The early time course (1, 3, 9, 24 h) of changes in rates of protein synthesis (ks) in liver and three different muscles (gastrocnemius, soleus and heart) was investigated after injection of saline, interleukin-1 beta (IL-1) or turpentine in rats. IL-1 injection induced a consistent increase in body temperature of about 3 degrees C between 3 and 5 h, but thereafter a hypothermic response occurred. With turpentine, a delayed fever response with a peak value by 9 h was observed. Both IL-1 and turpentine had no effect on protein synthesis in the small intestine, but produced a significant increase in ks in the liver at 9 h. By 24 h in IL-1-treated animals, liver ks had returned back to control values, whereas the turpentine-treated group showed a progressive rise in ks. Gastrocnemius and soleus muscles exhibited a significant fall in ks at 9 h after IL-1 and turpentine injection compared with the control. In contrast, the ks of heart muscle increased at 3-9 h after IL-1 injection, but there was no effect of turpentine. Thus for the first time a marked decrease of protein synthesis in skeletal muscle in response to IL-1 could be demonstrated.
