Chronic postnatal DE-71 exposure: effects on learning, attention and thyroxine levels

Area of Science:

• Environmental Toxicology
• Developmental Neurotoxicity
• Flame Retardant Chemicals

Background:

• Polybrominated diphenyl ethers (PBDEs) are widespread, bioaccumulative flame retardants with largely unknown chronic developmental toxicological effects.
• Understanding the long-term impacts of PBDE exposure, particularly during development, is crucial for public health.
• The commercial pentaBDE mixture DE-71 is a common source of human exposure.

Purpose of the Study:

• To investigate the chronic developmental toxicological effects of PBDEs on learning and attention in male Long-Evans rats.
• To assess the impact of PBDE exposure on the cholinergic system's response to scopolamine.
• To compare the effects of chronic developmental exposure to DE-71 with those of acute exposure.

Main Methods:

• Male Long-Evans rats were exposed to the pentaBDE mixture DE-71 from birth through lactation and direct diet.
• Adult rats underwent behavioral testing using five-choice serial reaction time tasks to assess learning and attention.
• Thyroxine levels were measured, and rats were challenged with the muscarinic antagonist scopolamine.

Main Results:

• Chronic DE-71 exposure significantly reduced serum total thyroxine (T4) levels.
• Impairments in sustained attention and inhibitory control were observed in rats exposed to 4.5 mg/day DE-71.
• DE-71 exposure did not alter visual discrimination learning or the response to scopolamine challenge.

Conclusions:

• Chronic developmental exposure to DE-71 leads to specific deficits in attention and inhibitory control in adult rats.
• These findings suggest that chronic exposure models are more environmentally relevant for assessing PBDE developmental toxicity.
• Further research is warranted to elucidate the mechanisms underlying PBDE-induced neurobehavioral effects.