MOLECULAR CAUSES OF CHANGES IN SENSITIVITY OF ADENYLYL CYCLASE SIGNALING SYSTEM TO BIOGENIC AMINES IN THE
HEART MUSCLE DURING EXPERIMENTAL STREPTOZOTOCIN DIABETES
A. O. Shpakov,1 L. A. Kuznetsova,1 S. A. Plesneva,1
I. A. Guryanov,2 M. N. Pertseva 1
1 Sechenov Institute of Evolutionary Physiology and Biochemistry, RAS, and
2 Institute of Macromolccular Compounds, RAS, St. Petersburg, Russia;
e-mail: alex_shpakov@list.ru
Changes in hormonal sensitivity of the adenylyl cyclase signaling system (ACS) and their possible molecular
causes in the heart muscle of rats with experimental streptozotocin diabetes (type I diabetes) are investigated. An increase in
stimulating effects of noradrenaline and isoproterenol on adenylyl cyclase (AC) activity have been shown. In the case of
noradrenaline, this increase is due to suppression of Gi-protein function and Gi-coupled inhibitory AC
signaling pathway. Meanwhile, in diabetic rats the influence of C-terminal peptide 346-355 of αi2-subunit on
hormonal activation of AC and GTP-binding is diminished. In the case of isoproterenol, along with its stimulating effect, at
micromolar concentrations this hormone exerts inhibitory action, realized, presumably, through pVadrenergic receptors. Effect of
isoproterenol on AC and GTP-binding in the heart of diabetic animals is modified by peptide 385-394 αs, blocking
Gs-coupled signaling pathways, and by peptide 346-355 αi2, blocking transduction of inhibitory signals.
In addition, a decrease in serotonin stimulating effect on components of ACS in diabetic animals was shown. The data obtained
provide evidence for changes in ACS function in diabetes, which can be detected mainly at the G-protein level. The proposed
peptide strategy is a new and perspective approach for studying molecular causes of functional violations in hormonal signaling
systems arising at endocrine pathology.
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