Enzyme activities in the androgenized rat uterus refractory to oestrogenic stimulation

Uterine enzymes involved in the intermediary metabolism of glucose have been measured in the androgenized rat in which there is evidence of diminution of the oestrogenic responses despite raised glycogen and glucose typical of maximal oestrogenic stimulation. Phosphofructokinase and isocitrate dehydrogenase (NADP, cytosolic) activities were significantly decreased in the androgenized rat and were elevated following treatment with natural progesterone and synthetic progestins which partially reverse the uterine abnormalities of the androgenized rat. Mitochondrial protein was decreased in the uterus of the androgenized rat but there was an apparent sparing effect on isocitrate (NAD) and malate (NAD) dehydrogenase. The data suggest that selective effects on specific enzymes involved in intermediary metabolism are a feature of the refractory state associated with constant oestrogenic stimulation. The possible cellular mechanisms underlying these effects are discussed.