Alzheimer and depressive cognitive-like behaviors in male and female rats: A new method for exposure to ambient air pollution

In the previous studies regarding the effects of exposure to ambient air pollution on biological markers and/or behavior of animals, the gaseous pollutants are not separated from the particulate matter (PM). Hence the synergetic effect of gaseous pollutants and PM was not considered. In this regard, current study was aimed to devolve a new method for separation of PM from gaseous pollutants. Also, the effect of exposure to fine particulate matter (PM(2.5)) on the Alzheimer and depressive cognitive-like behaviors in rats after 3 and 6 months were investigated. Three chambers were designed including exposure group 1 (PM(2.5) plus gaseous pollutants alone), exposure group 2 (gaseous pollutants alone) and control group (clean air). Exposure time was 5 h per day (9.00 a.m.–2.00 p.m.) for 4 days per week. The concentration of PM(2.5) and gaseous pollutants (O(3), NO(2), and SO(2)) were monitored in the exposure hours, continuously. Concentration of PM(2.5) by beta attenuation method and concentration of O(3), NO(2), and SO(2) by UV fluorescence was monitored. Also, the concentration of metals including Al, Cr, Mn, Pb, Cd, Ni, Fe, and Cu and 16-polycyclic aromatic hydrocarbons (PAHs) bound PM(2.5) by inductively coupled plasma mass spectrometry (ICP-MS) and gas chromatography-mass spectrometry (GC—MS) were analyzed, respectively. Cognitive-like behavior related to Alzheimer and depressive behaviors were determined by Y maze and Force swimming. The concentration of PM(2.5) in the 3 and 6 months exposure was higher than WHO guideline, significantly (p-value <0.05). The concentration of O(3), NO(2) and SO(2) in the 3 and 6 months exposure was lower than WHO guideline, significantly (p-value <0.05). The order of metals in the PM(2.5) according to mean concentration Al > Ca > Cu > Cd > Na > Fe > Cr > Ni > Mn > Pb. Also, the sum concentration of 16-PAHs in the PM(2.5) in the 3 and 6 months exposure was 45.7 ± 37.15 ng/m(3) and 30.04 ± 25.27 ng/m(3), respectively. Exposure to PM(2.5) cannot significantly increase Alzheimer and depressive cognitive-like behaviors in the rats. Also, a significant difference between male and female in Alzheimer and depressive cognitive-like behaviors not observed. • A new method for separation of PM(2.5) from other PM in the ambient air by ECO-PM sampler was presented. • A new method for separation of PM(2.5) from gaseous pollutants in the ambient air by HEPA filter and active carbon was presented. • Tow exposure groups including exposure 1: PM(2.5) plus gaseous pollutants and exposure 2: gaseous pollutants only were designed for increased accuracy of the in-vivo study. • Exposure to PM(2.5) cannot cause significant increased Alzheimer and depressive cognitive-like behaviors in the rats.