Effects of chronic aspartame consumption on MPTP-induced Parkinsonism in male and female mice

Aspartame use and Parkinson's disease: review of associated effects on neurotransmitters, oxidative stress, and cognition

Objective: The purpose of this review was to assess the current evidence regarding the associated physiological and cognitive effects of aspartame (APM) consumption and Parkinson's Disease (PD).

METHODS

A total of 32 studies demonstrating effects of APM on monoamine deficiencies, oxidative stress, and cognitive changes were reviewed.

RESULTS

Multiple studies demonstrated decreased brain dopamine, decreased brain norepinephrine, increased oxidative stress, increased lipid peroxidation, and decreased memory function in rodents after APM use. In addition, PD animal models have been found to be more sensitive to the effects of APM.

DISCUSSION

Overall, studies of APM use over time yielded more consistent results; however, no study has examined long-term effects on APM in human PD patients. Based on the current evidence, long-term human based observational research is needed to further investigate the potential effect of APM on PD.

Updated systematic assessment of human, animal and mechanistic evidence demonstrates lack of human carcinogenicity with consumption of aspartame

Aspartame has been studied extensively and evaluated for its safety in foods and beverages yet concerns for its potential carcinogenicity have persisted, driven primarily by animal studies conducted at the Ramazzini Institute (RI). To address this controversy, an updated systematic review of available human, animal, and mechanistic data was conducted leveraging critical assessment tools to consider the quality and reliability of data. The evidence base includes 12 animal studies and >40 epidemiological studies reviewed by the World Health Organization which collectively demonstrate a lack of carcinogenic effect. Assessment of >1360 mechanistic endpoints, including many guideline-based genotoxicity studies, demonstrate a lack of activity associated with endpoints grouped to key characteristics of carcinogens. Other non-specific mechanistic data (e.g., mixed findings of oxidative stress across study models, tissues, and species) do not provide evidence of a biologically plausible carcinogenic pathway associated with aspartame. Taken together, available evidence supports that aspartame consumption is not carcinogenic in humans and that the inconsistent findings of the RI studies may be explained by flaws in study design and conduct (despite additional analyses to address study limitations), as acknowledged by authoritative bodies.

Protective Effects of Crocin Against Methotrexate-Induced Hepatotoxicity in Adult Male Albino Rats: Histological, Immunohistochemical, and Biochemical Study

BACKGROUND

Among the many known adverse effects of methotrexate (MTX), hepatotoxicity stands out as a major drawback that limits its therapeutic applicability. There is growing evidence that crocin has antioxidant, anti-hyperglycemic, cardioprotective, and anti-inflammatory effects. This study's aim is to evaluate the potential protective effect of crocin against MTX-induced liver damage in rats using biochemical, histological, and immunohistochemical analyses.

METHODS

Twenty-four adult male albino rats were split into four groups at random (six rats/group) as follows: normal control (saline, intraperitoneal (i.p.) injections), crocin-treated (100 mg/kg daily for 14 days, i.p.), MTX-treated (20 mg/kg single i.p. injection on day 15), and crocin/MTX-treated groups (crocin 100 mg/kg/day for 14 days, i.p. + MTX 20 mg/kg single i.p. injection on day 15). On day 16 of the experiment, blood and tissue specimens were used to assess the liver functions, oxidative stress markers, transforming growth factor beta 1 (TGF-β1), caspase-3, BCL-2-associated X protein (BAX), and B-cell lymphoma 2 (BCL-2) expression.

RESULTS

The results of the current research revealed the protective actions of crocin against MTX-induced hepatotoxicity. Our results showed that crocin possesses antioxidants (decrease malondialdehyde (MDA), increase glutathione (GSH) levels, and enhance catalase (CAT) and superoxide dismutase (SOD) enzymatic activity), anti-fibrotic (decrease TGF-β1), and anti-apoptotic (decrease BAX and caspase-3 expression while increase BCL-2) actions in liver. Moreover, crocin administration along with MTX restores the normal histological structure of hepatic tissues.

CONCLUSION

 The data presented in the current study using an in vivo animal model support the notion that crocin should be further studied in humans to assess its potential hepatoprotective effects against MTX-induced liver damage.

The effects of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) on the cognitive and motor functions in rodents: A systematic review and meta-analysis

Memory and motor deficits are commonly identified in Parkinson's disease (PD). 1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) is transformed to MPP+ via monoamine oxidase B (MAOB), which causes oxidative stress and destroys dopaminergic (DA) neurons in substantia nigra pars compacta (SNc) and is widely used to create animal models of PD. However, to-date, a comprehensive analysis of the MPTP effects on various aspects of PD does not exist. Here, we provide a systematic review and meta-analysis on the MPTP effects on memory and motor functions by analyzing 51 studies on more than one thousand animals mainly including rats and mice. The results showed that in addition to motor functions such as coordination, balance and locomotor activity, MPTP significantly affects various mnemonic processes including spatial memory, working memory, recognition memory, and associative memory compared with the control group with some differences between systemic and intra-nigral injections on spatial memory, familiar object recognition, and anxiety-like behaviors. Nevertheless, our analysis failed to find systematic relationship between MPTP injection protocol parameters reported and the extent of the induced PD symptoms that can be a cause of concern for replicability of MPTP studies.

Antioxidant and Anti-Inflammatory Effects of Crocin Ameliorate Doxorubicin-Induced Nephrotoxicity in Rats

Doxorubicin is a drug that belongs to the anthracycline antibiotics. Nephrotoxicity is one of the serious side effects of doxorubicin treatment. Crocin, which is one of the most bioactive components of saffron, has antioxidant, anti-inflammatory, and antitumor effects. The current study was aimed at investigating the possible protective effects of crocin against doxorubicin-induced nephrotoxicity to elucidate the underlying mechanism of this effect. The study included four groups, six rats in each group: normal control, crocin control, doxorubicin, and crocin/doxorubicin. Doxorubicin and crocin/doxorubicin groups received intraperitoneal injections of doxorubicin (3.5 mg/kg twice weekly for 3 weeks). Rats in the crocin control group and the crocin/doxorubicin group were treated with intraperitoneal injections of crocin (100 mg/kg body weight per day) for 3 weeks. Biomarkers of kidney function and oxidative stress as well as the abundance of mRNA for nuclear factor-κβ and inducible nitric oxide synthase were evaluated. In addition, the abundance of cyclooxygenase 2 and tumor necrosis factor α immunoreactivity was evaluated. Crocin treatment had renoprotective effects manifested by significant improvement in kidney function as well as a reduction in the abundance of biomarkers of oxidative stress markers and inflammatory mediators. In conclusion, crocin has a protective effect against doxorubicin-induced nephrotoxicity in rats by serving as an antioxidant and attenuating the expression of NF-κB, iNOS, COX2, and TNFα.

The food additive fast green FCF inhibits α-synuclein aggregation, disassembles mature fibrils and protects against amyloid-induced neurotoxicity

α-Synuclein (α-syn) aggregates into cytotoxic amyloid fibrils, which are recognized as the defining neuropathological feature of Parkinson's disease (PD). Therefore, inhibiting α-syn fibrillogenesis and disrupting the preformed fibrils are both considered attractive strategies to cure PD. We discovered that a safe food additive, fast green FCF, is capable of inhibiting α-synuclein fibrillogenesis and reducing the related cytotoxicity. Thioflavin T fluorescence assays demonstrated that fast green FCF could inhibit the fibrillogenesis α-synuclein. In the presence of 100 μM fast green FCF, amorphous aggregates were formed and observed by atomic force microscopy. Toxicity assays in cell cultures revealed that fast green FCF significantly reduced the cytotoxicity of α-syn. Molecular dynamics simulations revealed the potential mechanism of the interactions between fast green FCF and α-synuclein. Fast green FCF greatly disrupted the α-synuclein pentamer and reduced the β-sheet content by reducing both nonpolar and polar interactions. Furthermore, two binding sites were identified, named region I (Y39-K45) and region II (H50-Q62). Our data reveal that electrostatic interactions, hydrogen bonds, and π-π interactions synergistically contribute to the binding of fast green FCF to the α-synuclein pentamer. These results indicate that fast green FCF is a candidate prototype for the development of drugs against the aggregation of amyloid fibrils in PD.

Metabarcoding reveals that a non-nutritive sweetener and sucrose yield similar gut microbiota patterns in Wistar rats

The effects of non-nutritive sweeteners (NNS) on the gut microbiota are an area of increasing research interest due to their potential influence on weight gain, insulin resistance, and inflammation. Studies have shown that mice and rats fed saccharin develop weight gain and metabolic alterations, possibly related to changes in gut microbiota. Here, we hypothesized that chronic exposure to a commercial NNS would change the gut microbiota composition in Wistar rats when compared to sucrose exposure. To test this hypothesis, Wistar rats were fed either NNS- or sucrose-supplemented yogurt for 17 weeks alongside standard chow (ad libitum). The gut microbiome was assessed by 16S rDNA deep sequencing. Assembly and quantification were conducted using the Brazilian Microbiome Project pipeline for Ion Torrent data with modifications. Statistical analyses were performed in the R software environment. We found that chronic feeding of a commercial NNS-sweetened yogurt to Wistar rats, within the recommended dose range, did not significantly modify gut microbiota composition in comparison to sucrose-sweetened yogurt. Our findings do not support the hypothesis that moderate exposure to NNS is associated with changes in gut microbiota pattern compared to sucrose, at least in this experimental model.