Nanoplastics internalization impairs mitochondrial activity in equine sperm.
Abstract: Nanoplastics (NP) accumulation in biological tissues and their adverse effects on fertility through inflammatory and oxidative stress responses have recently been described as consequences of global plastic pollution. However, little is known about the impact of NP on gametes. This study aimed to assess the internalization of NP and their effects on mature equine spermatozoa. Frozen-thawed ejaculates from five stallions were divided into untreated control (CTR) and samples supplemented with different concentrations (10, 50, 100 and 200 μg/mL) of 30 nm polystyrene NP. At baseline (T0), and after 1 (T1) and 3 h (T3) of incubation at 38 °C, sperm viability, mitochondrial activity, and intracellular ROS were evaluated by flow cytometry, while sperm motility was assessed using a CASA system. NP internalization was analyzed by confocal microscopy and flow cytometry using fluorescent NP. Results showed that NP were internalized by live spermatozoa, accumulating in the post-acrosomal and/or the mid piece region. NP exposure led to reduced sperm viability (CTR T1: 50.7 ± 14.0 % vs 200 μg/mL T1: 36.6 ± 11.8 %, p<0.05), decreased mitochondrial activity (CTR T1: 35.4 ± 15.8 % vs 200 μg/mL T1: 16.3 ± 14.0 %, p<0.001), and increase proportions of live sperm with high intracellular O· levels (CTR T1: 39.0 ± 10.1 % vs 200 μg/mL T1: 47.3 ± 11.0 %, p<0.05). These results allow us to conclude that equine sperm quality may be compromised by nanoplastics internalization, which pre-eminently impairs mitochondrial activity. This research furnishes some bases for further studies on the potential implications of NP exposure for fertility.
Copyright © 2025 The Authors. Published by Elsevier Inc. All rights reserved.
Publication Date: 2025-10-14 PubMed ID: 41101066DOI: 10.1016/j.theriogenology.2025.117711Google Scholar: Lookup
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- Journal Article
Summary
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Overview
- This study investigated how nanoplastics (NP) enter horse sperm cells and the negative effects this internalization has on sperm function, particularly focusing on mitochondrial activity, viability, and oxidative stress.
Background
- Nanoplastics (NP) are tiny plastic particles resulting from the breakdown of larger plastic waste.
- NP contamination is widespread in the environment and is known to accumulate in biological tissues.
- Previous research has shown NP can cause fertility problems through inflammation and oxidative stress in tissues.
- However, the direct impact of NP on gametes (sperm and eggs) is not well understood.
Research Objective
- To determine whether nanoplastics are internalized by mature equine sperm cells.
- To assess how NP exposure affects sperm viability, mitochondrial function, intracellular reactive oxygen species (ROS), and motility.
Methods
- Frozen-thawed ejaculates from five stallions were used as samples.
- Sperm samples were divided into a control group (no NP) and groups exposed to varying concentrations of 30 nm polystyrene NP (10, 50, 100, 200 μg/mL).
- Sperm were incubated at 38°C and assessed at baseline (T0), after 1 hour (T1), and after 3 hours (T3).
- Sperm viability, mitochondrial activity, and intracellular ROS levels were measured using flow cytometry techniques.
- Sperm motility was analyzed using a Computer Assisted Sperm Analysis (CASA) system.
- Internalization of fluorescently labeled NP was confirmed by confocal microscopy and flow cytometry.
Findings
- Nanoplastics were found inside live sperm cells, accumulating mainly in the post-acrosomal region (near the sperm head) and/or the midpiece (region with mitochondria).
- Exposure to higher NP concentrations led to a significant decrease in sperm viability:
- At 1 hour, control viability was about 50.7%, whereas 200 μg/mL NP treatment dropped viability to 36.6%.
- There was a marked reduction in mitochondrial activity with NP exposure:
- At 1 hour, mitochondrial activity decreased from 35.4% in controls to 16.3% at the highest NP dose.
- Intracellular reactive oxygen species (ROS), specifically oxygen radicals, increased in live sperm exposed to NP:
- At 1 hour, control samples showed 39% of live sperm with high ROS, increasing to 47.3% in the 200 μg/mL NP group.
- These changes indicate oxidative stress and mitochondrial impairment due to NP internalization.
Conclusions and Implications
- The study demonstrates that nanoplastics can enter horse sperm and accumulate in regions critical for sperm function.
- This internalization negatively impacts sperm quality by reducing viability and mitochondrial activity and increasing oxidative stress.
- Because mitochondria are essential for sperm energy production and motility, NP exposure may impair fertility.
- This research provides foundational data to further explore how environmental exposure to nanoplastics could threaten reproductive health in animals and potentially in humans.
Cite This Article
APA
Dindo S, Tovar-Pascual L, Baldassarro VA, Bucci D, Mislei B, Spinaci M, Ortiz-Rodriguez JM.
(2025).
Nanoplastics internalization impairs mitochondrial activity in equine sperm.
Theriogenology, 250, 117711.
https://doi.org/10.1016/j.theriogenology.2025.117711 Publication
Researcher Affiliations
- Department of Veterinary Medical Sciences, Alma Mater Studiorum-University of Bologna, Via Tolara di Sopra 50, Ozzano dell'Emilia, Bologna, 40064, Italy.
- Department of Veterinary Medical Sciences, Alma Mater Studiorum-University of Bologna, Via Tolara di Sopra 50, Ozzano dell'Emilia, Bologna, 40064, Italy.
- Department of Veterinary Medical Sciences, Alma Mater Studiorum-University of Bologna, Via Tolara di Sopra 50, Ozzano dell'Emilia, Bologna, 40064, Italy.
- Department of Veterinary Medical Sciences, Alma Mater Studiorum-University of Bologna, Via Tolara di Sopra 50, Ozzano dell'Emilia, Bologna, 40064, Italy.
- Department of Veterinary Medical Sciences, Alma Mater Studiorum-University of Bologna, Via Tolara di Sopra 50, Ozzano dell'Emilia, Bologna, 40064, Italy; National Institute of Artificial Insemination (AUB-INFA), University of Bologna, Via Gandolfi 16, Cadriano, Bologna, 40057, Italy.
- Department of Veterinary Medical Sciences, Alma Mater Studiorum-University of Bologna, Via Tolara di Sopra 50, Ozzano dell'Emilia, Bologna, 40064, Italy.
- Department of Veterinary Medical Sciences, Alma Mater Studiorum-University of Bologna, Via Tolara di Sopra 50, Ozzano dell'Emilia, Bologna, 40064, Italy. Electronic address: jose.ortiz@unibo.it.
MeSH Terms
- Animals
- Male
- Horses
- Spermatozoa / drug effects
- Spermatozoa / physiology
- Mitochondria / drug effects
- Mitochondria / physiology
- Microplastics / toxicity
- Sperm Motility / drug effects
- Nanoparticles / toxicity
Conflict of Interest Statement
Declaration of interests The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
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