Regulation of Glucose-6-phosphatase Activity

Regulation of Glucose-6-phosphatase Activity 1. Introductory Remarks 

An attempt is made in this section to present the few established facts relating to the hormonal and dietary regulation of liver G-6-Pase activity. 

It should be noted that in instances of reported changes in G-6-Pase activity resulting from hormone administration or removal, special experimental conditions may be necessary to obtain clear-cut effects (Weber and Cantero, 1957c) (see Fig. 2). The basis on which the enzymatic activity is expressed may be of great importance, because of the possible change in liver weight and in liver body weight ratio under the experimental circum- 

Injection of hydrocortisone (1 mg. perday) in hypophysectomized animals caused a definite increase in liver G-6-Pase activity (Harper, 1956). 

Effect on adrenalectomy in diabetic animals. Adrenalectomy in alloxan diabetics rats returned liver G-6-Pase activity to normal. That this effect was due to the absence of adrenal cortical hormone was evidenced by the increase in G-6-Pase in the adrenalectomized diabetic rats to diabetic levels, 218% of normal, by injection of 17-hydroxycorticosterone (5 mg, per 12 hours) over a 48-hour period (Ashmore et al., 1956b). It was also shown that in adrenalectomized animals insulin injection caused a more marked drop in liver G-6-Pase activity than in normal animals (Ashmore et al., 1956b). 

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