Physiol. Res. 52: 67-72, 2003

Different Activation of ACTH and Corticosterone Release in Response to Various Stressors in Rats


J. DJORDJEVIĆ, G. CVIJIĆ, V. DAVIDOVIĆ

Institute of Physiology and Biochemistry, Faculty of Biology, University of Belgrade, Belgrade, Yugoslavia
 

Received February 5, 2002
Accepted May 4, 2002


Summary
The aim of this study was to investigate the reaction of the hypothalamo-pituitary-adrenocortical (HPA) system to various stressors (fasting, crowding, cold and heat) by measuring blood ACTH and corticosterone (CORT) concentration as well as the cholesterol (CHOL) content in the adrenals. To examine the effects of stress termination, the rats were returned and kept under control conditions for the same period as that of stress duration (supposed recovery period). According to our results HPA system was activated by all the stressors applied. Heat seems to be the strongest stressor since the exposure of animals to a high ambient temperature resulted in the greatest rise of plasma ACTH concentration as well as CORT synthesis and secretion. These values remained elevated after the stress termination i.e. after the rats had been returned to room temperature. Fasting seems to be the weakest stressor given because it causes the smallest increase in blood ACTH and CORT concentrations. Moreover, in refed rats the HPA function was fully recovered. In conclusion, the various stressors applied seem to induce a different response of the HPA system as judged by quantitative changes in ACTH and CORT release.


Key words
ACTH • Cholesterol • Corticosterone • Stress


Reprint requests
Jelena Djordjevic, Institute of Physiology and Biochemistry, Faculty of Biology, University of Belgrade, Studentski Trg 16, PO Box 52, 11000 Belgrade, Yugoslavia. Fax: +381 11 639064, E-mail: jelenadj@bf.bio.bg.ac.yu


© 2003 by the Institute of Physiology, Czech Academy of Sciences