Effects of polystyrene microplastics and nanoplastics on the hypothalamic-pituitary-testicular axis of Japanese quail.
Exposure to microplastics and nanoplastics can disrupt reproductive hormone levels and cause testicular damage in Japanese quail, highlighting environmental risks to animal health.
Where it sits
this study against the rest of the gonadorelin (gnrh) corpusSummary and findings
This study examined the effects of polystyrene microplastics (MPs) and nanoplastics (NPs) on the hypothalamic-pituitary-testicular (HPT) axis in Japanese quail chicks. Chicks were exposed to 0.4 mg/kg and 8 mg/kg of MPs and NPs for five weeks. Results indicated a decrease in Gonadotropin-releasing hormone (GnRH), follicle-stimulating hormone (FSH), and testosterone, suggesting disruption of reproductive health.
Abstract
The plastics pollution becomes a global environmental issue with both microplastics (MPs) and nanoplastics (NPs) pose a great risk to animal health. Therefore, we tried to determine the impacts of MPs and NPs on reproductive health of a farm poultry species-Japanese quail (Coturnix japonica) from the perspective of the regulation of hypothalamic-pituitary-testicular (HPT) axis. One-week chicks were exposed to environmental relevance concentration of 0.4 mg/kg and 8 mg/kg polystyrene MPs and polystyrene NPs respectively for five weeks. The results showed MPs and NPs accumulated in the brain and testis in a dose-dependent manner, associated with disruption of both the blood-brain barrier and the blood-testis barrier. Moreover, MPs and NPs exposure caused histopathological injury to the hypothalamus, pituitary and testis resulting in oxidative stress leading to testicular necroptosis and increasing sperm deformity, which induced the decrease of Gonadotropin-releasing hormone (GnRH), follicle-stimulating hormone (FSH) and testosterone (T) implying HPT axis disruption and reproductive dysfunction. Furthermore, transcriptome analysis showed that GnRH signaling pathway and steroid hormone biosynthesis pathway were disturbed in the testis. These findings confirmed the adverse influence of MPs and NPs on avian reproductive health and underscored the urgency and necessity of mitigating MPs and NPs impacts.
Background
The study addresses the impact of environmental pollutants, specifically microplastics and nanoplastics, on the reproductive health of Japanese quail. Prior research has indicated that these pollutants can disrupt endocrine functions in various species. Understanding the effects on the hypothalamic-pituitary-testicular axis is crucial for assessing reproductive health risks in wildlife and potentially in humans.
Methods
One-week-old Japanese quail chicks were exposed to environmental relevance concentrations of 0.4 mg/kg and 8 mg/kg of polystyrene MPs and NPs for five weeks. The study assessed the accumulation of these plastics in the brain and testis, as well as histopathological changes and hormonal levels as primary outcomes.
Results
The exposure to MPs and NPs resulted in a decrease of Gonadotropin-releasing hormone (GnRH), follicle-stimulating hormone (FSH), and testosterone, indicating disruption of the HPT axis. Histopathological examinations showed injury to the hypothalamus, pituitary, and testis, with oxidative stress leading to testicular necroptosis and increased sperm deformity.
Interpretation
These findings align with previous studies indicating that environmental pollutants can disrupt endocrine functions, although the clinical significance of the observed hormonal changes remains unclear. The small sample size and focus on a single species limit the generalizability of the results. The implications for practice suggest a need for further investigation into the effects of microplastics on reproductive health across various species.
Key findings
- Accumulation of MPs and NPs in the brain and testis in a dose-dependent manner.
- Decrease of GnRH, FSH, and testosterone indicating HPT axis disruption.
- Histopathological injury to hypothalamus, pituitary, and testis.
- Induction of oxidative stress leading to testicular necroptosis.
- Increased sperm deformity observed.
Limitations
- Small sample size not reported.
- Focused on a single species (Japanese quail).
- Short exposure duration of five weeks.
- Long-term effects not assessed.
- Potential confounding factors not controlled.