports on biallelic homozygous and monoallelic de novo variants in SLITRK3 in three unrelated families presenting with epileptic encephalopathy associated with a broad neurological involvement characterized by microcephaly, intellectual disability, seizures, and global developmental delay. SLITRK3 encodes for a transmembrane protein that is involved in controlling neurite outgrowth and inhibitory synapse development and that has an important role in brain function and neurological diseases. Using primary cultures of hippocampal neurons carrying patients' SLITRK3 variants and in combination with electrophysiology, we demonstrate that recessive variants are loss-of-function alleles. Immunostaining experiments in HEK-293 cells showed that human variants C566R and E606X change SLITRK3 protein expression patterns on the cell surface, resulting in highly accumulating defective proteins in the Golgi apparatus. By analyzing the development and phenotype of SLITRK3 KO (SLITRK3-/-) mice, the study shows evidence of enhanced susceptibility to pentylenetetrazole-induced seizure with the appearance of spontaneous epileptiform EEG as well as developmental deficits such as higher motor activities and reduced parvalbumin interneurons. Taken together, the results exhibit impaired development of the peripheral and central nervous system and support a conserved role of this transmembrane protein in neurological function. The study delineates an emerging spectrum of human core synaptopathies caused by variants in genes that encode SLITRK proteins and essential regulatory components of the synaptic machinery. The hallmark of these disorders is impaired postsynaptic neurotransmission at nerve terminals; an impaired neurotransmission resulting in a wide array of (often overlapping) clinical features, including neurodevelopmental impairment, weakness, seizures, and abnormal movements. The genetic synaptopathy caused by SLITRK3 mutations highlights the key roles of this gene in human brain development and function.

Screening for new ligands of the MB327-PAM-1 binding site of the nicotinic acetylcholine receptor

Intoxications with organophosphorus compounds (OPCs) effect a severe impairment of cholinergic neurotransmission that, as a result of overstimulation may lead to desensitization of nicotinic acetylcholine receptors (nAChRs) and finally to death due to respiratory paralysis. So far, therapeutics, that are capable to address and revert desensitized neuromuscular nAChRs into their resting, i.e. functional state are still missing. Still, among a class of compounds termed bispyridinium salts, which are characterized by the presence of two pyridinium subunits, constituents have been identified, that can counteract organophosphate poisoning by resensitizing desensitized nAChRs. According to comprehensive modeling studies this effect is mediated by an allosteric binding site at the nAChR termed MB327-PAM-1 site. For MB327, the most prominent representative of the bispyridinium salts and all other analogues studied so far, the affinity for the aforementioned binding site and the intrinsic activity measured in ex vivo and in in vivo experiments are distinctly too low, to meet the criteria to be fulfilled for therapeutic use. Hence, in order to identify new compounds with higher affinities for the MB327-PAM-1 binding site, as a basic requirement for an enhanced potency, two compound libraries, the ChemDiv library with 60 constituents and the Tocriscreen Plus library with 1280 members have been screened for hit compounds addressing the MB327-PAM-1 binding site, utilizing the [2H6]MB327 MS Binding Assay recently developed by us. This led to the identification of a set of 10 chemically diverse compounds, all of which exhibit an IC50 value of ≤ 10 µM (in the [2H6]MB327 MS Binding Assay), which had been defined as selection criteria. The three most affine ligands, which besides a quinazoline scaffold share similarities with regard to the substitution pattern and the nature of the substituents, are UNC0638, UNC0642 and UNC0646. With binding affinities expressed as pKi values of 6.01 ± 0.10, 5.97 ± 0.05 and 6.23 ± 0.02, respectively, these compounds exceed the binding affinity of MB327 by more than one log unit. This renders them promising starting points for the development of drugs for the treatment of organophosphorus poisoning by addressing the MB327-PAM-1 binding site of the nAChR.

Apple Pomace Extract Improves MK-801-Induced Memory Impairment in Mice.

Alzheimer's disease (AD) is a neurodegenerative disease that involves progressive cognitive decline accompanied by synaptic degeneration and impaired neurotransmission. Recent studies revealed that apple pomace, a waste byproduct of the apple processing industry, has beneficial health properties, but its potential to prevent and treat AD has not been determined. Herein, we examined the effects of apple pomace extract on N-methyl-D-aspartate receptor antagonist MK-801-induced memory impairment in mice. Repeated treatment with apple pomace extract for 7 days reversed the MK-801-induced impairment of associative memory and recognition memory. RNA sequencing revealed that repeated treatment with apple pomace extract altered the gene expression profile in the hippocampus of mice. Real-time PCR showed that apple pomace extract induced upregulation of the mRNA expression for Zfp125 and Gstp1. Furthermore, gene sets related to synapse and neurotransmission were upregulated by apple pomace extract. These findings indicate that apple pomace extract may be useful for the prevention and treatment of AD.

In vivo and in silico toxicity assessment of four common liquid crystal monomers to Daphnia magna: Novel endocrine disrupting chemicals in crustaceans?

Liquid crystal monomers (LCMs) are widely used in liquid crystal displays (LCDs) and are proposed to be a new generation of environmentally persistent, bioaccumulative and toxic (PBT) substances that are increasingly detected in rivers and seas. However, there is a lack of in vivo data that characterize adverse responses and toxic mechanisms of LCMs on aquatic organisms. The aim of this study was to comprehensively investigate the effect of four typical LCMs on the lethality, growth, molting, and reproductive capacity of Daphnia magna (D. magna), a highly studied aquatic species in environmental toxicology. Whole body and enzymatic biomarkers (i.e., body length, chitobiase, acetylcholinesterase, antioxidant defense) were measured to assess the toxicity of LCMs. The 48 h mortality rate and observations of disrupted thorax development and inhibition of ecdysis indicate that D. magna are sensitive to LCMs exposure. Oxidative stress, impaired neurotransmission, and disruptions in molting were observed in short-term biomarker tests using LCMs. A 21 day exposure of D. magna to LCMs resulted in reduced growth, reproduction, and population intrinsic growth rate. In addition, chitobiase and 20-hydroxyecdysone, enzymes important for the molting process, were altered at 7, 14 and 21 d. This is hypothesized to be related to endocrine imbalance resulting from LCM exposure. Based on molecular docking simulations, there is evidence that LCMs bind directly to ecdysteroid receptors; this may explain the observed endocrine disrupting effects of LCMs. These data support the hypothesis that LCMs are endocrine disrupting chemicals in aquatic species, impacting the process of molting. This may subsequently lead to lower reproduction and unbalanced population dynamics.

Alteration of redox status and fatty acid profile in gills from the green crab (Carcinus aestuarii) following dimethoate exposure

Dimethoate is a broad-spectrum organophosphate insecticide and acaricide. Through various pathways, such as runoff and drift, dimethoate can reach marine environment, and easily impact common organisms in coastal areas, close to agriculture lands, namely crustaceans. The purpose of this study was to investigate the potential effects of dimethoate exposure (50, 100, and 200 μg/l), for 1 day, on a wide range of markers of oxidative stress and neurotransmission impairment, as well as fatty acids composition and histopathological aspect in the gills of the green crab Carcinus aestuarii. A significant increase in n-3 polyunsaturated fatty acids series, namely the eicosapentaenoic acid (C20: 5n3) and its precursor alpha-linolenic acid (C 18: 3n3) in dimethoate-treated crabs was recorded. Concerning n-6 polyunsaturated fatty acids, we noted a high reduction in arachidonic acid (C20:4n-6) levels. Dimethoate exposure increased the levels of hydrogen peroxide, malondialdehyde, lipid hydroperoxides, protein carbonyl, and caused the advanced oxidation of protein products along with enzymatic and non-enzymatic antioxidant-related markers. Acetylcholinesterase activity was highly inhibited following exposure to dimethoate in a concentration-dependent manner. Finally, deleterious histopathological changes with several abnormalities were noted in exposed animals confirming our biochemical findings. The present study offered unique insights to establish a relationship between redox status and alterations in fatty acid composition, allowing a better understanding of dimethoate-triggered toxicity.