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
|