Initiation of eating as a function of ingestion of hypoosmotic solutions.

KAKOLEWSKI, JAN W., AND EDWARD DEAUX. hitiati~n of eating as a function of ingestion of hypoosmotic solutions. Am. J. Physiol. 218(2): 590495. 1970.--Factors involved in the initiation of food ingestion were investigated. The model used was based on an observation that, in rats kept under water deprivation conditions, ingestion of 3 ml or more of water results in initiation of food ingestion after a latency. Addition of glucose, saccharin, or NaCl to the water revealed that the latency to initiation of eating is an increasing function of the osmolality of the presented solution, and appears to be not solute specific. The rat’s ability to discriminate between the solution’s osmolality as measured by the initiation of food ingestion appears to be most sensitive to small differences in the low (hypoosmotic) range, Blood-composition measures revealed a significant decrease ih serum osmolality at the time of initiation of eating and an increase when the animal had an opportunity to ingest food for a short period. Animals in a state of decreased serum osmolality initiate food ingestion immediately on exposure to food. The possibility of a hypoosmotic cue in the initiation of food ingestion is discussed.