Tropospheric ozone effect on olfactory perception and olfactory bulb dopaminergic interneuron excitability.

Ozone (O) forms in the Earth's atmosphere, both naturally and by reactions of man-made air pollutants. Deleterious effects of O have been found in the respiratory system. Here, we examine whether O alters olfactory behavior and cellular properties in the olfactory system. For this purpose, mice were exposed to O at a concentration found in highly polluted city air [0.8 ppm], and the behavior elicited by social and non-social odors in habituation/dishabituation tests was assessed. In addition, the electrical responses of dopaminergic olfactory bulb (OB) neurons were also evaluated. O differentially compromises olfactory perception to odors: it reduces responses to social and non-social odors in Swiss Webster mice, while this effect was observed in C57BL/6 J mice only for some non-social odors. Additionally, O reduced the rate of spontaneous spike firing in periglomerular dopaminergic cells (PG-DA) of the OB. Because this effect could reflect changes in excitability and/or synaptic inputs, the ability of O to alter PG-DA spontaneous activity was also tested together with cell membrane resistance, membrane potential, rheobase and chronaxie. Taken together, our data suggest the ability of O to affect olfactory perception.