Hatano Research Institute, Food and Drug Safety Center, Hadano, Kanagawa, Japan
Description:
In 1985 two lines of Sprague-Dawley were selectively bred for their active shuttle-box avoidance task which is a device used for evaluating the effects of chemicals in pharmacological and toxicological studies and testing learning behavior of animals. These animals have a higher rate of avoidance response and showed little interindividual variation.
ACTH and prolactin synthesis in the anterior pituitary was significantly higher than LAA under stress conditions which states that the response of hypothalamo-pituitary axis to acute restraint stress is greater in HAA as compared to LAA.
These have lighter pituitary glands and ovaries as compared to the LAA rats, whereas the uterine weights and adrenal gland weights are higher than the LAA rats.
HAA rats show a regular 4-day estrous cycle. The level of preovulatory luteinizing hormone (LH) surge level is significantly higher than the LAA rats on the day of proestrus.