Abstract:
:In hamsters, the Harderian glands (HGs) exhibit a marked sexual dimorphism which is thought to depend on dihydrotestosterone (DHT); however, it is unclear whether hamster HGs contain one or more 5 alpha-reductases and whether these enzymes are differentially expressed in males and females. In this study, we isolated specific cDNAs for 5 alpha-reductase 1 (Srd5a1) and 5 alpha-reductase 2 (Srd5a2), determined their sequences and investigated their expression in the HG of both sexes. Isozyme 1, cloned from liver mRNA, encodes a protein of 255 amino acids (aa); isozyme 2 cDNA, isolated from the epididymis encodes a 254-aa protein. When assayed in transfected HEK-293 cells, the type 1 isozyme displayed activity over a broad pH range (6.5-8), while isozyme 2 had a pH optimum of 5.5. Both isoenzymes efficiently catalyzed the in vitro transformation of T into DHT, with apparent K(m) values of 7.1 and 1.9 micromol/L for Srd5a1 and Srd5a2, respectively. Real-time PCR analysis revealed higher mRNA levels for Srd5a1 than for Srd5a2. Expression of both isoenzymes increased slightly in HGs of castrated males and showed variations during the estrous cycle in females. Hormonal replacement with 17beta-estradiol administered to spayed females induced the up-regulation of Srd5a2 mRNA levels. Altogether, our results demonstrated that both Srd5a1 and Srd5a2 are expressed in HGs without clear differences between males and females. The biochemical characteristics and relative expression of these 5 alpha-reductases support the view that both isozymes may play a relevant role in modulating androgen signaling in HG.
journal_name
Gen Comp Endocrinoljournal_title
General and comparative endocrinologyauthors
Ramos L,Chávez B,Vilchis Fdoi
10.1016/j.ygcen.2009.12.010subject
Has Abstractpub_date
2010-04-01 00:00:00pages
388-95issue
2eissn
0016-6480issn
1095-6840pii
S0016-6480(09)00437-7journal_volume
166pub_type
杂志文章abstract::The binding of 125I-labeled ovine prolactin (oPRL) to membrane preparations of tissue from freshwater-adapted tilapia (Sarotherodon mossambicus) was examined. Liver, ovary, and testis showed a relatively high specific binding (5-10%). A lower specific binding occurred consistently in intestine and gill tissue, and inc...
journal_title:General and comparative endocrinology
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journal_title:General and comparative endocrinology
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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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journal_title:General and comparative endocrinology
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journal_title:General and comparative endocrinology
pub_type: 杂志文章,评审
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pub_type: 杂志文章
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journal_title:General and comparative endocrinology
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journal_title:General and comparative endocrinology
pub_type: 杂志文章
doi:10.1006/gcen.1996.6802
更新日期:1997-01-01 00:00:00
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journal_title:General and comparative endocrinology
pub_type: 杂志文章
doi:10.1016/s0016-6480(03)00014-5
更新日期:2003-05-01 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:1989-03-01 00:00:00
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journal_title:General and comparative endocrinology
pub_type: 杂志文章
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journal_title:General and comparative endocrinology
pub_type: 杂志文章
doi:10.1016/j.ygcen.2004.09.010
更新日期:2005-01-01 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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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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journal_title:General and comparative endocrinology
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journal_title:General and comparative endocrinology
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journal_title:General and comparative endocrinology
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journal_title:General and comparative endocrinology
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journal_title:General and comparative endocrinology
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pub_type: 杂志文章,评审
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abstract::Growth hormone (GH) regulates essential physiological functions in teleost fishes, including growth, metabolism, and osmoregulation. Recent studies have identified two clades of putative receptors for GH (GHR1 clade and GHR2 clade) in fishes, both of which are highly expressed in the liver. Moreover, the liver is an i...
journal_title:General and comparative endocrinology
pub_type: 杂志文章
doi:10.1016/j.ygcen.2012.07.010
更新日期:2012-10-01 00:00:00
abstract::The insulin receptors of frog brain and liver show features typical of other insulin receptors with regard to affinity and specificity of binding to insulins and proinsulin, solubility in Triton X-100, binding to and elution from wheat germ agglutinin, and insulin-sensitive tyrosine kinase activity. Likewise, the brai...
journal_title:General and comparative endocrinology
pub_type: 杂志文章
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更新日期:1987-11-01 00:00:00
abstract::The present study examined plasma concentrations of insulin-like growth factor (IGF)-I, IGF-II and IGF-binding proteins (IGFBPs) during posthatch growth and development in chickens. Three distinct proteins which bound 125I-IGF-I were observed irrespective of age or sex, these having apparent molecular weights of 22, 2...
journal_title:General and comparative endocrinology
pub_type: 杂志文章
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