The proposed research is a continuation of experiments on mechanisms of temperature acclimation in freshwater fishes. It has been previously established that fish compensate for shifts to cold or warm temperature by changes in metabolism. Recently the applicant discovered that cultured liver cells can show compensatory changes in activities of enzymes but that these isolated liver cells fail to show the changes in capacity for protein synthesis that we have observed in vivo. The applicant proposes to test a variety of hormones for their effects on tissue cultures of fish liver cells. Previously, results indicate the region of the brain (preoptic hypothalamus) controlling behavioral temperature regulation in fish is the same region that integrates regulation in mammals. He hypothesizes that this same region of the brain senses temperature and triggers, probably via hormones, the compensatory changes in tissue metabolism. Two approaches are to be used. Lesions to the preoptic hypothalamus will be made under anesthesia and the fish allowed to recover. Preliminary evidence indicates that lesioned fish do not show the biochemical acclimation shown by the controls. He has previously recorded electrical activity in the hypothalamus and found temperature sensitive neurons. He plans to continue such recordings over longer times in an effort to learn the changes that occur when a fish adapts to an altered temperature. The proposed research has general significance with respect to adaptation of animals to environmental stress and concerning the temperature center in the brain.
