Paternal intergenerational thyroid disruption in zebrafish induced by environmental prednisone exposure

Area of Science:

• Environmental toxicology
• Endocrinology
• Aquatic biology

Background:

• Environmental pollutants impact aquatic life and their progeny.
• Prednisone, a synthetic glucocorticoid, is found in surface waters and affects aquatic organisms.
• Limited data exists on prednisone's effects on zebrafish thyroid endocrine systems and intergenerational toxicity.

Purpose of the Study:

• To investigate the effects of environmentally relevant prednisone concentrations on the thyroid endocrine system of adult zebrafish (Danio rerio).
• To assess the intergenerational toxicity of prednisone exposure in zebrafish.
• To explore prednisone's impact on the hypothalamic-pituitary-thyroid (HPT) axis in parents and offspring.

Main Methods:

• Adult male zebrafish were exposed to prednisone concentrations ranging from 0-500 ng/L for 60 days.
• Evaluated physical parameters (body length, weight, swimming behavior) and plasma hormone levels (T3, T4, TSH).
• Analyzed thyroid histology, gene expression related to the HPT axis, and F1 larval development and survival.

Main Results:

• High prednisone doses reduced zebrafish body length, weight, and swimming speed.
• Observed significant alterations in parental thyroid hormones (decreased T4, increased T3 and TSH) and thyroid histology.
• Prednisone exposure led to increased F1 larval mortality, reduced hatching rates, abnormal heart rates, decreased swimming activity, and HPT axis gene dysregulation.

Conclusions:

• Prednisone induces intergenerational toxicity in zebrafish by disrupting thyroid endocrine function.
• The study confirms adverse effects on both parental and offspring generations through HPT axis disruption.
• Findings enhance understanding of prednisone's ecological risks to fish populations.