β-Estradiol-3-benzoate confers neuroprotection in Parkinson MPP+ rat model through inhibition of lipid peroxidation

Investigating the TLR4/TAK1/IRF7 axis in NLRP3-Mediated Pyroptosis in Parkinson's Disease

In the realm of Parkinson's disease (PD) research, NLRP3 inflammasome-mediated pyroptosis has recently garnered significant attention as a potential novel form of dopaminergic neuronal death. Our previous research revealed the activation of innate immune-related genes, such as the TLR4 signaling pathway and interferon regulatory factor 7 (IRF7), although the specific mechanism remains unclear. Our current study shed light on whether the TLR4 signaling pathway and IRF7 can affect the pyroptosis of dopaminergic nerve cells and thus participate in the pathogenesis of PD. The PD model was constructed by MPP+ treatment of PC12 cells or stereotactic injection of the striatum of SD rats, and the expression of genes were detected by RT-qPCR and Western Blotting. Lentivirus, siRNA and (5Z)-7-Oxozeaenol were used to validate the regulation of this pathway on pyroptosis. The expression of TLR4, TAK1, IRF7 and pyroptosis molecular markers was upregulated after MPP+ treatment. IRF7 could affect dopaminergic neural cells pyroptosis by targeted regulation of NLRP3. Furthermore, inhibition of the TLR4/TAK1 signaling pathway led to a decrease in the expression of both IRF7 and NLRP3, while overexpression of IRF7 reversed the reduction in pyroptosis and increase in TH expression. TLR4/TAK1/IRF7 axis can promote PD by influencing pyroptosis through NLRP3.

Investigation of Antiparasitic Activity of Two Marine Natural Products, Estradiol Benzoate, and Octyl Gallate, on Toxoplasma gondii In Vitro

Toxoplasmosis, caused by Toxoplasma gondii, is a common disease worldwide and could be severe and even fatal in immunocompromised individuals and fetuses. Limitation in current available treatment options drives the need to develop novel therapeutics. This study assessed the anti-T. gondii potential of 103 marine natural products. A luminescence-based β-galactosidase activity assay was used to screen the marine natural products library. Afterward, those compounds that displayed over 70% parasite inhibition ratio were further chosen to assess their cytotoxicity. Compounds exhibiting low cytotoxicity (≥80% cell viability) were applied to evaluate the inhibition efficacy on discrete steps of the T. gondii lytic cycle, including invasion, intracellular growth, and egress abilities as well as the cell cycle. We found that both estradiol benzoate and octyl gallate caused >70% inhibition of tachyzoite growth with IC₅₀ values of 4.41 ± 0.94 and 5.66 ± 0.35 μM, respectively, and displayed low cytotoxicity with TD₅₀ values of 34.11 ± 2.86 and 26.4 ± 0.98 μM, respectively. Despite their defects in inhibition of invasion and egress of tachyzoite, the two compounds markedly inhibited the tachyzoite intracellular replication. Flow cytometric analyses further suggested that the anti-T. gondii activity of estradiol benzoate, rather than octyl gallate, may be linked to halting cell cycle progression of tachyzoite from G1 to S phase. Taken together, these findings suggest that both estradiol benzoate and octyl gallate are potential inhibitors for anti-T. gondii infection and support the further exploration of marine natural products as a thinkable source of alternative and active agents against T. gondii.

Expression of PON2 isoforms varies among brain regions in male and female African green monkeys

Mitochondrial dysfunction and oxidative stress contribute to the neuropathology of neurodegenerative disorders such as Parkinson's disease (PD). Paraoxonase-2 (PON2) is a mitochondrial protein that mitigates oxidative stress, enhances mitochondrial function and exhibits anti-inflammatory properties. Previously, we have documented sex-based variation in PON2 with higher brain PON2 expression in female (2-fold) as compared to male African green monkeys. This aim of this study is to identify PON2 isoforms and explore the region-based variations in the protein level of PON2 in brain of African green monkeys. Male and female brain tissue samples (striatum, hippocampus, occipital cortex, dorsolateral prefrontal cortex) from African green monkeys (Chlorocebus sabaeus) were analyzed by western blotting technique for PON2 expression. We found two PON2 isoforms (39 and 41 kDa) in each examined brain region of male and female monkeys. Male monkeys showed no significant difference in the expression level of PON2 isoforms among different brain regions whereas female monkeys showed a significant difference in the expression level of PON2 isoforms in all examined regions except dorsolateral prefrontal cortex. In addition, the result revealed highest expression of PON2 protein in striatum compared to other brain regions in both male and female monkeys. This report is the first to quantify expression of PON2 isoforms in different brain regions and it also establishes the existence of sex as well as region-based variation in PON2 protein expression in primate brain. Since PON2 serves a protective role for dopaminergic neurons it should be considered as a druggable target for oxidative stress-related neurodegenerative disorders like PD. We anticipate that the outcome of this study will contribute to the development of neuroprotective strategies in PD.

Antioxidant Effect of Hydroxytyrosol, Hydroxytyrosol Acetate and Nitrohydroxytyrosol in a Rat MPP+ Model of Parkinson's Disease

3,4-Dihydroxyphenyl ethanol, known as hydroxytyrosol (HTy), is a phenylpropanoid found in diverse vegetable species. Several studies have demonstrated that HTy is a potent antioxidant. Thus, our study is aimed to evaluate the antioxidant effect of HTy and its derivatives, hydroxytyrosol acetate (HTyA) and nitrohydroxytyrosol (HTyN), in a model of oxidative stress induced by 1-methyl-4-phenylpyridinium (MPP⁺) in rats. Rats were administered intravenously (i.v.) in the tail with 1 mL saline solution or polyphenol compound (1.5 mg/kg) 5 min before intrastriatal infusion of 10 µg MPP⁺/8 µL. We found that rats injured with MPP⁺, pretreatment with HTy, HTyA or HTyN significantly decreased ipsilateral turns. This result was consistent with a significant preservation of striatal dopamine levels and decreased lipid fluorescence products (LFP), a marker of oxidative stress. Brain GSH/GSSG ratio, from rats pretreated with HTy or HTyN showed a significant preservation of that marker, decreased as a consequence of MPP⁺-induced oxidative damage. These results show an antioxidant effect of HTy, HTyA and HTyN in the MPP⁺ model of Parkinson's disease in the rat.

Delay in puberty indices of Wistar rats caused by Cadmium. Focus on the redox system in reproductive organs

Puberty is a transitional period from juvenile stage to adulthood, followed by the functional maturation of gonads and reproductive organs. This period is sensitive to environmental pollutants like cadmium (Cd), a heavy metal that represents a serious health risk. Cd is an endocrine disruptor that interferes with reproduction by causing oxidative stress in the reproductive organs, affecting the sexual function and decreasing testosterone (T) levels. However, little research has been done on the effects of Cd on puberty markers and antioxidant systems. In this study, we evaluated the effects of Cd on puberty markers: preputial separation, testes descent and T levels, and the antioxidant activity (SOD, CAT, GSH/GSSG and TAC) in the seminal vesicles, testis and epididymis. Male Wistar pups were treated with 1 mg/kg Cd or saline solution by i.p. injection from day 1 to 35; the other treatment was administrated for 49 days. At the end of treatment, the animals were sacrificed, and the tissues of interest dissected, weighed and prepared for the respective assays. Cd treated rats from birth to puberty showed a delay onset in the puberty markers and a low weight in reproductive organs. Also, Cd induced differential effects on the redox system in reproductive organs and decreased T levels, these effects played a pivotal role in the delay of puberty markers onset (testes descent and preputial separation), affecting the development and sexual maturity of the male rats.

Pretreatment with Human Lactoferrin Had a Positive Effect on the Dynamics of Mouse Nigrostriatal System Recovery after Acute MPTP Exposure

We studied the effect of human lactoferrin (hLf) on degenerative changes in the nigrostriatal system and associated behavioral deficits in the animal model of Parkinson disease. Nigrostriatal dopaminergic injury was induced by single administration of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP; 40 mg/kg) to five-month-old C57Bl/6 mice. Behavioral disturbances were assessed in the open field and rotarod tests and by the stride length analysis. Structural deficits were assessed by the counts of tyrosine hydroxylase (TH)-immunoreactive neurons in the substantia nigra and optical density (OD) of TH-immunolabeled fibers in the striatum. Acute MPTP treatment induced long-term behavioral deficit and degenerative changes in the nigrostriatal system. Pretreatment with hLf prevented body weight loss and promoted recovery of motor functions and exploratory behavior. Importantly, OD of TH-positive fibers in the striatum of mice treated with hLf almost returned to normal, and the number of TH-positive cells in the substantia nigra significantly increased on day 28. These results indicate that hLf produces a neuroprotective effect and probably stimulates neuroregeneration under conditions of MPTP toxicity in our model. A relationship between behavioral deficits and nigrostriatal system disturbances at delayed terms after MPTP administration was found.

Behavioral Tests in Neurotoxin-Induced Animal Models of Parkinson's Disease

Currently, neurodegenerative diseases are a major cause of disability around the world. Parkinson's disease (PD) is the second-leading cause of neurodegenerative disorder after Alzheimer's disease. In PD, continuous loss of dopaminergic neurons in the substantia nigra causes dopamine depletion in the striatum, promotes the primary motor symptoms of resting tremor, bradykinesia, muscle rigidity, and postural instability. The risk factors of PD comprise environmental toxins, drugs, pesticides, brain microtrauma, focal cerebrovascular injury, aging, and hereditary defects. The pathologic features of PD include impaired protein homeostasis, mitochondrial dysfunction, nitric oxide, and neuroinflammation, but the interaction of these factors contributing to PD is not fully understood. In neurotoxin-induced PD models, neurotoxins, for instance, 6-hydroxydopamine (6-OHDA), 1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP), 1-Methyl-4-phenylpyridinium (MPP+), paraquat, rotenone, and permethrin mainly impair the mitochondrial respiratory chain, activate microglia, and generate reactive oxygen species to induce autooxidation and dopaminergic neuronal apoptosis. Since no current treatment can cure PD, using a suitable PD animal model to evaluate PD motor symptoms' treatment efficacy and identify therapeutic targets and drugs are still needed. Hence, the present review focuses on the latest scientific developments in different neurotoxin-induced PD animal models with their mechanisms of pathogenesis and evaluation methods of PD motor symptoms.

Protection induced by estradiol benzoate in the MPP+ rat model of Parkinson's disease is associated with the regulation of the inflammatory cytokine profile in the nigro striatum

Previously, we have demonstrated that β-estradiol-3-benzoate (EB) has a protective effect on the neurodegenerative experimental model of Parkinson's disease. The protective effect is through the induction of the expression of paraoxonase-2 (PON2) in the striatum. PON2 has proven to have antioxidant and anti-inflammatory activity, this protein has a beneficial effect in MPP⁺ model in rats decreasing the lipid peroxidation and the oxidative stress. Furthermore, the molecular effect and the pathway by which EB induces protection were not further pursued. This study shows the regulation by EB of the anti-inflammatory effect through the modulation of cytokines, antioxidant enzymes and PON2 in the rat striatum. Rats were gonadectomized and 30 days after were randomly assigned into four experimental groups; only vehicles (Control group); EB treatment (EB group); MPP⁺ injury (M group); EB plus MPP⁺ injured (EB/M group). EB treatment consisted of 100 μg of the drug administered every 48 h for 11 days. Results showed that EB (group EB/M) treatment decrease significantly (40%) the number of ipsilateral turns respect to the M group and prevents significantly the dopamine (DA) decreased induced by MPP⁺ (~75%). This results are correlate with a significant decrease in the level of lipid peroxidation (60%) of the EB/M group respect to the M group. The EB treatment showed protection against neurotoxicity induced with MPP⁺, this could be due to EB capacity to prevent the increase in the expression level of proinflammatory cytokines TNF-α, IL-1 and IL-6 induced by MPP⁺. While, TGF-β1 and TGF-β3 expression was reduced in the rats treated only with MPP⁺, in the rats of EB/M group the expression of both cytokines was increased. EB protective effect against MPP⁺ neurotoxicity is related to antioxidant effect of PON2, pro-inflammatory cytokines and GSHR but not to SOD2, catalase, GPX1 or GPX4.

Tianma Gouteng granules decreases the susceptibility of Parkinson's disease by inhibiting ALOX15-mediated lipid peroxidation

ETHNOPHARMACOLOGICAL RELEVANCE

Tianma Gouteng granules (TG), a clinical prescription of traditional Chinese medicine, has been clinically applied to treat Parkinson's disease (PD) in combination with Madopar, as included in the Chinese Pharmacopoeia (2015). TG has the potential to decrease the susceptibility of PD pharmacologically, however the mechanisms need detailed demonstration.

AIM OF THE STUDY

To evaluate the pharmacological activities, as well as the possible mechanism of TG in diverse models of PD.

MATERIALS AND METHODS

6-OHDA-treated rats, MPTP-treated mice, and α-synuclein A53T overexpressed mice, were utilized as PD animal models. Rotarod, locomotor activity, inclined plane and traction tests were used for behavioral assessment. Immunohistochemistry was used for tyrosine hydrolase determination. Western blot were conducted for detection of 4-HNE and 15-lipoxygenase-1 (ALOX15). The interactions of ALOX15 with the components in TG were predicted by molecular docking approach.

RESULTS

Lipid peroxidation was involved in dopaminergic neuron damage in 6-OHDA-induced rat models. In MPTP-treated mice, the inhibition of lipid peroxidation improved behavioral and pathological symptoms of PD. The lipid peroxidation-related protein, ALOX15 was found to be the key factor in PD process in diverse PD models including 6-OHDA-treated rats, MPTP-treated mice, and α-synuclein A53T overexpressed mice. TG treatment significantly relieved behavioral and pathological symptoms of MPTP-induced PD mouse models with a potential mechanism of alleviating ALOX15-induced lipid peroxidation. Moreover, the results of molecular docking analysis show that compounds in TG might have interactions with ALOX15.

CONCLUSIONS

TG effectively improved the behavioral and dopaminergic neuron damage in diverse PD models. The mechanism of this action may be related to the direct inhibition of ALOX15 and the relief of lipid peroxidation.

Molecular mechanisms and cellular events involved in the neuroprotective actions of estradiol. Analysis of sex differences

Estradiol, either from peripheral or central origin, activates multiple molecular neuroprotective and neuroreparative responses that, being mediated by estrogen receptors or by estrogen receptor independent mechanisms, are initiated at the membrane, the cytoplasm or the cell nucleus of neural cells. Estrogen-dependent signaling regulates a variety of cellular events, such as intracellular Ca²⁺ levels, mitochondrial respiratory capacity, ATP production, mitochondrial membrane potential, autophagy and apoptosis. In turn, these molecular and cellular actions of estradiol are integrated by neurons and non-neuronal cells to generate different tissue protective responses, decreasing blood-brain barrier permeability, oxidative stress, neuroinflammation and excitotoxicity and promoting synaptic plasticity, axonal growth, neurogenesis, remyelination and neuroregeneration. Recent findings indicate that the neuroprotective and neuroreparative actions of estradiol are different in males and females and further research is necessary to fully elucidate the causes for this sex difference.

Bioenergetics and Autophagic Imbalance in Patients-Derived Cell Models of Parkinson Disease Supports Systemic Dysfunction in Neurodegeneration

Parkinson's disease (PD) is the second most prevalent neurodegenerative disorder worldwide affecting 2-3% of the population over 65 years. This prevalence is expected to rise as life expectancy increases and diagnostic and therapeutic protocols improve. PD encompasses a multitude of clinical, genetic, and molecular forms of the disease. Even though the mechanistic of the events leading to neurodegeneration remain largely unknown, some molecular hallmarks have been repeatedly reported in most patients and models of the disease. Neuroinflammation, protein misfolding, disrupted endoplasmic reticulum-mitochondria crosstalk, mitochondrial dysfunction and consequent bioenergetic failure, oxidative stress and autophagy deregulation, are amongst the most commonly described. Supporting these findings, numerous familial forms of PD are caused by mutations in genes that are crucial for mitochondrial and autophagy proper functioning. For instance, late and early onset PD associated to mutations in Leucine-rich repeat kinase 2 (LRRK2) and Parkin (PRKN) genes, responsible for the most frequent dominant and recessive inherited forms of PD, respectively, have emerged as promising examples of disease due to their established role in commanding bioenergetic and autophagic balance. Concomitantly, the development of animal and cell models to investigate the etiology of the disease, potential biomarkers and therapeutic approaches are being explored. One of the emerging approaches in this context is the use of patient's derived cells models, such as skin-derived fibroblasts that preserve the genetic background and some environmental cues of the patients. An increasing number of reports in these PD cell models postulate that deficient mitochondrial function and impaired autophagic flux may be determinant in PD accelerated nigral cell death in terms of limitation of cell energy supply and accumulation of obsolete and/or unfolded proteins or dysfunctional organelles. The reliance of neurons on mitochondrial oxidative metabolism and their post-mitotic nature, may explain their increased vulnerability to undergo degeneration upon mitochondrial challenges or autophagic insults. In this scenario, proper mitochondrial function and turnover through mitophagy, are gaining in strength as protective targets to prevent neurodegeneration, together with the use of patient-derived fibroblasts to further explore these events. These findings point out the presence of molecular damage beyond the central nervous system (CNS) and proffer patient-derived cell platforms to the clinical and scientific community, which enable the study of disease etiopathogenesis and therapeutic approaches focused on modifying the natural history of PD through, among others, the enhancement of mitochondrial function and autophagy.

Aberrant Cerebral Activity in Early Postmenopausal Women: A Resting-State Functional Magnetic Resonance Imaging Study

Background: Early postmenopausal women frequently suffer from cognitive impairments and emotional disorders, such as lack of attention, poor memory, deficits in executive function and depression. However, the underlying mechanisms of these impairments remain unclear. Method: Forty-three early postmenopausal women and forty-four age-matched premenopausal controls underwent serum sex hormone analysis, neuropsychological testing and resting-state functional magnetic resonance imaging (rs-fMRI). Degree centrality (DC) analysis was performed to confirm the peak points of the functionally abnormal brain areas as the centers of the seeds. Subsequently, the functional connectivity (FC) between these abnormal seeds and other voxels across the whole brain was calculated. Finally, the sex hormone levels, neuroimaging indices and neuropsychological data were combined to detect potential correlations. Results: Compared with the premenopausal controls, the early postmenopausal women exhibited significantly higher serum follicle-stimulating hormone (FSH) levels, more severe climacteric and depressive symptoms, worse sleep quality and more extensive cognitive impairments. Concurrently, the neuroimaging results showed elevated DC values in the left amygdala (AMYG.L), reduced DC values in the left middle occipital gyrus (MOG.L) and right middle occipital gyrus (MOG.R). When we used the AMYG.L as the seed point, FC with the left insula (INS.L), bilateral prefrontal cortex (PFC) and right superior frontal gyrus (SFG.R) was increased; these regions are related to depressive states, poor sleep quality and decreased executive function. When bilateral MOG were used as the seed points, FC with left inferior parietal gyrus (IPG.L), this area closely associated with impaired memory, was decreased. Conclusion: These results illuminated the regional and network-level brain dysfunction in early postmenopausal women, which might provide information on the underlying mechanisms of the different cognitive impairments and emotional alterations observed in this group.

Chronic Consumption of Fructose Induces Behavioral Alterations by Increasing Orexin and Dopamine Levels in the Rat Brain

It has been widely described that chronic intake of fructose causes metabolic alterations which can be associated with brain function impairment. In this study, we evaluated the effects of fructose intake on the sleep–wake cycle, locomotion, and neurochemical parameters in Wistar rats. The experimental group was fed with 10% fructose in drinking water for five weeks. After treatment, metabolic indicators were quantified in blood. Electroencephalographic recordings were used to evaluate the sleep architecture and the spectral power of frequency bands. Likewise, the locomotor activity and the concentrations of orexin A and monoamines were estimated. Our results show that fructose diet significantly increased the blood levels of glucose, cholesterol, and triglycerides. Fructose modified the sleep–wake cycle of rats, increasing the waking duration and conversely decreasing the non-rapid eye movement sleep. Furthermore, these effects were accompanied by increases of the spectral power at different frequency bands. Chronic consumption of fructose caused a slight increase in the locomotor activity as well as an increase of orexin A and dopamine levels in the hypothalamus and brainstem. Specifically, immunoreactivity for orexin A was increased in the ventral tegmental area after the intake of fructose. Our study suggests that fructose induces metabolic changes and stimulates the activity of orexinergic and dopaminergic neurons, which may be responsible for alterations of the sleep–wake cycle.