Perfusion alters free zinc levels in the rodent brain

The Zinc Ionophore Clioquinol Reduces Parkinson's Disease Patient-Derived Brain Extracts-Induced Neurodegeneration

Parkinson's disease (PD) is pathologically characterized by intracellular α-synuclein-rich protein aggregates, named Lewy bodies (LB), and by the progressive loss of dopaminergic neurons in the substantia nigra. Several heavy metals, including zinc (Zn), have been suggested to play a role in PD progression, although the exact role of Zn in neurodegeneration remains to be fully elucidated. To address this gap, we investigated the effects of Zn modulation on the progression of degeneration in mice injected with PD patient-derived LB-extracts carrying toxic α-synuclein aggregates. Zn modulation was achieved using either a clioquinol-enriched diet, a Zn ionophore that redistributes cellular Zn, or a Zn-enriched diet that increases Zn levels. Clioquinol treatment significantly prevented dopaminergic neurodegeneration and reduced α-synuclein-associated pathology in LB-injected mice, while no differences were observed with Zn supplementation. Biochemical analyses further demonstrate that the expression levels of vesicle-specific Zn transporter ZnT3 in the striatum of LB-injected mice treated with clioquinol were decreased, suggesting an intracellular redistribution of Zn. Additionally, we found that clioquinol modulates the autophagy-lysosomal pathway by enhancing lysosomal redistribution within the neuronal compartments. Collectively, we found that in vivo pharmacological chelation of Zn, by dampening Zn-mediated cytotoxicity, can result in an overall attenuation of PD-linked lysosomal alterations and dopaminergic neurodegeneration. The results support zinc chelation as a disease-modifying strategy for treating PD.

Incorporation of docosahexaenoic acid (DHA) enhances nanodelivery of antiretroviral across the blood-brain barrier for treatment of HIV reservoir in brain

Although the newer antiretroviral (ARV) drugs are highly active against the human immunodeficiency virus (HIV) in the body compartment, they often fail to effectively tackle the HIV reservoir in the brain because of inefficient penetration to the blood-brain barrier (BBB). In this study, we investigated the potential benefits of incorporating docosahexaenoic acid (DHA), an omega-3 fatty acid essential for brain development, in lipid nanocarriers for facilitating the BBB passage of an ARV darunavir. The resulting nanocarriers (nanoARVs) containing 5-15% DHA were 90-140 nm in size, had high darunavir payload (~11-13% w/w), good stability and minimal cellular toxicity, and could be further decorated with transferrin (Tf) for Tf-receptor targeting. In BBB models of hCMEC/d3 cells, nanoARVs with higher DHA content achieved increased nanocarrier uptake and up to 8.99-fold higher darunavir permeation than free darunavir. In animals, nanoARVs were able to achieve 3.38-5.93-fold increase in brain darunavir level over free darunavir. Tf-conjugated nanoARVs also achieved significantly higher anti-HIV activity than free darunavir (viral titer 2 to 2.6-fold higher in latter group). Comparison of DHA incorporation and Tf-receptor targeting showed that while both strategies could enhance the cellular uptake and brain accumulation of the nanocarriers, DHA was more effective (P < 0.05) for improving BBB permeation and brain accumulation of the darunavir payload. Substituting DHA with another oil noticeably reduced the cellular uptake of nanoARVs. Overall, this proof-of-concept study has supported the development of DHA-based nanoARVs as an effective, safe yet technically simple strategy to enhance brain delivery of darunavir and potentially other lipophilic ARVs for treatment of HIV reservoir.

Wheel-Running Behavior Is Negatively Impacted by Zinc Administration in a Novel Dual Transgenic Mouse Model of AD

Alzheimer's disease (AD) is a neurocognitive disorder that impacts both the brain and behavior. Metal ions, including zinc (Zn), have been seen to play an important role in AD-related pathology. In this study, we show alterations in wheel-running behavior both early and late in disease progression in a novel dual Tg mouse model of AD. This mouse includes both amyloid and tau pathology through its cross with the J20 (hAPP) and P301L (Tau) parentage. Animals were given either lab water or water that had been supplemented with 10 ppm Zn. Wheel running was assessed through individually housing mice and measuring wheel-running activity in both the light and dark cycles. Dual Tg mice showed significantly less activity in the first part of the dark cycle than WT mice at both 3.5 and 7 months of age (p < 0.05). Dual Tg mice given Zn water showed less activity compared to dual Tg mice on lab water, tau mice on Zn water, or WT mice given either lab or Zn water (p < 0.05) at 7 months. Female mice in this study consistently showed higher activity compared to male mice in all groups whereas Zn led to reduced activity. Daily activity rhythm was altered in both the tau and dual Tg mice, and Zn impacted this alteration through effects on amyloid, tau, and through circadian pathways.