Combined chronic copper exposure and aging lead to neurotoxicity in vivo.

The environment, containing pollutants, toxins, and transition metals (copper, iron, manganese, and zinc), plays a critical role in neurodegenerative disease development. Copper occupational exposure increases Parkinson's disease (PD) risk. Previously, we determined the mechanisms by which copper induces dopaminergic cell death in vitro. The copper transporter protein 1 (Ctr1) overexpression led to intracellular glutathione depletion potentiating caspase-3 mediated cell death; oxidative stress was primarily cytosolic, and Nrf2 was upregulated mediating an antioxidant response; and protein ubiquitination, AMPK-Ulk1 signaling, p62, and Atg5-dependent autophagy were increased as a protective mechanism. However, the effect of chronic copper exposure on the neurodegenerative process has not been explored in vivo. We aimed to elucidate whether prolonged copper treatment reproduces PD features and mechanisms during aging. Throughout 40 weeks, C57BL/6J male mice were treated with copper at 0, 100, 250, and 500 ppm in the drinking water. Chronic copper exposure altered motor function and induced dopaminergic neuronal loss, astrocytosis, and microgliosis in a dose-dependent manner. α-Synuclein accumulation and aggregation were increased in response to copper, and the proteasome and autophagy alterations, previously observed in vitro, were confirmed in vivo, where protein ubiquitination, AMPK phosphorylation, and the autophagy marker LC3-II were also increased by copper exposure. Finally, nitrosative stress was induced by copper in a concentration-dependent fashion, as evidenced by increased protein nitration. To our knowledge, this is the first study combining chronic copper exposure and aging, which may represent an in vivo model of non-genetic PD and help to assess potential prophylactic and therapeutic approaches. DATA AVAILABILITY: The data underlying this article are available in the article.

Unscrambling the Role of Redox-Active Biometals in Dopaminergic Neuronal Death and Promising Metal Chelation-Based Therapy for Parkinson's Disease.

Biometals are all metal ions that are essential for all living organisms. About 40% of all enzymes with known structures require biometals to function correctly. The main target of damage by biometals is the central nervous system (CNS). Biometal dysregulation (metal deficiency or overload) is related to pathological processes. Chronic occupational and environmental exposure to biometals, including iron and copper, is related to an increased risk of developing Parkinson's disease (PD). Indeed, biometals have been shown to induce a dopaminergic neuronal loss in the substantia nigra. Although the etiology of PD is still unknown, oxidative stress dysregulation, mitochondrial dysfunction, and inhibition of both the ubiquitin-proteasome system (UPS) and autophagy are related to dopaminergic neuronal death. Herein, we addressed the involvement of redox-active biometals, iron, and copper, as oxidative stress and neuronal death inducers, as well as the current metal chelation-based therapy in PD.

Peripheral tissular analysis of rapamycin's effect as a neuroprotective agent in vivo.

Rapamycin is the best-characterized autophagy inducer, which is related to its antiaging and neuroprotective effects. Although rapamycin is an FDA-approved drug for human use in organ transplantation and cancer therapy, its administration as an antiaging and neuroprotective agent is still controversial because of its immunosuppressive and reported side effects. Therefore, it is critical to determine whether the dose that exerts a neuroprotective effect, 35 times lower than that used as an immunosuppressant agent, harms peripheral organs. We validated the rapamycin neuroprotective dosage in a Parkinson's disease (PD) model induced with paraquat. C57BL/6 J mice were treated with intraperitoneal (IP) rapamycin (1 mg/kg) three times per week, followed by paraquat (10 mg/kg) twice per week for 6 weeks, along with rapamycin on alternate days. Rapamycin significantly decreased dopaminergic neuronal loss induced by paraquat. Since rapamycin's neuroprotective effect in a PD model was observed at 7 weeks of treatment; we evaluated its effect on the liver, kidney, pancreas, and spleen. In addition, we prolonged treatment with rapamycin for 14 weeks. Tissue sections were subjected to histochemical, immunodetection, and morphometric analysis. Chronic rapamycin administration does not affect bodyweight, survival, and liver or kidney morphology. Although the pancreas tissular architecture and cellular distribution in Langerhans islets are modified, they may be reversible. The spleen B lymphocyte and macrophage populations were decreased. Notably, the lymphocyte T population was not affected. Therefore, chronic administration of a rapamycin neuroprotective dose does not produce significant tissular alterations. Our findings support the therapeutic potential of rapamycin as a neuroprotective agent.

Effect of methanolic extract of Mimosa malacophylla A.Gray in vero and HEK-293 cell lines, and in the morphology of kidney and bladder of rats with induced urolithiasis.

ETHNOPHARMACOLOGICAL RELEVANCE: Urolithiasis is the presence of stones in the kidney, ureters, bladder and/or urethra; it is the third most frequent disease of the urinary tract. Mimosa malacophylla A. Gray, is a species distributed in northern Mexico, where people traditionally use it for its diuretic effect, and to treat kidney diseases; however, no scientific reports have been found in relation to its antiurolithic properties. AIM OF THE STUDY: This study aimed to obtain a qualitative phytochemical profile of the methanolic extract (ME) of M. malacophylla, and to evaluate its potential cytotoxic effect in vitro and its antiurolithic activity in vivo. MATERIAL AND METHODS: Phytochemical screening was performed to demonstrate the presence of secondary metabolite groups in the methanolic extract of M. malacophylla. In vitro cytotoxicity assays (MTT and nucleotide labeling with DAPI) were performed to evaluate the effect of the extract on kidney cell lines. Urolithiasis was induced in the bladder of Wistar rats introducing zinc disks for the calculus formation and exposed to three concentrations of ME. RESULTS: Phytochemical screening showed phenols, steroids, terpenoids and carbohydrates. In vitro analysis demonstrated that concentrations below 300 µg/mL of ME did not produce a cytotoxic effect on renal Vero and HEK-293 cells. In vivo analysis of 15 days of exposition, revealed that the extract at concentrations of 50 mg/kg to 150 mg/kg were effective as an antiurolithic treatment, and did not produce morphological alterations in kidney or bladder in murine model of induced urolithiasis. CONCLUSIONS: The antiurolithic activity may be attributed to the presence of flavonoids, steroids and terpenes detected in the phytochemical screening which have been reported to possess this activity. These results could be useful to evaluate new alternatives and their potential therapeutic effect to treat renal or urinary affections.

Autophagy Stimulation Decreases Dopaminergic Neuronal Death Mediated by Oxidative Stress.

The neurodegenerative process of Parkinson's disease (PD) involves autophagy impairment and oxidative stress. Therefore, we wanted to determine whether stimulation of autophagy protects dopaminergic cell death induced by oxidative stress in a PD model. Since environmental exposure to herbicides increases the risk to develop PD, the experimental model was established using the herbicide paraquat, which induces autophagy disruption, oxidative stress, and cell death. Rapamycin-stimulated autophagy inhibited calpain-dependent and independent apoptosis induced by paraquat. Autophagy stimulation decreased oxidative stress and peroxiredoxins (PRXs) hyperoxidation induced by paraquat. Cells exposed to paraquat displayed abnormally large autophagosomes enclosing mitochondria, which correlates with an increase of p62, an essential mitophagy regulator. Interestingly, when autophagy was stimulated before paraquat treatment, autophagosome size and number were similar to that observed in control cells. Motor and cognitive function impairment induced by paraquat showed an improvement when preceded by autophagy stimulation. Importantly, dopaminergic neuronal death and microglial activation mediated by paraquat were significantly reduced by rapamycin-induced autophagy. Our results indicate that autophagy stimulation has a protective effect on dopaminergic neurons and may have a promising potential to prevent or delay PD progression.