Effect of subchronic exposure to ambient fine and ultrafine particles on rat motor activity and ex vivo striatal dopaminergic transmission.

Alterations in dopaminergic transmission are associated with neurological disorders, such as depression, autism, and Parkinson's disease. Exposure of rats to ambient fine (FP) or ultrafine (UFP) particles induces oxidative and inflammatory responses in the striatum, a neuronal nucleus with dense dopaminergic innervation and critically involved in the control of motor activity.Objectives: We used an ex vivo system to evaluate the effect of in vivo inhalation exposure to FP and UFP on motor activity and dopaminergic transmission.Materials and Methods: Male adult Wistar rats were exposed to FP, UFP, or filtered air for 8 weeks (subchronic exposure; 5 h/day, 5 days/week) in a particle concentrator. Motor activity was evaluated using the open-field test. Uptake and release of [3H]-dopamine were assessed in striatal synaptosomes, and dopamine D2 receptor (D2R) affinity for dopamine was evaluated by the displacement of [3H]-spiperone binding to striatal membranes.Results: Exposure to FP or UFP significantly reduced spontaneous motor activity (ambulatory distance: FP -25%, UFP -32%; ambulatory time: FP -24%, UFP -22%; ambulatory episodes: FP -22%, UFP -30%), decreased [3H]-dopamine uptake (FP -18%, UFP -24%), and increased, although not significantly, [3H]-dopamine release (113.3 ± 16.3 and 138.6 ± 17.3%). Neither FP nor UFP exposure affected D2R density or affinity for dopamine.Conclusions: These results indicate that exposure to ambient particulate matter reduces locomotion in rats, which could be related to altered striatal dopaminergic transmission: UFP was more potent than FP. Our results contribute to the evidence linking environmental factors to changes in brain function that could turn into neurological and psychiatric disorders.HIGHLIGHTSYoung adult rats were exposed to fine (FP) or ultrafine (UFP) particles for 40 days.Exposure to FP or UFP reduced motor activity.Exposure to FP or UFP reduced dopamine uptake by striatal synaptosomes.Neither D2R density or affinity for dopamine was affected by FP or UFP.UFP was more potent than FP to exert the effects reported.

Seasonal and Spatial Variability of PM2.5 Concentration, and Associated Metal(loid) Content in the Toluca Valley, Mexico.

This study provides evidence of the seasonal and spatial variation of metal(lloid)s in particulate matter minor to 2.5 microns (PM2.5) in the Toluca Valley Metropolitan Area (TVMA), the fifth largest urban center in Mexico. Four sites were sampled between 2013 and 2014, which included urban and industrial areas, in the dry-cold (November-February) and dry-hot (March-May) seasons; PM2.5 was collected using high- and medium-volume samplers. Metal(lloid) concentrations in PM2.5 were analyzed using inductively coupled plasma‒mass spectrometry (ICP‒MS). The highest 24-hour PM2.5 concentration in the northern area was observed, and the PM2.5 concentrations were independent of the season. Five metal(lloid)s with a recovery percentage above 80% were considered to be reported (Co, Cr, Cu, Mn, and Sb). The maximum concentrations of metal(lloid)s were observed during the dry-cold season, and concentrations were up to one hundred or thousand fold with respect to the dry-hot season. The 24-hour PM2.5 and metal(lloid) concentrations exceeded national and international guidelines to protect population health.

In vitro exposure to ambient fine and ultrafine particles alters dopamine uptake and release, and D2 receptor affinity and signaling.

The exposure to environmental pollutants, such as fine and ultrafine particles (FP and UFP), has been associated with increased risk for Parkinson's disease, depression and schizophrenia, disorders related to altered dopaminergic transmission. The striatum, a neuronal nucleus with extensive dopaminergic afferents, is a target site for particle toxicity, which results in oxidative stress, inflammation, astrocyte activation and modifications in dopamine content and D2 receptor (D2R) density. In this study we assessed the in vitro effect of the exposure to FP and UFP on dopaminergic transmission, by evaluating [3H]-dopamine uptake and release by rat striatal isolated nerve terminals (synaptosomes), as well as modifications in the affinity and signaling of native and cloned D2Rs. FP and UFP collected from the air of Mexico City inhibited [3H]-dopamine uptake and increased depolarization-evoked [3H]-dopamine release in striatal synaptosomes. FP and UFP also enhanced D2R affinity for dopamine in membranes from either rat striatum or CHO-K1 cells transfected with the long isoform of the human D2R (hD2LR)2LR). In CHO-K1-hD2L In CHO-K1-hD2LR cells or striatal slices, FP and UFP increased the potency of dopamine or the D2R agonist quinpirole, respectively, to inhibit forskolin-induced cAMP formation. The effects were concentration-dependent, with UFP being more potent than FP. These results indicate that FP and UFP directly affect dopaminergic transmission.

Evaluation of the effect of an environmental management program on exposure to manganese in a mining zone in Mexico.

BACKGROUND: In the state of Hidalgo, Mexico, is found the largest second deposit of Manganese (Mn) in Latin America. Various studies on the sources of emission, exposure, and the effects on the health of children and adults have been conducted utilizing an ecosystem approach. Given the findings of Mn levels in air and the neurocognitive effects, an Environmental Management Program (EMP) was designed and implemented with the purpose of reducing exposure to Mn of the population, including various actions for reducing Mn emissions into the atmosphere. OBJECTIVE: To evaluate the impact of the EMP on the concentrations of Mn in air, as well as the modification of exposure to Mn in the blood and hair of adult residents of the communities intervened. METHODS: A quasi-experimental study was conducted in five rural communities, in which Mn concentrations were evaluated in air and in blood in the years 2002 and 2007, pre-intervention, and in 2013, postintervention. In 2003, the concentration of hair Mn among the communities was evaluated. Measurements were carried out of Particulate Matter (PM) of >10 and 2.5µm (PM10 and PM2.5), and Mn in PM10 and PM2.5 were measured using proton-induced X-ray emissions (PIXE). The method of Difference in Differences (DID) was applied to estimate the impact of EMP on Mn concentrations in particulate matter via linear regression through multilevel models. To evaluate the effect of Mn concentrations in air over Mn concentrations in blood in both study periods in the mining communities per year (2002 and 2013), a linear regression model for each year was employed. RESULTS: We estimated that the EMP contributed to reducing the average daily concentrations of Mn in PM10 and PM2.5 by 92 and 85%, respectively. The adjusted model did not show an effect of Mn concentrations in air over Mn concentrations in blood in both study periods. CONCLUSIONS: The results suggest that the measures implemented to reduce Mn emissions in air exerted a significant impact on the reduction of inhaled exposure in adult population.