RNA polymerase and ribonuclease activities in skeletal muscle of prednisolone-treated rats
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Abstract:
Nuclei isolated from gastrocnemius muscles of rats given prednisolone acetate i.p. showed decreased levels of Mg2ł-dependent RNA polymerase activity while the Mn2+-dependent polymerase activity showed no significant change from control levels. Both acid and alkaline ribonuclease activities in gastrocnemius and liver of prednisolone-treated rats were lower than levels in untreated rats. Although evidence was obtained for the existence of an inhibitor of ribonuclease activity in skeletal muscle, the effect of the glucocorticoid on ribonuclease activity was not due to increased levels of any such inhibitor.
Insights
Prednisolone acetate treatment in rats decreased RNA polymerase activity in muscle nuclei and lowered ribonuclease activity in muscle and liver tissues. These changes were not caused by an increase in ribonuclease inhibitors.
Area of Science:
- Biochemistry
- Molecular Biology
- Pharmacology
Background:
- Glucocorticoids like prednisolone acetate are potent anti-inflammatory agents.
- Understanding their molecular mechanisms in muscle and liver is crucial for therapeutic applications.
Purpose of the Study:
- To investigate the effects of prednisolone acetate on RNA polymerase and ribonuclease activities in rat skeletal muscle and liver.
- To determine if changes in ribonuclease activity are mediated by inhibitors.
Main Methods:
- Isolation of nuclei from rat gastrocnemius muscles and liver.
- Assay of Mg2+-dependent and Mn2+-dependent RNA polymerase activities.
- Measurement of acid and alkaline ribonuclease activities.
- Investigation of potential ribonuclease inhibitor involvement.
Main Results:
- Prednisolone acetate significantly decreased Mg2+-dependent RNA polymerase activity in muscle nuclei.
- Mn2+-dependent RNA polymerase activity remained unchanged.
- Both acid and alkaline ribonuclease activities were reduced in gastrocnemius muscle and liver.
- No evidence suggested that increased ribonuclease inhibitor levels accounted for the observed decrease in ribonuclease activity.
Conclusions:
- Prednisolone acetate alters nucleic acid metabolism in rat skeletal muscle and liver.
- The drug reduces RNA polymerase and ribonuclease activities.
- The observed effects on ribonuclease are independent of alterations in ribonuclease inhibitor levels.