Abstract：
:The activity of the enzyme steroid 5 alpha-reductase in Harderian glands of adult syrian hamsters was assessed by measuring the conversion of testosterone (T) to 5 alpha-dihydrotestosterone (DHT). The optimal conditions for this reaction were determined in vitro using whole gland homogenates and [3H]testosterone as substrate. Enzyme activity was maximal at pH 5.5. The Michaelis-Menten constant of the Harderian enzyme for T was 4.6 +/- 1.2 x 10(-6) M in females and 4.2 +/- 0.39 x 10(-6) M in males, estimated by Eadie-Hofstee plots. On the basis of relative maximum velocity values, there was 9 or 10 times more 5 alpha-reductase in females (2.8 +/- 0.67 nmol/mg protein/hr) than in males (0.289 +/- 0.029 nmol/mg protein/hr). Consistently, glands of intact male hamsters had lower 5 alpha-reductase activities than those of females. Castration of males significantly increased the enzymatic activity, which within 4 weeks reached female-like values. The levels of 5 alpha-reductase mRNA also increased with castration. There was a direct correlation between activity and mRNA levels of the enzyme in castrated male glands. Further, the administration of T or DHT to ovariectomized hamsters led to intact male values in the enzymatic activity of the gland. The sex differences in 5 alpha-reductase activity may be of relevance to the differential regulation exerted by androgen upon the physiology of male and female glands. The results are consistent with the view that 5 alpha-dihydrotestosterone is the active androgen in the Harderian gland.
journal_name
Gen Comp Endocrinoljournal_title
General and comparative endocrinologyauthors
Vilchis F,Enriquez J,Queipo G,Pérez-Palacios G,Chávez Bdoi
10.1006/gcen.1994.1185subject
Has Abstractpub_date
1994-11-01 00:00:00pages
298-308issue
2eissn
0016-6480issn
1095-6840pii
S0016648084711853journal_volume
96pub_type
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journal_title：General and comparative endocrinology
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journal_title：General and comparative endocrinology
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更新日期：1993-10-01 00:00:00
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journal_title：General and comparative endocrinology
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journal_title：General and comparative endocrinology
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更新日期：1987-02-01 00:00:00
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journal_title：General and comparative endocrinology
pub_type： 杂志文章
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journal_title：General and comparative endocrinology
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更新日期：2001-06-01 00:00:00
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更新日期：2015-02-01 00:00:00
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更新日期：1991-02-01 00:00:00
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journal_title：General and comparative endocrinology
pub_type： 杂志文章
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journal_title：General and comparative endocrinology
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更新日期：2011-02-01 00:00:00
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journal_title：General and comparative endocrinology
pub_type： 杂志文章
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更新日期：2008-10-01 00:00:00
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journal_title：General and comparative endocrinology
pub_type： 杂志文章
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更新日期：2009-01-15 00:00:00
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journal_title：General and comparative endocrinology
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更新日期：2000-01-01 00:00:00
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journal_title：General and comparative endocrinology
pub_type： 杂志文章
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更新日期：1996-01-01 00:00:00
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journal_title：General and comparative endocrinology
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更新日期：1990-09-01 00:00:00
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journal_title：General and comparative endocrinology
pub_type： 杂志文章
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更新日期：2004-03-01 00:00:00
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journal_title：General and comparative endocrinology
pub_type： 杂志文章
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更新日期：1996-09-01 00:00:00
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journal_title：General and comparative endocrinology
pub_type： 杂志文章
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更新日期：2020-05-15 00:00:00
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journal_title：General and comparative endocrinology
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