Maja Stojković

The full mutation and epigenetic silencing of the FMR1 gene lead to a deficiency of its protein, FMRP, resulting in Fragile X Syndrome (FXS). Although significant advances have been made in understanding the molecular mechanisms underlying FXS, no cure or targeted pharmacological treatments have yet been approved for this neurodevelopmental disorder. Current clinical management primarily relies on symptomatic therapies, which often offer limited benefits and do not address the core molecular causes of the condition, especially given the multifaceted roles of the FMRP. This review highlights the crucial role of molecular insights in guiding the development of drugs for FXS. It provides an overview of existing pharmacotherapies, discusses their benefits and limitations, and emphasizes the unmet need for interventions that target the specific pathways disrupted by FMR1 dysfunction. Recent and ongoing clinical trials were examined, focusing on how a deeper understanding of FXS molecular biology can inform the design of more effective and precise therapeutic strategies. In summary, key molecular pathways relevant to FXS are presented, and the potential synergy between clinical pharmacology and molecular medicine is discussed as a means to promote the advancement of tailored therapeutic approaches.

Background: The active ingredients of essential plant oils appear as potentially effective antinematodal drugs or substances that can potentiate the action of already-existing anthelmintics. So far, we have verified that, aside from the direct effect on the neuromuscular system of nematodes, some of them can potentiate the effects of drugs that are agonists or antagonists of nematode cholinergic receptors. Methods: In this study, the antinematodal effects of geraniol and carvacrol were compared, as well as their interaction in the experimental model Caenorhabditis elegans, on the contractile properties of Ascaris suum neuromuscular preparations and on the ACR-16 nicotinic acetylcholine receptor (nAChR) of A. suum expressed in Xenopus leavis oocytes. Results: The combination of geraniol and carvacrol showed a synergistic nematocidal effect in the tests on C. elegans, reducing the value of individual LC₅₀ by almost 10-times. This combination also exerted a synergistic inhibitory effect on the contractions of A. suum, significantly increased the EC₅₀ of ACh and reduced the maximal contractile effect. The synergistic interaction of these two monoterpenes on Asu-ACR-16 nAChR expressed in Xenopus oocytes resulted in a significant decrease in the maximum current, while the ACh EC₅₀ value remained unchanged. Conclusions: Our findings provide a better understanding of the mode of action of monoterpene plant compounds. The possible antiparasitic application of active ingredients of essential plant oils that exhibit a synergistic anthelmintic effect represents an important basis for the development of new drugs and new therapeutic procedures.

Background: The active ingredients of essential plant oils appear as potentially effective antinemtodal drugs or substances that can potentiate the action of already existing anthelmintics. So far, we have verified that, aside from the direct effect on the neuromuscular system of nematodes (by inhibiting or potentiating contractility), some of them can potentiate the effects of drugs that are agonists or antagonists of nematode cholinergic receptors. Methods: In this study the antinematodal effects of geraniol and carvacrol was compared, as well as their interaction in the experimental model Caenorhabditis elegans, on the contractile properties of Ascaris suum neuromuscular preparations and on the ACR-16 nicotinic acetylcholine receptor (nAChR) of A. suum expressed in Xenopus leavis oocytes. Results: Combination of geraniol and carvacrol, showed a synergistic nematocidal effect in the tests on C. elegans, reducing the value of individual LC50 for almost 10 times. This combination also exerted a synergistic inhibitory effect on the contractions of A. suum, and significantly increased the EC50 of ACh and reduced the maximal contractile effect. The synergistic interaction of these two monoterpenes on Asu-ACR-16 nAChR expressed in Xenopus oocytes resulted in a significant decrease of the maximum current while the ACh EC50 value remained unchanged. Conclusions: Our findings bring a better understanding on the mode of action of monoterpene plant compounds. The possible application of active ingredients of essential plant oils that exhibit a synergistic anthelmintic effect represents an important basis for the development of new drugs and new therapeutic procedures.

Neurodevelopmental disorders (NDDs), including autism spectrum disorder (ASD), attention-deficit/hyperactivity disorder (ADHD), and other cognitive and behavioral impairments, are increasing globally, placing significant burdens on individuals and healthcare systems. Traditional therapeutic strategies, primarily pharmacologic and behavioral, offer limited efficacy and often fail to address the multifactorial etiology of these conditions. Recent advances in microbiome research highlight the gut microbiota as a potential modulator of brain function via the microbiota-gut-brain axis (MGBA). This bidirectional network influences neurodevelopment through neural, immune, endocrine, and metabolic pathways. Dysbiosis, or microbial imbalance, has been consistently reported in individuals with NDDs, particularly in ASD and ADHD, correlating with symptom severity and gastrointestinal comorbidities. Emerging interventions aimed at restoring microbial balance, such as probiotics, prebiotics, synbiotics, faecal microbiota transplantation (FMT), and dietary modifications – demonstrate potential in modulating behaviour and cognition. However, the current evidence is limited by small sample sizes, heterogeneous methodologies, and a lack of long-term follow-up. This mini-review synthesizes current findings on the role of gut microbiome modulation in NDDs, evaluates the therapeutic efficacy of microbiome-based interventions, and discusses future directions, including personalized microbiome-targeted strategies and the need for robust randomized controlled trials.

Muscarinic acetylcholine receptors (mAChRs) are a subfamily of G protein-coupled receptors that have been identified as promising targets for drug development. Five different mAChR subtypes regulate various fundamental functions. In the central nervous system (CNS), they play a crucial role in regulating numerous cognitive, behavioral, and autonomic functions. Outside the CNS, they facilitate the effects of acetylcholine in organs and tissues innervated by parasympathetic nerves, participating in various vegetative functions such as regulating heart rate, smooth muscle contraction, and glandular secretion. The disruption in cholinergic signalling contributes to several pathophysiological conditions and diseases. Thus, muscarinic agonists and antagonists have a wide therapeutic potential in the treatment of neuropsychiatric disorders, such as Alzheimer's disease, schizophrenia or pain, and also in diseases like COPD and incontinence. Activation of different mAChR with selective ligands could be beneficial for treating the above-mentioned diseases while avoiding side effects. Clinical trials targeting mAChRs have shown promising results, with several compounds demonstrating efficacy and better tolerability profiles. However, developing drugs targeting mAChR still presents challenges, primarily due to the high homology in the structure of the orthosteric binding site. The recent insights into the physiology, pharmacology, and structure of mAChRs have provided opportunities for the development of novel drugs targeting these receptors, including allosteric modulators. Allosteric modulators offer the advantage of selective binding mAChR, potentially enhancing therapeutic efficacy while minimizing off-target effects. In conclusion, mAChRs represent promising targets for drug development. Further research and clinical trials are needed to develop effective therapies targeting muscarinic receptors for various diseases.

Fragile X syndrome (FXS) is caused by the full mutation in the FMR1 gene on the Xq27.3 chromosome region. It is the most common monogenic cause of autism spectrum disorder (ASD) and inherited intellectual disability (ID). Besides ASD and ID and other symptoms, individuals with FXS may exhibit sleep problems and impairment of circadian rhythm (CR). The Drosophila melanogaster models of FXS, such as dFMR1^B55, represent excellent models for research in the FXS field. During this study, sleep patterns and CR in dFMR1^B55 mutants were analyzed, using a new platform based on continuous high-resolution videography integrated with a highly-customized version of an open-source software. This methodology provides more sensitive results, which could be crucial for all further research in this model of fruit flies. The study revealed that dFMR1^B55 male mutants sleep more and can be considered weak rhythmic flies rather than totally arrhythmic and present a good alternative animal model of genetic disorder, which includes impairment of CR and sleep behavior. The combination of affordable videography and software used in the current study is a significant improvement over previous methods and will enable broader adaptation of such high-resolution behavior monitoring methods.

Fragile X syndrome (FXS), the most common monogenic cause of inherited intellectual disability and autism spectrum disorder, is caused by a full mutation (>200 CGG repeats) in the Fragile X Messenger Ribonucleoprotein 1 (FMR1) gene. Individuals with FXS experience various challenges related to social interaction (SI). Animal models, such as the Drosophila melanogaster model for FXS where the only ortholog of human FMR1 (dFMR1) is mutated, have played a crucial role in the understanding of FXS. The aim of this study was to investigate SI in the dFMR1^B55 mutants (the groups of flies of both sexes simultaneously) using the novel Drosophila Shallow Chamber and a Python data processing pipeline based on social network analysis (SNA). In comparison with wild-type flies (w¹¹¹⁸), SNA analysis in dFMR1^B55 mutants revealed hypoactivity, fewer connections in their networks, longer interaction duration, a lower ability to transmit information efficiently, fewer alternative pathways for information transmission, a higher variability in the number of interactions they achieved, and flies tended to stay near the boundaries of the testing chamber. These observed alterations indicate the presence of characteristic strain-dependent social networks in dFMR1^B55 flies, commonly referred to as the group phenotype. Finally, combining novel research tools is a valuable method for SI research in fruit flies.

Fragile X syndrome (FXS) is caused by the full mutation in the FMR1 gene on the Xq27.3 chromosome region. It is the most common monogenic cause of Autism Spectrum Disorder (ASD) and inherited intellectual disability (ID). Besides ASD, ID and other issues, individuals with FXS may exhibit sleep problems and impairment of circadian rhythm (CR). The Drosophila melanogaster models of FXS, such as dFMR1B55, present excellent model for research in the FXS field. During this study, sleep pattern and CR in dFMR1B55 mutants were analyzed, using a new platform based on continuous high-resolution videography in integration with a highly-customized version of software. This methodology provides more sensitive results, which could be crucial for all further research in this model of fruit flies. The study revealed that dFMR1 B55 male mutants can be considered weak rhythmic flies rather than totally arrhythmic, and present a good alternative animal model of genetic disorder, which includes impairment of CR and sleep behavior. The combination of videography and software used in the current study should be recommended as a gold-standard methodology for such further research.

Fragile X syndrome (FXS), the most common monogenic cause of inherited intellectual disability and autism spectrum disorder, is caused by a full mutation (>200 CGG repeats) in the Fragile X Messenger Ribonucleoprotein 1 (FMR1) gene. Individuals with FXS experience a wide range of challenges related to social interaction (SI). Animal models, such as Drosophila melanogaster model for FXS where the only ortholog of human FMR1 (dFMR1) is mutated, have played a crucial role in understanding of FXS. The aim of this study was to investigate SI in the dFMR1B55 mutants using the novel Drosophila Shallow Chamber and a Python data processing pipeline based on social network analysis (SNA). In comparison with wild-type flies (w1118), SNA analysis in dFMR1B55 mutants revealed hypoactivity, fewer connections in their networks, a lower ability to efficiently transmit information, fewer alternative pathways for information transmission, a higher variability in the number of interactions they achieved, and tended to stay near the boundaries of the testing chamber. These observed alterations indicate the presence of characteristic strain-dependent social networks in dFMR1B55 flies, commonly referred to as the group phenotype. Finally, a combination of novel research tools is a valuable method for SI research in fruit flies.

Introduction: Fragile X syndrome (FXS) is the most common monogenetic cause of intellectual disability (ID) and autism spectrum disorder (ASD) in humans. The Drosophila melanogaster model of FXS (dFMR1 mutants) is an excellent model for research in the field of FXS. The aim of this study was a comprehensive investigation of climbing abilities, as a measurement of locomotion, in the dFMR1B55 line as a Drosophila model of FXS. Methods: In this study, control w1118 and dFMR1B55 lines of fruit flies were used. The climbing performance of flies was examined using a climbing performance assay for groups of flies as well as for individual flies. Parameters that represent climbing ability, speed and endurance were determined. Females and males were analyzed separately. Results: This study revealed the following: (i) worse climbing performance of dFMR1B55 males in comparison to w1118 males; (ii) worse climbing success of dFMR1B55 females in comparison to w1118 females; (iii) better climbing performance of top performer males in comparison to top performer females in the group climbing test in both dFMR1B55 and w1118 groups; (iv) better, but not statistically significant, climbing performance (based on the time needed for 50% of flies to complete the task), and a higher success rate in dFMR1B55 females in comparison to dFMR1B55 males. Conclusion: According to the results of the current study, climbing impairment was proved only in dFMR1B55 males, while dFMR1B55 females had climbing abilities similar to control w1118 females.