Catecholamines and sympathomimetic drugs decrease early Salmonella Typhimurium uptake into porcine Peyer's patches

Peyer's patches of the small intestine serve as inductive sites for mucosal immunity as well as targets for invasive enteropathogens, including Salmonella. Because they are innervated by catecholamine-containing enteric nerves, the hypothesis that the endogenous catecholamines dopamine and norepinephrine or sympathomimetic drugs alter Salmonella Typhimurium uptake into Peyer's patches was tested. Porcine jejunal Peyer's patch explants were mounted in Ussing chambers and inoculated with a porcine field isolate of Salmonella Typhimurium DT104. Salmonella recovery from gentamicin-treated tissues increased significantly between 30 and 90 min of bacterial exposure to the mucosal surface. Addition of the neuronal conduction blocker saxitoxin (0.1 μmol L^-1) or dopamine (30 μmol L^-1) to the contraluminal aspect of explants decreased bacterial recovery after 60 min of Salmonella exposure. The effects of dopamine were mimicked by cocaine and methamphetamine (30 μmol L^-1), which act on catecholaminergic nerve terminals to increase synaptic neurotransmitter concentrations. These results suggest that enteric catecholaminergic nerves modulate Salmonella colonization of Peyer's patches at the earliest stages of infection, in part by altering epithelial uptake of bacteria.