Enhancement of α-adrenoceptor-mediated responses in prostate of testosterone-treated rat
| Autor: | Poduri Ramarao, Chaman Lal Kaul, Meenakshisundaram Thiyagarajan |
|---|---|
| Rok vydání: | 2002 |
| Předmět: |
Male
medicine.medical_specialty Tetrahydronaphthalenes Injections Subcutaneous Rats Sprague-Dawley Xylazine Phenylephrine Internal medicine medicine Prazosin Animals Testosterone Receptor Adrenergic alpha-Antagonists Pharmacology Dose-Response Relationship Drug business.industry Imidazoles Prostate Muscle Smooth Receptors Adrenergic alpha Rats Guanfacine Clonidine Endocrinology Mechanism of action medicine.symptom business Adrenergic alpha-Agonists Muscle Contraction medicine.drug |
| Zdroj: | European Journal of Pharmacology. 453:335-344 |
| ISSN: | 0014-2999 |
| DOI: | 10.1016/s0014-2999(02)02452-4 |
| Popis: | The present study was undertaken to investigate the effect of testosterone on the alpha-adrenoceptor-mediated contractile responses in ventral lobe of rat prostate. Contractile responses to various alpha-adrenoceptor agonists (phenylephrine, A61603 (N-[5-(4,5-dihydro-1H-imidazol-2-yl)-2-hydroxy-5,6,7,8-tetrahydronaphthalen-1-yl] methanesulphonamide), clonidine, guanfacine, ST587 ((2,3-dihydro-benzo[1,4]dioxin-2-ylmethyl)-[2-(2,6-dimethoxy-phenoxy)-ethyl]-amine) and xylazine) were tested in prostate strips obtained from control and testosterone (3 mg/kg, s.c. 5 days a week for 15 days-10 doses total)-treated rats. Dose-response curves for alpha-adrenoceptor agonists in testosterone-treated animals showed a leftward shift, indicating increased sensitivity of tissue to alpha-adrenoceptor agonists. To find the mechanism of increased sensitivity, K(A) value and receptor reserve of phenylephrine were estimated. Neither the K(A) value nor the receptor reserve of phenylephrine was altered in testosterone-treated rats. The concentration-occupancy curve for A61603 was shifted leftward and the K(A) value for A61603 decreased about four-fold. The K(B) value of 2-(2,6-dimethoxyphenoxyethyl) aminomethyl-1,4-benzodioxane (WB4101) was not altered, however, the K(B) value for prazosin was decreased approximately 5.5-fold. These findings indicate that the testosterone-mediated increase in sensitivity of prostate to alpha-adrenoceptor agonists is due to alterations in the alpha(1)-adrenoceptor pool. |
| Databáze: | OpenAIRE |
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