Alterations in the activities of subcellular fractions marker enzymes in rat liver and brain by hydrocortisone and corticosterone treatment

1. 1. The effect of subcutaneous injection of hydrocortisone and corticosterone on the activity values of some subcellular fractions marker enzymes from rat liver and brain was investigated and compared with controls (without treatment with hormones). 2. 2. The following enzymes were studied (subcellular fraction are shown between parentheses): N-acetyl-β- d-glucosaminidase and β-glucuronidase (lysosomes); succinate dehydrogenase = SDH (mitochondria); glucose-6-phosphatase (endoplasmic reticulum); 5′-nucleotidase and Na +K +Mg 2+ ATPase (plasma membrane). 3. 3. The specific activity of lysosomal enzymes from liver showed no change when rats were injected either with hydrocortisone or corticosterone. The same enzymes from brain showed significant increases in their activities with both hydrocortisone or corticosterone except β-glucuronidase; this enzyme gave activity values remaining between the control levels, after treatment with corticosterone. 4. 4. The activity of mitochondrial SDH was increased after corticosterone injection either in liver or brain. After hydrocortisone injection, its activity rises significantly in brain (72%), but it falls in liver compared to the control values. 5. 5. Glucose-6-phosphatase behaves similarly in brain or liver fractions; its activity increases always after corticosterone treatment and decreases by hydrocortisone. 6. 6. The plasma membrane marker enzymes did not change practically in brain fractions, excepted Na +K +Mg 2+ ATPase which tends to rise its activity after hydrocortisone injection. In liver fractions, both 5′-nucleotidase and Na +K +Mg 2+ ATPase activities increase either by corticosterone or hydrocortisone treatment, except 5′-nucleotidase which specific activity decreases in liver after hydrocortisone treatment.