S-adenosyl methionine improves motor co-ordination with reduced oxidative stress, dopaminergic neuronal loss, and DNA methylation in the brain striatum of 6-hydroxydopamine-induced neurodegeneration in rats

Natural sulfur compounds in mental health and neurological disorders: insights from observational and intervention studies

Over the years, the global disease burden of neurological disorders (NDs) and mental disorders (MDs) has significantly increased, making them one of the most critical concerns and challenges to human health. In pursuit of novel therapies against MD and ND, there has been a growing focus on nutrition and health. Dietary sulfur, primarily derived from various natural sources, plays a crucial role in numerous physiological processes, including brain function. This review offers an overview of the chemical composition of several natural sources of the sulfur-rich substances such as isothiocyanates, sulforaphane, glutathione, taurine, sulfated polysaccharides, allyl sulfides, and sulfur-containing amino acids, all of which have neuroprotective properties. A multitude of studies have documented that consuming foods that are high in sulfur enhances brain function by improving cognitive parameters and reduces the severity of neuropathology by exhibiting antioxidant and anti-inflammatory properties at the molecular level. In addition, the growing role of natural sulfur compounds in repairing endothelial dysfunction, compromising blood-brain barrier and improving cerebral blood flow, are documented here. Furthermore, this review covers the encouraging results of supplementing sulfur-rich diets in many animal models and clinical investigations, along with their molecular targets in MD, such as schizophrenia, depression, anxiety, bipolar disorder, and autism spectrum disorder, and ND, such as Alzheimer's disease (AD), Parkinson's disease (PD), Amyotrophic Lateral Sclerosis (ALS), and Multiple Sclerosis (MS). The prospects of natural sulfur compounds show great promise as they have potential applications in nutraceuticals, medicines, and functional foods to enhance brain function and prevent diseases. However, additional research is required to clarify the mechanisms by which it works, enhance its bioavailability, and evaluate its long-term safety for broad use.

Prepubertal phthalate exposure can cause histopathological alterations, DNA methylation and histone acetylation changes in rat brain

Di-2-(ethylhexyl)phthalate (DEHP) is a phthalate derivative used extensively in a wide range of materials, such as medical devices, toys, cosmetics, and personal care products. Many mechanisms, including epigenetics, may be involved in the effects of phthalates on brain development. In this study, Sprague-Dawley male rats were obtained 21-23 days after their birth (post-weaning) and were exposed to DEHP during the prepubertal period with low-dose DEHP (DEHP-L, 30 mg/kg/day) and high-dose DEHP (DEHP-H, 60 mg/kg/day, 37 days) until the end of adolescence (PND 60). The rats in the study groups were sacrificed during adulthood, and histopathological changes, epigenetic changes, and oxidative stress parameters were evaluated in brain tissues. Histopathological findings indicating the presence of deterioration in brain tissue morphology were obtained, more prominently in the DEHP-H group. Examining the hippocampus under the light microscope, pyramidal neuron loss was detected only in CA1 of the DEHP-L group, while in DEHP-H rats, pyramidal neuron losses were detected in the CA1, CA2, and CA3 regions. No significant change was observed in brain lipid peroxidation levels with DEHP compared to control. Significant increases in total glutathione (GSH) in both dose groups were considered to be an adaptive response to DEHP-induced oxidative stress. The decrease in DNA methylation in the brain, although not statistically significant, and the increase in histone modification showed that exposure to DEHP may cause epigenetic changes in the brain and these epigenetic changes may also take place as one of the mechanisms underlying the damage observed in the brain. The results suggest that DEHP exposure during early development may have a significant effect on brain development.

Oleuropein enhances proteasomal activity and reduces mutant huntingtin-induced cytotoxicity

Introduction

Huntington's disease (HD) is a hereditary neurodegenerative disorder that primarily affects the striatum, a brain region responsible for movement control. The disease is characterized by the mutant huntingtin (mHtt) proteins with an extended polyQ stretch, which are prone to aggregation. These mHtt aggregates accumulate in neurons and are the primary cause of the neuropathology associated with HD. To date, no effective cure for HD has been developed.

Methods

The immortalized STHdh Q111/Q111 striatal cell line, the mHtt-transfected wild-type STHdh Q7/Q7 striatal cell line, and N2a cells were used as Huntington's disease cell models. Flow cytometry was used to assess cellular reactive oxygen species and transfection efficiency. The CCK-8 assay was used to measure cell viability, while fluorescence microscopy was used to quantify aggregates. Immunoblotting analyses were used to evaluate the effects on protein expression.

Results

Polyphenols are natural antioxidants that offer neuroprotection in neurological disorders. In this study, we provide evidence that oleuropein, the primary polyphenol in olive leaves and olive oil, enhances cell viability in HD cell models, including. STHdh Q7/Q7 STHdh Q7/Q7 striatal cells, N2a cells ectopically expressing the truncated mHtt, and STHdh Q111/Q111 striatal cells expressing the full-length mHtt. Oleuropein effectively reduced both soluble and aggregated forms of mHtt protein in these HD model cells. Notably, the reduction of mHtt aggregates associated with oleuropein was linked to increased proteasome activity rather than changes in autophagic flux. Oleuropein seems to modulate proteasome activity through an unidentified pathway, as it did not affect the 20S proteasome catalytic β subunits, the proteasome regulator PA28γ, or multiple MAPK pathways.

Discussion

We demonstrated that oleuropein enhances the degradation of mHtt by increasing proteasomal protease activities and alleviates mHtt-induced cytotoxicity. Hence, we propose that oleuropein and potentially other polyphenols hold promise as a candidate for alleviating Huntington's disease.

Cardioprotective effect of S-adenosyl L-methionine due to antioxidant and anti-inflammatory properties on isoproterenol-induced chronic heart failure in Wistar rats

OBJECTIVES

The development and progression of chronic heart failure (CHF), hypertrophy, and remodeling strongly correlate with myocardial inflammation and oxidative stress. S-adenosylmethionine (SAMe), available as a dietary supplement, exerts anti-inflammatory and antioxidant effects. Previous reports show that by regulating angiogenesis and fibrosis, S-adenosyl-L-methionine improves ventricular remodeling. The study objectives were to investigate the cardioprotective effect of SAMe in isoproterenol (ISO)-induced CHF and explore the anti-inflammatory and antioxidant properties of SAMe in this model.

METHODOLOGY

After animal ethics permission, CHF was induced using ISO of 10 mg/kg for 14 consecutive days in 24 Wistar rats. There were four groups of six rats in each group: Sham Control, Disease Control (DC), ISO + SAMe 100 mg, and ISO + SAMe 200 mg. The variables assessed were heart to body weight ratio (HW/BW mg/g), bio-distribution of Flourine 18-Fluorodeoxyglucose (18F-FDG) in heart tissue, tumor necrosis factor-α (TNF-α) and glutathione (GSH) levels in heart tissue, histopathology, and positron emission tomography imaging.

RESULTS

SAMe in ISO-induced CHF animals showed a significant decrease in the HW/BW compared to DC group (P < 0.001). 18F-FDG uptake was significantly reduced by SAMe in CHF-induced rats compared to DC rats for both doses (P < 0.001). SAMe showed significantly better values of both TNF-α and GSH than the DC group in both doses (P < 0.001). SAMe in both doses showed multifocal necrosis with scarring and minimal inflammatory cells.

CONCLUSION

SAMe exerts a cardioprotective effect on ISO-induced CHF in rats because of its antioxidant and anti-inflammatory properties.

Single-neuron neurodegeneration as a degenerative model for Parkinson's disease

The positive effect of levodopa in the treatment of Parkinson's disease, although it is limited in time and has severe side effects, has encouraged the scientific community to look for new drugs that can stop the neurodegenerative process or even regenerate the neuromelanin-containing dopaminergic nigrostriatal neurons. Successful preclinical studies with coenzyme Q10, mitoquinone, isradipine, nilotinib, TCH346, neurturin, zonisamide, deferiprone, prasinezumab, and cinpanemab prompted clinical trials. However, these failed and after more than 50 years levodopa continues to be the key drug in the treatment of the disease, despite its severe side effects after 4-6 years of chronic treatment. The lack of translated successful results obtained in preclinical investigations based on the use of neurotoxins that do not exist in the human body as new drugs for Parkinson's disease treatment is a big problem. In our opinion, the cause of these failures lies in the experimental animal models involving neurotoxins that do not exist in the human body, such as 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine and 6-hydroxydopamine, that induce a very fast, massive and expansive neurodegenerative process, which contrasts with the extremely slow one of neuromelanin-containing dopaminergic neurons. The exceedingly slow progress of the neurodegenerative process of the nigrostriatal neurons in idiopathic Parkinson's patients is due to (i) a degenerative model in which the neurotoxic effect of an endogenous neurotoxin affects a single neuron, (ii) a neurotoxic event that is not expansive and (iii) the fact that the neurotoxin that triggers the neurodegenerative process is produced inside the neuromelanin-containing dopaminergic neurons. The endogenous neurotoxin that fits this degenerative model involving one single neuron at a time is aminochrome, since it (i) is generated within neuromelanin-containing dopaminergic neurons, (ii) does not cause an expansive neurotoxic effect and (iii) triggers all the mechanisms involved in the neurodegenerative process of the nigrostriatal neurons in idiopathic Parkinson's disease. In conclusion, based on the hypothesis that the neurodegenerative process of idiopathic Parkinson's disease corresponds to a single-neuron neurodegeneration model, we must search for molecules that increase the expression of the neuroprotective enzymes DT-diaphorase and glutathione transferase M2-2. It has been observed that the activation of the Kelch-like ECH-associated protein 1/nuclear factor (erythroid-derived 2)-like 2 pathway is associated with the transcriptional activation of the DT-diaphorase and glutathione transferase genes.

Exploratory focused pharmacogenetic testing reveals novel markers associated with risperidone pharmacokinetics in Saudi children with autism

Background: Autism spectrum disorders (ASDs) encompass a broad range of phenotypes characterized by diverse neurological alterations. Genomic studies have revealed considerable overlap between the molecular mechanisms implicated in the etiology of ASD and genes involved in the pharmacokinetic (PK) and pharmacodynamic (PD) pathways of antipsychotic drugs employed in ASD management. Given the conflicting data originating from candidate PK or PD gene association studies in diverse ethnogeographic ASD populations, dosage individualization based on "actionable" pharmacogenetic (PGx) markers has limited application in clinical practice. Additionally, off-label use of different antipsychotics is an ongoing practice, which is justified given the shortage of approved cures, despite the lack of satisfactory evidence for its safety according to precision medicine. This exploratory study aimed to identify PGx markers predictive of risperidone (RIS) exposure in autistic Saudi children. Methods: This prospective cohort study enrolled 89 Saudi children with ASD treated with RIS-based antipsychotic therapy. Plasma levels of RIS and 9-OH-RIS were measured using a liquid chromatography-tandem mass spectrometry system. To enable focused exploratory testing, genotyping was performed with the Axiom PharmacoFocus Array, which included a collection of probe sets targeting PK/PD genes. A total of 720 PGx markers were included in the association analysis. Results: A total of 27 PGx variants were found to have a prominent impact on various RIS PK parameters; most were not located within the genes involved in the classical RIS PK pathway. Specifically, 8 markers in 7 genes were identified as the PGx markers with the strongest impact on RIS levels (p < 0.01). Four PGx variants in 3 genes were strongly associated with 9-OH-RIS levels, while 5 markers in 5 different genes explained the interindividual variability in the total active moiety. Notably, 6 CYP2D6 variants exhibited strong linkage disequilibrium; however, they significantly influenced only the metabolic ratio and had no considerable effects on the individual estimates of RIS, 9-OH-RIS, or the total active moiety. After correction for multiple testing, rs78998153 in UGT2B17 (which is highly expressed in the brain) remained the most significant PGx marker positively adjusting the metabolic ratio. For the first time, certain human leukocyte antigen (HLA) markers were found to enhance various RIS exposure parameters, which reinforces the gut-brain axis theory of ASD etiology and its suggested inflammatory impacts on drug bioavailability through modulation of the brain, gastrointestinal tract and/or hepatic expression of metabolizing enzymes and transporters. Conclusion: Our hypothesis-generating approach identified a broad spectrum of PGx markers that interactively influence RIS exposure in ASD children, which indicated the need for further validation in population PK modeling studies to define polygenic scores for antipsychotic efficacy and safety, which could facilitate personalized therapeutic decision-making in this complex neurodevelopmental condition.