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.