Following its successful January launch of the Early-Stage Investigator (ESI) Spotlight Webinar Series, the NIEHS Environmental Health Sciences Core Centers kept the momentum going on Feb. 9 with presentations on how early exposure to arsenic and lead can affect brain function.

Highlighting the outstanding research conducted by ESIs at all 26 institute-funded Core Centers is the goal of the webinar series. Mount Sinai Transdisciplinary Center on Early Environmental Exposures members Maria José Rosa, Dr.P.H., and Douglas Walker, Ph.D., host the monthly lectures.

Early-life lead exposure disrupts sleep

“Sleep is important for many facets of health in adolescence,” Jansen said. “But adolescents are among those most vulnerable to sleep deprivation.” (Photo courtesy of Erica Jansen)

The February event began with the presentation “Do Toxicants Affect Adolescent Sleep? Findings From the Early Life Exposures in Mexico to Environmental Toxicants (ELEMENT) Study,” by Erica Jansen, Ph.D. She is affiliated with the University of Michigan Lifestage Environmental Exposures and Disease Center.

• ELEMENT is a birth cohort that has been monitored for some 25 years.

• Jansen found associations between cumulative lead exposure in early childhood and shorter sleep duration in adolescence.

• “Those in the upper 25% of blood lead levels slept, on average, 23 minutes less than those in the lowest 25%,” she said. “A difference in sleep duration of 20 to 30 minutes is associated with clinically meaningful differences in cognition for adolescents.”

• “Short sleep duration has been associated with poor academic performance and mental health, higher rates of motor vehicle accidents, risky behavior, and lower immunity and poor diet,” Jansen added. She noted that some 60% of U.S. middle schoolers and 70% of U.S. high schoolers do not get adequate sleep.

• Jansen also discussed the relationship between cardiometabolic health and sleep. “Circadian rhythm disruption is related to higher blood pressure and higher markers of insulin resistance, particularly in adolescent females,” she said.

Healthy diets high in fruits, vegetables, and proteins are associated with earlier sleep onset, according to Jansen. Not surprisingly, coffee, tea, and soda were related to lower quality and shorter sleep duration.

Countering the effects of arsenic

“Disruption of neurodevelopment due to environmental exposures can have lifelong impacts,” said Park. (Photo courtesy of Hae-Ryung Park)

Hae-Ryung Park, Ph.D., presented “Mechanisms Underlying the Effect of Environmental Exposures on Neurodevelopment.” She is affiliated with the University of Rochester Environmental Health Sciences Center.

• Park noted that early-life exposure to arsenic has been linked to adverse neurodevelopmental outcomes, such as low IQ and impaired motor function.

• She found that microRNA-124 (miR-124), a molecule that is involved in brain function, can suppress arsenic-induced endoplasmic reticulum (ER) stress.

• The ER is a cell membrane system that produces proteins essential for cell function. An accumulation of unfolded or misfolded proteins results in ER stress, which can cause cell death. That stress has been associated with the development of metabolic diseases such as diabetes, obesity, and atherosclerosis.

• Park discovered that miR-124 diminished ER stress by targeting the IRE1 gene, which maintains ER function by activating what is called the unfolded protein response.

“Our study implicates arsenic-induced ER stress as a crucial mechanism for the detrimental effects of arsenic on neurodevelopment,” she said. “We identified miR-124 as a potential preventative and therapeutic target against the detrimental effects of arsenic exposure in children.”

(John Yewell is a contract writer for the NIEHS Office of Communications and Public Liaison.)