Developmental exposure to concentrated ambient particles and preference for immediate reward in mice.
BACKGROUND
Recent epidemiological studies indicate negative associations between a diverse group of air pollutants and cognitive functioning in children and adults, and aspects of attention deficit in children. Neuroinflammation and oxidative stress are two putative biological mechanisms by which air pollutants may adversely affect the brain.


OBJECTIVE
We sought to determine whether exposure to concentrated ambient particulate matter (CAPS) during the first 2 weeks of life, alone or again in adulthood, could alter responding for delayed reward, a critical component of human decision making. Greater preference for immediate reward has been implicated as a component of several psychiatric disorders, addiction, obesity, and attention deficit.


METHODS
C57BL/6J mice were exposed to ultrafine particles (< 100 nm in aerodynamic diameter; CAPS) using the Harvard University Concentrated Ambient Particle System (HUCAPS) or filtered air in the postnatal period (days 4-7 and 10-13) with and without adult exposure over days 56-60. In adulthood, delay behavior was assessed using a fixed-ratio waiting-for-reward (FR wait) paradigm in which 25 responses (FR25) were required to initiate the waiting-for-reward component during which mice obtained "free" sucrose pellets with the stipulation that these "free" pellets were delivered at increasing delay intervals.


RESULTS
Coupled with increased FR response rates, mice exposed to postnatal CAPS displayed increased FR resets that reinstated short delays, indicating a preference for shorter delays, despite the added response cost of the FR25. No associated changes in locomotor activity were observed.


CONCLUSIONS
Postnatal CAPS exposure produces an enhanced bias towards immediate rewards, a risk factor for several central nervous system (CNS) disorders. This enhancement does not appear to be the result of hyperactivity. The findings underscore the need for further evaluation of air pollution effects on the CNS and its potential contribution to CNS diseases and disorders.
Department of Environmental Medicine, University of Rochester School of Medicine, Rochester, New York 14642, USA.
Joshua L
JL
Allen
Katherine
K
Conrad
Günter
G
Oberdörster
Carl J
CJ
Johnston
Brianna
B
Sleezer
Deborah A
DA
Cory-Slechta
D000393:Air Pollutants / Q000633:toxicity*; D000397:Air Pollution / Q000009:adverse effects; D000818:Animals; D003657:Decision Making / Q000187:drug effects; D051379:Mice; D008810:Mice, Inbred C57BL; D018384:Oxidative Stress / Q000187:drug effects; D052638:Particulate Matter / Q000633:toxicity*
D000393:Air Pollutants; D052638:Particulate Matter