Neural route of pyrogen signaling to the brain.

In the pathogenesis of systemic inflammation and fever, peripheral inflammatory and pyrogenic signals gain access to the brain via humoral and neural routes. One of the neural routes is represented by chemosensitive afferent fibers of the abdominal vagus. We summarize our recent studies of the role of the abdominal vagus in fever. We conclude that capsaicin-sensitive fibers traveling within the hepatic vagal branch constitute a necessary component of the afferent mechanism of the febrile response to low, but not high, doses of circulating pyrogens. We speculate that this mechanism is triggered by blood-borne prostaglandins of the E series.