Relation between glucocorticoid level and hepatic glutamic dehydrogenase activity

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Abstract
The relationship between the glucocorticoid level and hepatic glutamic dehydrogenase (GDH) activity in rats was investigated. Significant elevations in hepatic GDH activity resulted from daily injection of 2 or 5 mg cortisol/rat. The time course of the responses to these dosages differed markedly. Two milligrams cortisol per day induced elevations which were maintained for 7 days. The 5-mg dose stimulated a rapid increase for 48 hr. but the 7th day the activity had decreased to control levels. Adrenalectomy resulted in a significant decrease in hepatic GDH activity. Daily cortisol (1 mg) administration to adrenalectomized rats not only prevented this decrease but induced activities significantly higher than in sham-operated controls. Equimolar amounts of corticosterone, cortisol, and triamcinolone had quantitatively similar effects on hepatic GDH activity. Deoxycorticosterone was ineffective. The observed relationship between the glucocorticoid level and hepatic GDH activity suggests that the oxidative deamination of glutamate may be of major importance in catabolic conditions leading to gluconeogenesis and increased formation of urea.