Abstract
Adrenomedullin (ADM) has been shown to be present in the human and rat male reproductive systems. This study demonstrates the expression of ADM in the rat testis and its effect on the secretion of testosterone. Whole testicular extracts had 5.43 +/- 0.42 fmol of immunoreactive ADM per milligram of protein and 84 +/- 8 fg of ADM mRNA per picogram of Actb (beta-actin) mRNA. Immunocytochemical studies showed positive ADM immunostaining in the Leydig cells and in the Sertoli cells. Gel filtration chromatography of testicular extracts showed two peaks, with the predominant one eluting at the position of the ADM precursor. Furthermore, the testis was shown to coexpress mRNAs encoding the calcitonin receptor-like receptor and receptor activity modifying protein 1 (Ramp1), Ramp2, and Ramp3. These account for the specific binding of ADM to the testis, which was partially inhibited by human ADM (22-52) and by human calcitonin gene-related peptide (8-37), the ADM and calcitonin gene-related peptide receptor antagonists, respectively. Administration of ADM to testicular blocks in vitro resulted in a dose-dependent inhibition of hCG-stimulated release of testosterone, which was abolished by the administration of ADM (22-52). Our results suggest a paracrine effect of ADM on testicular steroidogenesis.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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Adrenomedullin / genetics*
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Adrenomedullin / metabolism
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Adrenomedullin / pharmacology
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Animals
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Binding Sites
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Calcitonin Receptor-Like Protein
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Chorionic Gonadotropin / pharmacology
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Chromatography, Gel
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Dose-Response Relationship, Drug
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Gene Expression Regulation
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In Vitro Techniques
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Intracellular Signaling Peptides and Proteins / genetics*
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Male
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Membrane Proteins / genetics*
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Rats
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Rats, Sprague-Dawley
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Receptor Activity-Modifying Protein 1
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Receptor Activity-Modifying Protein 2
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Receptor Activity-Modifying Protein 3
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Receptor Activity-Modifying Proteins
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Receptors, Adrenomedullin
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Receptors, Calcitonin / genetics
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Receptors, Calcitonin / metabolism
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Receptors, G-Protein-Coupled / genetics*
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Receptors, G-Protein-Coupled / metabolism
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Testis / drug effects
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Testis / metabolism*
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Testosterone / metabolism*
Substances
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CALCRL protein, human
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Calcitonin Receptor-Like Protein
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Calcrl protein, rat
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Chorionic Gonadotropin
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Intracellular Signaling Peptides and Proteins
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Membrane Proteins
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RAMP1 protein, human
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RAMP2 protein, human
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RAMP3 protein, human
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Ramp1 protein, rat
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Ramp2 protein, rat
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Ramp3 protein, rat
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Receptor Activity-Modifying Protein 1
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Receptor Activity-Modifying Protein 2
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Receptor Activity-Modifying Protein 3
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Receptor Activity-Modifying Proteins
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Receptors, Adrenomedullin
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Receptors, Calcitonin
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Receptors, G-Protein-Coupled
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adrenomedullin receptor, rat
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Adrenomedullin
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Testosterone