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The effects of androgens on the bioactivity and molecular composition of pituitary FSH were examined in intact and GnRH antagonist-suppressed male rats. Eight groups of adult Sprague-Dawley rats were subjected to the following treatments: antagonist (75 micrograms/day by osmotic minipumps; sc), testosterone-filled Silastic implants (3 X 5 cm, sc), dihydrotestosterone-filled Silastic implants (3 X 5 cm, sc), E2 benzoate (15 micrograms/day, sc), and combined administration of antagonist with either steroid for 3 weeks. At the end of the treatment period, pituitaries were dissected out and homogenised. FSH content was determined in the pituitary extracts by an in vitro bioassay and a radioimmunoassay. Individual pituitary extracts from rats treated with vehicle, testosterone and testosterone + antagonist were subjected to isoelectric-focusing on sucrose density gradients performed in the pH range from 3.5 to 7.0. Individual isoelectric-focusing fractions (100-120) were analysed for bioactive and immunoreactive FSH. Treatment with antagonist, E2 or antagonist + E2 caused a significant decrease in pituitary FSH, whereas testosterone and dihydrotestosterone alone or in combination with antagonist prevented the decrease in pituitary FSH. The effects of all treatments on both bioactive and immunoreactive FSH were similar. Testosterone treatment not only maintained FSH synthesis but also altered the molecular composition of pituitary FSH. Following treatment with testosterone there was a shift of maximal FSH bioactivity to the more acidic pH range. On the other hand, less bioactivity was recovered than corresponding immunoreactivity in the higher pH region, resulting in significantly reduced ratios of bioactivity to immunoreactivity of FSH.(ABSTRACT TRUNCATED AT 250 WORDS)
O P Sharma, and
S A Khan, and
G F Weinbauer, and
M Arslan, and
E Nieschlag
December 1986,
Acta endocrinologica,
O P Sharma, and
S A Khan, and
G F Weinbauer, and
M Arslan, and
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January 1986,
Acta endocrinologica. Supplementum,
O P Sharma, and
S A Khan, and
G F Weinbauer, and
M Arslan, and
E Nieschlag
January 1967,
Proceedings of the Society for Experimental Biology and Medicine. Society for Experimental Biology and Medicine (New York, N.Y.),
O P Sharma, and
S A Khan, and
G F Weinbauer, and
M Arslan, and
E Nieschlag
May 1971,
Endocrinology,
O P Sharma, and
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G F Weinbauer, and
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January 2006,
Journal of andrology,
O P Sharma, and
S A Khan, and
G F Weinbauer, and
M Arslan, and
E Nieschlag
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Journal of steroid biochemistry,
O P Sharma, and
S A Khan, and
G F Weinbauer, and
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E Nieschlag
June 1974,
Acta endocrinologica,
O P Sharma, and
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G F Weinbauer, and
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E Nieschlag
May 1994,
The Journal of endocrinology,
O P Sharma, and
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G F Weinbauer, and
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January 1988,
The American journal of physiology,
O P Sharma, and
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G F Weinbauer, and
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