THE EFFECT OF HOUSING CONDITIONS AND SIMPLE EXPERIMENTAL PROCEDURES UPON THE CORTICOSTERONE LEVEL IN THE PLASMA OF RATS

Abstract

SUMMARY: The concentration of corticosterone in the plasma of rats has been determined by a spectrophotofluorimetric method. Animals housed in single cages, undisturbed for 18 hr. prior to testing show reproducible levels of 5·5 μg./100 ml. plasma. Rats housed in groups of 20 under the same conditions exhibit mean levels of 9·5 μg./100 ml. Non-specific stimuli such as environmental change, noise, handling, weighing and intraperitoneal injections all produce marked increases in plasma corticosterone levels which remain supernormal for at least 2 hr. The variation in the literature reports of 'resting' plasma corticosterone levels is discussed in the light of the present findings.