17β-Hydroxysteroid dehydrogenase activity in the pituitary gland and neural tissue of rhesus monkeys

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Abstract

Ovariectomized rhesus monkeys were treated with estradiol-17β (E2) for 24 days; E2 for 24 days and progesterone (P) for the last 12 days; or P alone for 12 days. Parts of the brain (hypothalamus, preoptic area, amygdala, frontal cortex, and cerebellum) and anterior pituitary gland were analyzed for activity of the 17β-hydroxy steroid dehydrogenase (17β-HSDH) by quantification of the amount of [14C]-estrone (14C-E1) or [3H]-androstenedione ([3h]-a) formed from [14C]-E2 or [3H]-testosterone ([3H]-T) by minced tissue in a 2-h incubation period at pH 7.4. No significant effect of treatment was observed. Therefore, the between treatment data were pooled and analyzed together. The anterior pituitaries, both in the amount of [14C]-E1 formed from [14C]-E2 and in the amount of [3H]-A formed from [3H]-t, had a significantly higher level of enzyme activity (P < 0.001) than any of the neural tissue analyzed.

The difference between the activity of the 17β-HSDHs in anterior pituitary and brain tissue was confirmed after we incubated the 800 g supernatant of these tissues and used radioimmunoassayable E1 as an end point of 17β-HSDH activity. With this technique, the activity was lost after freezing, was greater at pH 8.0 than at 7.0, and was linear at protein concentrations from 0.3 to 1.0 mg/ml of incubation medium. The fact that this enzyme is localized with such intensity within the anterior pituitary may indicate that it participates in E2 action at the pituitary level in this species.

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