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Estrogens, But Not Androgens, Regulate Expression and Functional Activity of Oxytocin Receptor in Rabbit Epididymis
- Source :
- Endocrinology. 143:4271-4280
- Publication Year :
- 2002
- Publisher :
- The Endocrine Society, 2002.
-
Abstract
- Previous binding and contractility studies indicate that oxytocin (OT) receptors are present in rabbit epididymis. To investigate the effect of changing endocrine milieu on OT responsiveness, we induced hypogonadism (hypo) in rabbits with a single administration of a long-acting GnRH analog, triptorelin, and we replaced hypogonadal rabbits with different sex steroids. After 2 months from triptorelin administration, testosterone (T) plasma levels were decreased and OT responsiveness abolished. Administration of T to hypo rabbits restored T plasma levels but not OT sensitivity. Because Western blot analysis indicated that both estrogen receptors and aromatase are expressed in the epididymis, we treated hypo rabbits with estradiol valerate (E2v). E2v not only completely restored OT responsiveness but also even amplified it. Accordingly, Northern and Western blot analysis indicated that both OT receptor gene and protein were strongly induced by E2v but not by T. Surprisingly, also the class I estrogen receptor antagonist, tamoxifen restored OT sensitivity in hypo rabbits. To verify whether endogenous estradiol is involved in the regulation of OT receptor responsiveness, we treated intact rabbits with an aromatase inhibitor, letrozole. Blocking aromatase activity almost completely abolished OT sensitivity. These findings suggest a new function of estrogens in the male: regulation of OT responsiveness in epididymis.
- Subjects :
- Male
medicine.medical_specialty
medicine.drug_class
Blotting, Western
Estrogen receptor
Oxytocin
Endocrinology
Internal medicine
Nitriles
medicine
Animals
Testosterone
RNA, Messenger
Enzyme Inhibitors
Aromatase
Receptor
Epididymis
Triptorelin Pamoate
Aromatase inhibitor
Estradiol
biology
Aromatase Inhibitors
Reverse Transcriptase Polymerase Chain Reaction
Hypogonadism
Estrogen Antagonists
Estradiol valerate
Estrogens
Triazoles
Blotting, Northern
Oxytocin receptor
Tamoxifen
Gene Expression Regulation
Receptors, Oxytocin
Estrogen
Letrozole
Androgens
biology.protein
Rabbits
medicine.drug
Subjects
Details
- ISSN :
- 19457170 and 00137227
- Volume :
- 143
- Database :
- OpenAIRE
- Journal :
- Endocrinology
- Accession number :
- edsair.doi.dedup.....82ca362919660320cc6f82958a21f911