INHIBITION OF THE RAT ADRENAL ORNITHINE DECARBOXYLASE ACTIVITY BY IMMOBILIZATION STRESS AND OR DEXAMETHASONE/

The effects of immobilization stress and/or dexamethasone (DEX) on the adrenal ornithine decarboxylase (ODC) activities of sham-operated and adrenal-medulloectomized (enucleated) male Sprague-Dawley rats were i nvestigated. On day 11 after surgery, rats were injected with saline o r DEX (1 mg/kg), 3 h before the time of sacrifice (0600 h or 1800 h). Four groups, from sham-operated and enucleated rats (ENU) treated with saline or DEX were subjected to immobilization stress far 1 h prior t o sacrifice. Groups of rats from stress-sham-DEX, non stress-sham-DEX, stress-sham, non stress-sham, stress-ENU-DEX, non stress-ENU-DEX, str ess-ENU, and non stress-ENU were sacrificed at 0600 h or 1800 h on day 11 after surgery. Adrenal glands were excised and later analyzed for ODC activities. Results indicated that DEX and/or immobilization stres s inhibited ODC activities (p<0.05) in normal and regenerating adrenal glands at 1800 h and ODC activity varies diurnally, the activity bein g greater at 1800 h than at 0600 hours (p<0.001).