Hypophysectomy and the structure of exploratory behavior in the rat

Abstract

Chronically maintained hypophysectomized or sham-operated adult male Sprague/2-Dawley rats were exposed to a novel environment and their activity patterns were recorded for 4 hr. A comparison of behavior across groups indicated an increase in exploration for the experimental rats. Further analysis revealed changes in activity consistent with disrupted habituation. This was also confirmed with a second exposure to the testing environment. This may reflect disrupted consolidation of the stimulus and motivational properties of the new environment on the part of the hypophysectomized rats. The present findings are consistent with previous reports on the role of pituitary hormones in learning, and extend previous studies to a novel paradigm.