Surfactants selectively ablate enteric neurons of the rat jejunum

Surfactants, a group of nonspecific membrane perturbating substances, can cause nerve damage. Various concentrations of the cationic surfactants benzalkonium chloride (BAC) and benzethonium chloride, the anionic surfactants sodium ricinoleate, dioctyl sodium sulfosuccinate and sodium lauryl sulfate and the nonionic surfactant Triton X-100 were applied to the serosal surface of the rat jejunum every 5 min for 0.5 hr and then rinsed off with saline. Thirty days after surfactant application, the treated and an untreated segment of jejunum were removed and examined histologically. All surfactants which were tested significantly reduced the number of ganglion cells in the myenteric plexus. In addition, sodium ricinoleate significantly reduced the number of ganglion cells in the submucosal plexus. Higher concentrations of the cationic agents BAC and benzethonium chloride caused a generalized tissue damage including disruption of the smooth muscle, lymphocytic infiltration, intestinal perforation and death. Using BAC as a prototype surfactant, peptidergic neuron distribution and gut electrical activity were examined. BAC treatment markedly reduced the immunoreactivity of somatostatin, substance P, met-enkephalin and vasoactive intestinal peptide in the myenteric plexus. In addition, the electric properties of the smooth muscle were altered. BAC treatment resulted in an erratic, markedly distorted basic electric rhythm and an alteration in spike potential generation. These studies demonstrate that surfactants in appropriate concentrations selectively ablate the myenteric neurons and alter peptidergic neuron distribution and gut electrical parameters in the rat jejunum.