The vagus nerve and thirst

Abstract

This paper reviews the experiments, which demonstrate conclusively the involvement of the abdominal vagus nerve in normal expression of most aspects of thirst in rats, by Gerard P. Smith and his colleagues published between 1975 and 1984. The nature of that vagal contribution differs with the type of primary thirst signal. Thus, there is no clear or unitary answer concerning whether the contribution of the vagus nerve is purely sensory, or some general tonic action within the central nervous system. Subsequent studies using cFos mapping of intracellular dehydration in conjunction with vagotomy and/or hepatic manipulations are also reviewed and further illustrate the involvement of abdominal information, both in the initiation as well as the termination of drinking. Many of the questions that were raised by Smith during these pioneering studies remain unaddressed and unanswered.