engleski

Immobilization stress affects sialyltransferase activity in rat tissues

Excessive stress is one of the major problems in a modern society. A number of epidemiological and experimental studies clearly demonstrated a link between psychological stress and the development and course of many diseases, from simple virus infections and gastric ulcers, to cardiovascular diseases and cancer. Metabolic adaptation to adverse conditions is highly important for survival in ever-changing environment, but excessive activation of the stress response appears to be associated with various detrimental effects. However, exact molecular mechanisms that link psychological stress and the development of disease are still mostly elusive. Previously we have shown specific changes in protein glycosylation and expression of lectins that occur during the stress response. Here we report that stress also affects activity of sialyltransferases (STs). Using asialofetuin as an acceptor and 14C-CMP-NeuAc as a donor of sialic acid we have measured total ST activity in liver, kidney, heart, skeletal muscle, adrenal gland, medulla spinalis, hippocampus, cerebellum and cortex of rats exposed to immobilization stress, either acutely (one 2 h episode), or chronically (multiple immobilization, swim, and footshock stresses for eight days). Interestingly, despite the fact that all analyzed tissues were exposed to same hormonal signals, the impact of these signals on ST activity varied significantly. In liver and spleen acute stress caused approximately 40% increase in ST activity. However, when the exposure to stressors was prolonged, their effects in liver and spleen were opposite. While ST activity in spleen nearly doubled (193% of control), in liver it decreased to 82% of the activity in control rats. Beside in liver and spleen, ST activity in other analyzed non-neural tissues did not appear to be significantly influenced by stress. In neural tissues there was generally a reduction of ST activity as a consequence of stress. The only exception was the medulla spinalis where we did not observe any changes. Interestingly, despite significantly changed ST activity in some tissues, in the same tissues we did not observe any changes in sialoglycoprotein paterns.

stress; glycosyltransferases; sialyltransferase

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