A preliminary investigation of the hormonal control of the hexose monophosphate oxidative pathway

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Abstract
Total levels of activity of both glucose-6-phosphate (G-6-P) and 6-phosphogluconate (6-PG) dehydrogenases are significantly reduced in the livers of rats maintained on restricted food intakes for 8 days and also after 48 hour starvation. Concentrations of both dehydrogenases are markedly re-duced in alloxan diabetes, total activities being only approximately 1/3 the control values. Thyroxine treatment results in an approximately 2-fold increase in the levels of activity of both dehydrogenases, whereas thiouracil treatment, although decreasing enzyme activities/g liver, does not significantly affect total liver values. Although long-term treatment with crystalline growth hormone causes some increase in G-6-P dehydrogenase activity/g liver, total liver-enzyme activities are not significantly affected. Liver-dehydrogenase concentrations show seasonal variations and are significantly higher in summer than in winter. Crystalline insulin, crystalline growth hormone and DL-thyroxine have no in vitro effect on either G-6-P or 6-PG dehydrogenase activity under conditions employed.