Neural regulation of inflammation: No neural connection from the vagus to splenic sympathetic neurons

Abstract

The 'inflammatory reflex' acts through efferent neural connections from the central nervous system to lymphoid organs, particularly the spleen, that suppress the production of inflammatory cytokines. Stimulation of the efferent vagus has been shown to suppress inflammation in a manner dependent on the spleen and splenic nerves. The vagus does not innervate the spleen, so a synaptic connection from vagal preganglionic neurons to splenic sympathetic postganglionic neurons was suggested. We tested this idea in rats. In a preparatory operation, the anterograde tracer DiI was injected bilaterally into the dorsal motor nucleus of vagus and the retrograde tracer Fast Blue was injected into the sple..