Control/Tracking Number: 2025-A-1888-SOT

Selenium Pre-exposure Mitigates Cadmium-Induced Mechanosensation and Morphological Abnormalities in Larval Zebrafish, Though Visual Deficits Persist
 

Author Block:
J. Okutsu1, G. A. Guevara1, O. G. Umeh1, Z. Butler1, P. Silvera2, L. Kuker1, M. Deperalto1, R. R. Koop1, and D. S. Shelton1.
1 University of Miami, Coral Gables, FL; and 2 Miami Dade College, Miami, FL.
 

Abstract:
Background and Purpose:
Cadmium (Cd) is a persistent environmental toxicant ranked seventh among toxic substances by the Agency for ToxicSubstances and Disease Registry. Despite established thresholds, Cd causes adverse effects at low doses and accumulates in reproductive tissues, eyes,brains, and hearts. While selenium (Se) is an essential trace element known to prevent cognitive defects, its potential therapeutic effects against Cd toxicityremain unclear. Using zebrafish as a genetically tractable model with high physiological similarity to humans, this study examined whether Se pre-exposurecould mitigate Cd-induced developmental toxicity during early life stages.
 

Methods:
Zebrafish embryos were exposed to varying concentrations of Se (0, 10, 50, 100, 150, or 200 μg/L) for 1-4 days before transfer to Cd solutions (0,2.5, or 5 μg/L). Developmental endpoints were assessed at 5 days post fertilization. Hatch rate was evaluated on day 3. Morphological abnormalities were quantified by measuring trunk curvature and tail malformation incidence. Mechanosensation was assessed via tap response tests measuring distance moved, while vision was evaluated through white light response assays.
 

Results:
Pre-exposure to Se (10-200 μg/L) significantly improved hatch rates by day 3 compared to Cd-only exposure (78.5% vs 45.2%, p< 0.01) and reduced the incidence of trunk curvature (15.3% vs 42.7%, p< 0.01) and tail malformations (12.8% vs 28.4%, p < 0.04). Mechanosensory function, measured by distance moved after tap stimulus, showed comparable responses between Se→Cd treatments (11.8 ± 1.3 mm) and control fish (12.4 ± 1.2 mm, p> 0.05),indicating protective effects of Se. In contrast, visuomotor responses to white light stimuli were similarly impaired in both Se→Cd and Cd-only treatments (p> 0.05), indicating that selenium pre-exposure did not prevent cadmium-induced visual deficits.
 

Conclusions:
This study demonstrates that Se pre-exposure can mitigate several adverse developmental effects of Cd in zebrafish larvae, including delayed hatching, morphological abnormalities, and impaired mechanosensation, but not visuomotor deficits. The differential effects on various endpoints suggest distinct mechanisms of Se-mediated protection against Cd toxicity. These findings advance our understanding of mixed metal interactions in developmental toxicology and may inform therapeutic strategies for Cd exposure.

Category: Metals ; Neurotoxicity: Metals ; Neurotoxicity: Developmental

Keyword 1: Behavior
Keyword 2: Ocular Toxicity
Keyword 3: Neurotoxicity; Metals
Keyword Other: Selenium
Chemical Entity: Cadmium

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References:

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