Gulf War illness (GWI) is a chronic, multi-symptom disorder with no treatment. Exposure to anti-cholinergic drugs such as pyridostigmine bromide (PB) contributed to the development of GWI, but the mechanisms that connect the acute effects of PB with chronic dysfunction in multiple systems remain unclear. Gastrointestinal problems are frequent and debilitating chronic symptoms experienced by Gulf War veterans. The overall objective of this proposal is to understand how PB contributes to the development of functional gastrointestinal disorders in Gulf War illness. Given that the enteric nervous system (ENS) regulates gut functions, we hypothesize that that PB disrupts gut functions by creating persistent neuroinflammation within the ENS. The major activities in this reporting period include in vivo and in vitro studies to understand the acute effects of PB on the ENS, the neural control of gut functions, and the inflammatory response within the gut.