UP-REGULATION OF PKA RI-ALPHA SUBUNIT MESSENGER-RNA IN RAT SKELETAL-MUSCLE AFTER NERVE INJURY

LOCALIZATION of all subunits of cAMP dependent protein kinase (PKA) mR NAs and their changes of expression after denervation were examined in rat tongue skeletal muscle by in situ hybridization histochemistry. A mong all PKA subunits only RI alpha subunit mRNA was detected in the s keletal muscle, whereas positive signal of all subunits mRNA were obse rved in some haematocytes or lymphocytes within the tongue tissue. The RI alpha mRNA was distributed in a restricted area near the endplate. The mRNA level was substantially induced by the hypoglossal nerve tra nsection, suggesting that the up-regulation of RI alpha mRNA leading t o the down-regulation of PKA activity may contribute to some intracell ular signalling modulation or to muscle specific gene transcription af ter the denervation.