TH and Parkinsonism: In support with previous studies demonstrating that inhaled toxins could cross the blood brain barrier, and that the damage in Parkinson’s could begin first in the olfactory bulb and then spread from there to the SN [13,14], we looked at TH-ir neurons and α-synuclein in the olfactory bulb and found loss of TH-ir neurons and enhanced α-synuclein expression around the olfactory bulb in LPS-treated mice.