Air Pollutant impacts on the brain and neuroendocrine system with implications for peripheral organs: a perspective

Abstract

Air pollutants are being increasingly linked to extrapulmonary multi-organ effects. Specifically, recent studies associate air pollutants with brain disorders including psychiatric conditions, neuroinflammation and chronic diseases. Current evidence of the linkages between neuropsychiatric conditions and chronic peripheral immune and metabolic diseases provides insights on the potential role of the neuroendocrine system in mediating neural and systemic effects of inhaled pollutants (reactive particulates and gases). Autonomically-driven stress responses, involving sympathetic-adrenal-medullary and hypothalamus-pituitary-adrenal axes regulate cellular physiological processes through adrenal-derived hormones and diverse receptor systems. Recent experimental evidence demonstrates the contribution of the very stress system responding to non-chemical stressors, in mediating systemic and neural effects of reactive air pollutants. The assessment of how respiratory encounter of air pollutants induce lung and peripheral responses through brain and neuroendocrine system, and how the impairment of these stress pathways could be linked to chronic diseases will improve understanding of the causes of individual variations in susceptibility and the contribution of habituation/learning and resiliency. This review highlights effects of air pollution in the respiratory tract that impact the brain and neuroendocrine system, including the role of autonomic sensory nervous system in triggering neural stress response, the likely contribution of translocated nano particles or metal components, and biological mediators released systemically in causing effects remote to the respiratory tract. The perspective on the use of systems approaches that incorporate multiple chemical and non-chemical stressors, including environmental, physiological and psychosocial, with the assessment of interactive neural mechanisms and peripheral networks are emphasized.

Keywords:

• Air pollution
• brain
• neuroendocrine
• systemic effects
• mechanisms
• initiating event

Acknowledgements

The authors thank Drs. Ian Gilmour, Andrew Ghio and Annie Jarabek of the US EPA and Dr. Jonathan Shannahan of the Purdue University for their critical review of the manuscript.

Disclaimer

The research described in this article has been reviewed by the Center for Public Health and Environmental Assessment, U.S. Environmental Protection Agency, and National Institute of Environmental Health Sciences, and approved for publication. Approval does not signify that the contents necessarily reflect the views and policies of the Agency, nor does the mention of trade names of commercial products constitute endorsement or recommendation for use.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

U.S. Environmental Protection Agency – Intramural