Bacterial lipopolysaccharide induces a conduction block in the sciatic nerves of rats

A single injection of Escherichia coli lipopolysaccharide (LPS; intraperito neally [i.p.] and intravenously [i.v.]) reliably induces peripheral nerve d isturbances in the hindlimbs of inbred Australian albino Wistar (AaW) rats. In the series of experiments presented here, we aimed to characterize this syndrome by examining electrophysiologic, immunologic, and immunochemical features. The LPS-induced neurologic sequelae in AaW rats were transient, a t least partly reversible by drug treatment, and were not associated with a ny detectable neuropathologic findings by light microscopy, Neurologic sequ elae were prevented by administration of dexamethasone and by pretreatment with the macrophage inhibitor gadolinium chloride, suggesting that they wer e caused by LPS-induced activation of peripheral macrophages. Sequelae were associated with early decreases in compound muscle-action potential amplit udes, indicating impaired functioning of either proximal sciatic nerve axon s and/or neuromuscular synapses, Spinal somatosensory-evoked potential late ncies also were increased, indicating impaired somatosensory function at th e sciatic nerve, dorsal roots, spinal cord, and/or postsynaptic interneuron s, although the precise location of impairment could not be delineated, Sim ilarities between this syndrome and immune-mediated polyneuropathies in hum ans are discussed.