[Abstract Title]. - Society for Neuroscience

Authors: *R. KVETNANSKY 1 , M. NOVAKOVA 2 , J. PETRAK 3 , O. KRIZANOVA 4 , J.
MYSLIVECEK 2 , A. TILLINGER 3 ;
1 Inst. Exp Endocrinol, Slovak Acad. Sci., Bratislava, Slovakia; 2 First Fac. of Medicine, Charles
Univ., Prague, Czech Republic; 3 Inst. of Exptl. Endocrinology, SAS, Bratislava, Slovakia; 4 Inst.
of Mol. Physiol. and Genetics, SAS, Bratislava, Slovakia
Abstract: Catecholamines (norepinephrine-NE and epinephrine-EPI) are among the first
circulating compounds released during stress response of the organism. They prepare heart to
“fight or flight” situation via stimulation of β-adrenoceptors (β-ARs). There are only few papers
dealing with changes of cardiac β-ARs in stress situations. The aim of the present work was to
measure gene expression, protein levels and binding sites of β-ARs in the heart of rats exposed to
acute and repeated immobilization (IMO) stress. Single and repeated IMO significantly increased
EPI conc. in the heart ventricles, while NE was only slightly changed. We found a significant
decrease of β2-AR mRNA, protein levels and binding sites in the left ventricle of animals
exposed mainly to repeated IMO stress. These changes were not accompanied by similar changes
in the right ventricle. No significant changes of β1-AR gene expression and proteins were
observed in ventricles of rats exposed both, to a single or repeated IMO. The most interesting
changes were found in β3-AR mRNA levels, proteins and binding sites, which were significantly
increased in the left ventricle especially of repeatedly IMO rats. As by β2-AR, the changes of β3-
AR were not observed in right ventricle. Taken together, we found decreased number of cardiostimulating
β2-AR and increased number of cardio-inhibitive β3-AR in the left ventricle of
repeatedly stressed rats. Moreover, repeated stress substantially reduced the basal and forskolinstimulated
adenylyl cyclase activity in left ventricles. Our results suggest that maintaining of
cardiac homeostasis under stress conditions is achieved by balance among the β-AR. We have
demonstrated ventricle specific changes in β2- and β3-AR gene expression, which is probably
related to different physiological function of ventricles. This is the first report showing on
molecular genetic level the importance of cardiac β3-AR receptors coping with stress.
Disclosures: R. Kvetnansky, None; M. Novakova, None; J. Petrak, None; O. Krizanova,
None; J. Myslivecek, None; A. Tillinger, None.
Poster
282. Stress and the Brain: Cellular Actions of Stress
Time: Sunday, November 16, 2008, 1:00 pm - 5:00 pm
Program#/Poster#: 282.12/OO19
Topic: E.06.d. Cellular actions of stress
Support: Lundbeck Inc.