Early weaning PCB 95 exposure alters the neonatal endocrine system: thyroid adipokine dysfunction

Area of Science:

• Endocrinology
• Environmental Toxicology
• Developmental Biology

Background:

• Polychlorinated biphenyls (PCBs) are persistent environmental pollutants known to disrupt endocrine function.
• The endocrine-disrupting potential of specific PCB congeners, like PCB 95, requires further investigation, particularly during critical developmental windows.

Purpose of the Study:

• To investigate the effects of early-life exposure to PCB 95 on the hypothalamic-pituitary-thyroid (HPT) axis in male rats.
• To assess the impact of PCB 95 on thyroid hormone levels, thyroid gland histology, and related metabolic parameters.

Main Methods:

• Early-weaned male rats were administered a single dose of PCB 95 (32 mg/kg) on postnatal days 15 and 16.
• Serum hormone concentrations (thyroid hormones, TSH, GH, leptin, adiponectin, TNF, IGF1, insulin) and body weight were measured at postnatal days 17 and 18.
• Thyroid gland histopathology was examined at postnatal day 18.

Main Results:

• PCB 95 exposure significantly reduced thyroxine, triiodothyronine, and GH levels, while increasing TSH concentrations.
• Histopathological examination revealed thyroid gland deterioration, including follicular degeneration, edema, and fibrosis.
• PCB 95 exposure led to altered levels of adipokines and growth factors, and a significant decrease in body weight.

Conclusions:

• Early-life exposure to PCB 95 disrupts the developmental HPT axis, leading to hypothyroidism and associated metabolic disturbances.
• PCB 95-induced hypothyroidism may negatively impact the adipokine axis, fat metabolism, and overall postnatal development.
• Further research is warranted to fully elucidate the long-term consequences of PCB 95 exposure on developmental processes.