ABSTRACT
Particular emphasis has been laid on a role of peripheral sensory cues that may affect the hypothalamic control mechanism mediating body fluid homeostasis. Thus, the nucleus of the solitary tract (NTS) has attracted considerable interest since primary afferents from these peripheral osmoreceptors project directly to the NTS. A small implanted stimulating electrode was hooked to the vagal branch for electrical stimulation; field-evoked potentials were then recorded from the brainstem in rats to determine onto which region the hepatic vagal branch projects. Relatively little is known concerning brainstem mechanisms mediating osmotic sensation. Also, knowledge of a reflex center located in the brainstem that participates in fluid homeostasis is scanty. A possible role of the brainstem as a reflex center in fluid homeostasis may involve control of water and ion absorption from the intestine. Much more physiological and behavioral evidence is necessary to complete our understanding of the mechanisms of fluid homeostasis mediated by the brainstem.
