Methyl aspartylphenylalanine, the pons and cerebellum in mice: An evaluation of motor, morphological, biochemical, immunohistochemical and apoptotic effects

Daytime aspartame intake results in larger influences on body weight, serum corticosterone level, serum/cerebral cytokines levels and depressive-like behaviors in mice than nighttime intake

Aspartame (APM) is one of the most widely used artificial sweeteners worldwide. Studies have revealed that consuming APM may negatively affect the body, causing oxidative stress damage to multiple organs and leading to various neurophysiological symptoms. However, it's still unclear if consuming APM and one's daily biological rhythm have an interactive effect on health. In this study, healthy adult C57BL/6 mice were randomly divided into four groups: Control group (CON), oral gavage sham group (OGS), daytime APM intragastric group (DAI) and nighttime APM intragastric group (NAI). DAI and NAI groups were given 80 mg/kg body weight daily for 4 weeks. We found that DAI and NAI groups had significantly increased mean body weight, higher serum corticosterone levels, up-regulated pro-inflammatory responses in serum and brain, and exacerbated depressive-like behaviors than the CON and the two APM intake groups. Moreover, all these changes induced by APM intake were more significant in the DAI group than in the NAI group. The present study, for the first time, revealed that the intake of APM and daily biological rhythm have an interactive effect on health. This suggests that more attention should be paid to the timing of APM intake in human beings, and this study also provides an intriguing clue to the circadian rhythms of experimental animals that researchers should consider more when conducting animal experiments.

Relationship between Aspartame-Induced Cerebral Cortex Injury and Oxidative Stress, Inflammation, Mitochondrial Dysfunction, and Apoptosis in Sprague Dawley Rats

There are emerging concerns about the potential cerebral cortex injury from aspartame due to the accumulation of the various neurotoxic metabolic components in the central nervous system after long-term dietary exposure. The aim of this study was to evaluate the effect of oral aspartame consumption on cerebral cortex injury in the rat brain, and further evaluate the various underlying molecular mechanisms, with a special focus on oxidative stress, inflammation, mitochondrial dysfunction, and apoptosis pathways. Sprague Dawley rats (nineteen, female) were randomly sub-divided into three groups: (i) normal diet with vehicle: control group (five rats), (ii) low dose of aspartame group (LA): seven rats received 30 mg/kg body weight (bw) daily doses of aspartame, (iii) high dose of aspartame group (HA): seven rats received 60 mg/kg bw daily doses of aspartame. After 8 weeks, the LA and HA groups showed lower expression levels of brain-derived neurotrophic factor (BDNF), antioxidant enzyme activity (SOD2, CAT), antioxidant marker (Nrf2), inflammatory response (IκB), mitochondrial biogenesis (Sirt1, PGC1α, Nrf1, TFAM), mitochondrial DNA (mtDNA) copy number, and apoptosis-related proteins (Bax, Caspase-3) expressions. Aspartame administration also elevated oxidative stress levels (Malondialdehyde, MDA), 8-hydroxy-2-deoxy guanosine (8-OHdG), PGE2 and COX-2 expressions, pro-inflammatory cytokines (TNFα, IL6, IL1β), antioxidant marker expression (Keap1), inflammatory responses (iNOS, NFκB), and glial fibrillary acidic protein (GFAP) levels in the cerebral cortex of the rats, thereby contributing to the reduced survival of pyramidal cells and astrocyte glial cells of the cerebral cortex. Therefore, these findings imply that aspartame-induced neurotoxicity in rats' cerebral cortex could be regulated through four mechanisms: inflammation, enhanced oxidant stress, decreased mitochondrial biogenesis, and apoptosis pathways.

Biflavonoid quercetin protects against cyclophosphamide-induced organ toxicities via modulation of inflammatory cytokines, brain neurotransmitters, and astrocyte immunoreactivity

BACKGROUND

Cyclophosphamide use has been associated with increased oxidative stress in cells and tissues. Quercetin's antioxidative properties make it of potential benefit in such conditions of oxidative stress.

OBJECTIVE

To assess quercetin's ability to mitigate cyclophosphamide-induced organ toxicities in rats.

METHODS

Sixty rats were assigned into six groups. Groups A and D served as normal and cyclophosphamide control and were fed standard rat chow, groups B and E were fed quercetin supplemented diet (100 mg/kg of feed), while those in groups C and F were fed quercetin at 200 mg/kg of feed. Groups A-C received intraperitoneal (ip) normal saline on days 1 and 2, while D-F received ip cyclophosphamide (150 mg/kg/day on days 1 and 2). On day 21, behavioural tests were carried out, animals were sacrificed and blood samples taken. Organs were processed for histological study.

RESULTS

Quercetin reversed cyclophosphamide-induced decrease in body weight, food intake and total antioxidant capacity, and increase in lipid peroxidation (p = 0.001), It also reversed derangement in levels of liver transaminase, urea, creatinine and proinflammatory cytokines (p = 0.001). Improvement in working-memory and anxiety-related behaviours were also observed. Finally, quercetin reversed alterations in levels of acetylcholine, dopamine and brain-derived neurotropic factor (p = 0.021); while reducing serotonin levels and astrocyte immunoreactivity.

CONCLUSION

Quercetin shows significant ability to protect against cyclophosphamide-induced changes in rats.

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.

Food-added azodicarbonamide alters haematogical parameters, antioxidant status and biochemical/histomorphological indices of liver and kidney injury in rats

OBJECTIVES

Azodicarbonamide (ADA) is a dough enhancer currently used as a replacement for potassium bromate in the process of bread-making in countries such as Nigeria. However, comprehensive information on the toxicological profile of ADA is not readily available. The present study investigated the toxicological effects of ADA in rats.

METHODS

Twenty-four adult rats were randomly assigned into four groups of six rats each. Animals in group A served as the control (administered standard diet), whereas animals in groups B, C and D were fed ADA in food at 1, 2 and 4%, respectively. Standard or ADA diet was fed to the animals daily for a period of 28 days. Body weight was measured weekly, whereas food and water consumption was measured daily. On day 28, animals were fasted overnight after which they were euthanised. Blood samples taken were used for assessment of fasting blood glucose, haematological parameters, serum lipids, antioxidant status, lipid peroxidation status, electrolytes and urea, plasma proteins and biochemical parameters of liver and kidney injury. The liver and kidneys were then excised and processed for general histological study.

RESULTS

The results showed that repeated administration of ADA was associated with dose-related decrease in weight gain, decrease in overall food consumption, decreased superoxide dismutase activity/glutathione level and increased lipid peroxidation. There was also biochemical and morphological evidence of liver and kidney injury.

CONCLUSIONS

These findings suggest that food-added ADA could be injurious to the body cells and organs in rats.

Mesenchymal stem cells versus curcumin in enhancing the alterations in the cerebellar cortex of streptozocin-induced diabetic albino rats. The role of GFAP, PLC and α-synuclein

BACKGROUND

Diabetes mellitus is the disease, termed either by insulin paucity or resistance and hyperglycemia. The selection of the cerebellum was built on its specific functions. The aim of this study was to investigate a comparison between the possible therapeutic effects of MSCs and curcumin against fluctuations in the cerebellar cortex of STZ-induced diabetic albino rats.

MATERIALS AND METHODS

Forty rats were divided into five groups: control, sham control, streptozotocin-induced diabetes, diabetes and MSCs administered and diabetes and curcumin administered. Light microscopic (H&E), immune-histochemical; Glial fibrillary acidic protein (GFAP), real-time PCR; phospholipase-C (PLC) and α-synuclein, histomorphometric analysis, oxidative / anti-oxidatants; malondialdehyde (MDA)/ superoxide dismutase (SOD) glutathione (GSH) and were made.

RESULTS

The histopathological examination of the STZ-induced diabetic rats revealed alterations in the molecular, purkinje and granular layers. Abnormal organizations, vacuolation, patchy loss of purkinje cells were detected. Some purkinje cells migrated into the granular layer.Hemorrhage in pia mater outspreading to cerebellar layers is discerned. Purkinje cells showed karyorrhexis. The mean value of area percentage for GFAP immune- reactivity revealed 360 % significant increase compared to that of the control group. Also, MDA level was significantly increased while the SOD and GSH levels were significantly lower when compared to the control group. Meanwhile, mean values of PLC demonstrated significant decrease, while α-synuclein levels displayed a significant increment in the diabetic group. Administration of curcumin and MSCs extremely ameliorated the previous alterations.

CONCLUSION

the deleterious alterations on the cerebellar cortex induced by diabetes were obviously improved when treated with either MSCs or curcumin.

An Assessment of the Effects of Azodicarbonamide-containing Diet on Neurobehaviour, Brain Antioxidant Status and Membrane Lipid Peroxidation Status in Rats

BACKGROUND

Azodicarbonamide is a dough-enhancer used in the process of breadmaking in countries like Nigeria. While there have been suggestions that it is a sensitizer of the respiratory system, there is a dearth of information on its effects on the central nervous system.

AIM

This study assessed the effects of azodicarbonamide on the central nervous system (ADA) in rats.

OBJECTIVE

The effects of ADA-containing diet on neurobehaviour, brain antioxidant status, and neuromorphology of selected brain regions in rats were examined.

METHODS

Forty adult rats were randomly-assigned into four groups of ten rats each, and were given standard diet or diet containing ADA at 1, 2 and 4% respectively. Rats were fed a standard diet or ADA-containing diet for a period of 28 days. Weekly body weight assessment and daily estimation of food intake were done. Behavioural tests {in the Open field, Y-maze, radial-arm maze, and Elevated Plus Maze (EPM)} were conducted on day 29. Twenty-four hours after the last behavioural test, animals were euthanised, whole brains were dissected, weighed, and either homogenised for assessment of lipid peroxidation and antioxidant status; or sectioned and processed for general histology.

RESULTS

Consumption of ADA-containing diet was associated with a significant decrease in weight gain/food intake, and significant suppression of horizontal locomotion and rearing behaviours; however, grooming activity increased significantly. Also, there was a significant reduction of open-arm time in the EPM and a significant increase in Y-maze alternation (at the lowest concentration of ADA). ADA-containing diet was not associated with significant changes in brain oxidative status or neuromorphology.

CONCLUSION

The study showed that while ADA-containing diet may alter neurobehaviour in rats; this was not associated with evidence of brain oxidative stress or neuro-histomorphological alterations.

High Dietary Fat Modulates Neurobehavioural Effect of Lopinavir/ Ritonavir in Mice

BACKGROUND

Lopinavir/Ritonavir (LR) is a protease inhibitor used human immunodeficiency virus infection management. There have been issues regarding the effects of fat on LR efficacy and the possibility of neurological deficits following prolonged use, there is however a dearth of research examining this.

AIMS

The effects of LR administered with normal or High-Fat Diet (HFD) on neurobehaviour, neurochemistry and oxidative stress in healthy mice were examined.

METHODS

Mice were randomly-assigned into eight groups of ten (n=10) animals each. The groups were normal control [Standard Diet, (SD)], HFD control, 3 groups of LR incorporated into SD (100/25, 200/50 and 400/100 mg/kg of feed), and 3 groups of LR with HFD (100/25, 200/50 and 400/100 mg/kg of feed). Mice were fed daily for six weeks, following which open field, elevated-plus maze (EPM), radial-arm maze and Y-maze behaviours were scored. Twenty-four hours after tests, mice were euthanised and brains were homogenised for estimation of oxidative stress, L-glutamate level and acetylcholinesterase activity.

RESULTS

LR was associated with a reduction in HFD-induced weight gain, suppression of open-field behaviours with SD, and counteraction of HFD-induced changes in working-memory, open-field and anxiety-related behaviours. Also, LR causes increased lipid peroxidation and superoxide dismutase activity; and a decrease in brain glutamate, irrespective of dietary composition. Increased fat catabolism leading to increased oxidative stress could possibly account for the weight changes, while a decrease in brain glutamate could account for the changes in open-field behaviours in mice fed SD.

CONCLUSION

LR alters neurobehaviour, oxidative stress and brain glutamate in mice; however, only its effects on neurobehaviour are affected by diet.

Subchronic ketamine alters behaviour, metabolic indices and brain morphology in adolescent rats: Involvement of oxidative stress, glutamate toxicity and caspase-3-mediated apoptosis

Ketamine is a dissociative anaesthetic agent whose recreational use amongst adolescents and young adults is reaching epidemic proportions in a number of countries. While animal studies have examined the long-term detrimental effects of early-life ketamine exposure, there is a paucity of information on the immediate effects of ketamine following subchronic administration in the adolescence period. Adolescent rats were assigned into four groups of 10 animals each, administered intraperitoneal (i.p) injections of vehicle or one of three doses of ketamine (7.5, 15 or 30 mg/kg daily) for 8 weeks, and then exposed to behavioural paradigms. Rats were then euthanised after an overnight fast, and blood taken was used for measurement of metabolic indices. The brains were dissected out and either homogenised for estimation of neurochemical parameters, or processed for histological and immunohistochemical studies. Results showed that subchronic administration of ketamine was associated with a lesser weight gain inspite of an increase in food intake across the treatment groups. There was a dose-dependent increase in open-field novelty-induced behaviours, a decline in spatial working-memory, and an anxiolytic effect in the elevated-plus maze. There was associated derangement of serum triglyceride, and increase in brain glutamate levels, acetylcholinesterase activity, plasma/brain oxidative stress parameters, caspase-3 activity and biochemical indices of hepatic and renal function. Ketamine administration was also associated with neurodegenerative changes in the cerebral cortex, hippocampus, cerebellum and the pons. In conclusion, subchronic administration of ketamine to adolescent rats was associated with dose-related memory loss, oxidative stress and possibly caspase-3 mediated neurodegenerative changes.