| 1. |
- Bauer, Ricarda M., et al.
(författare)
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Coupling of α1-adrenoceptors to ERK1/2 in the human prostate
- 2011
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Ingår i: Urologia internationalis. - : S. Karger AG. - 0042-1138 .- 1423-0399. ; 86:4, s. 427-433
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Tidskriftsartikel (refereegranskat)abstract
- INTRODUCTION: α1-Adrenoceptors are considered critical for the regulation of prostatic smooth muscle tone. However, previous studies suggested further α1-adrenoceptor functions besides contraction. Here, we investigated whether α1-adrenoceptors in the human prostate may activate extracellular signal-regulated kinases (ERK1/2). METHODS: Prostate tissues from patients undergoing radical prostatectomy were stimulated in vitro. Activation of ERK1/2 was assessed by Western blot analysis. Expression of ERK1/2 was studied by immunohistochemistry. The effect of ERK1/2 inhibition by U0126 on phenylephrine-induced contraction was studied in organ-bath experiments. RESULTS: Stimulation of human prostate tissue with noradrenaline (30 μM) or phenylephrine (10 μM) resulted in ERK activation. This was reflected by increased levels of phosphorylated ERK1/2. Expression of ERK1/2 in the prostate was observed in smooth muscle cells. Incubation of prostate tissue with U0126 (30 μM) resulted in ERK1/2 inhibition. Dose-dependent phenylephrine-induced contraction of prostate tissue was not modulated by U0126. CONCLUSIONS: α1-Adrenoceptors in the human prostate are coupled to ERK1/2. This may partially explain previous observations suggesting a role of α1-adrenoceptors in the regulation of prostate growth.
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| 2. |
- Gratzke, Christian, et al.
(författare)
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Transient Receptor Potential A1 and Cannabinoid Receptor Activity in Human Normal and Hyperplastic Prostate: Relation to Nerves and Interstitial Cells
- 2010
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Ingår i: EUROPEAN UROLOGY. - : Elsevier BV. - 0302-2838 .- 1873-7560. ; 57:5, s. 902-910
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Tidskriftsartikel (refereegranskat)abstract
- Background: Ion channel transient receptor potential A1 (TRPA1) and cannabinoid (CB) receptors are involved in mechanoafferent signaling from the bladder and the urethra. Objective: To characterize TRPA1-, CB1-, and CB2-receptor activities in the human prostate. Design, setting, and participants: Prostate specimens were obtained from 12 patients undergoing radical prostatectomy. We studied expressions (n = 6) of TRPA1, CB1, and CB2 receptors and effects of the TRPA1 agonists allyl isothiocyanate (AI), cinnamaldehyde (CA), sodium hydrogen sulfide (NaHS), and CP 55940 (a CB1/CB2 agonist) on prostatic preparations. Measurements: Western blot, immunohistochemistry, and functional experiments were performed. Results and limitations: Western blot detected expected bands for CB1, CB2, and TRPA1. TRPA1 immunoreactivity was located on nerves that were positive for CB1, CB2, calcitonin gene-related peptide (CGRP), nitric oxide synthase (NOS), or vesicular acetylcholine transporter (VAChT). CB1 and CB2 immunoreactivity was found on nerves that were positive for NOS, VAChT, or CGRP. Adrenergic nerves were not immunoreactive for TRPA1, CB1, or CB2. In nodular hyperplasia, nerves containing the above markers were scarce or absent. TRPA1 immunoreactivity was detected in cyclic guanosinemonophosphate-positive basal cells of the glandular epithelium. Basal or subepithelial TRPA1-immunoreactive cells contained vimentin and c-kit immunoreactivity. CA and NaHS relaxed precontracted preparations by 55 +/- 7% and 35 +/- 3% (n = 6 for each). CP 55940, NaHS, AI, capsaicin, and CA decreased nerve contractions up to 27%, 80%, 47%, and 87%, respectively (n = 6 for each). Conclusions: The distribution and function of TRPA1 and CB receptors in prostatic tissue suggest a role for these receptors in mechanoafferent signals, epithelial homeostasis, emission, or inflammation of the human prostate.
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| 3. |
- Hennenberg, Martin, et al.
(författare)
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α1-adrenoceptor activation induces phosphorylation of β2-adrenoceptors in human prostate tissue
- 2011
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Ingår i: BJU International. - 1464-4096 .- 1464-410X. ; 108:6, s. 922-928
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVE:• To test whether β1-adrenoceptor activation leads to phosphorylation of the β2-adrenoceptor in human prostate tissue.PATIENTS AND METHODS:• Prostate tissue from patients undergoing radical prostatectomy was stimulated in vitro with the α1-adrenergic agonist phenylephrine (10 µM).• α2-adrenoceptor phosphorylation at serines 345/346 was studied using Western blot analysis with a phospho-specific antibody.• The role of second messenger kinases was assessed by studying the effects of the protein kinase C (PKC) inhibitor Ro 31-8425 and the protein kinase A (PKA) inhibitor H89 on phenylephrine-induced phosphorylation.• The expression of G protein-coupled receptor kinases (GRKs) 2/3 was analysed using quantitative reverse-transcriptase-polymerase chain reaction (RT-PCR), Western blot analysis and immunohistochemistry.RESULTS:• Stimulation of prostate tissue with phenylephrine resulted in phosphorylation of the β2-adrenoceptor (5, 10 and 20 min after stimulation).• This α1-adrenoceptor-induced phosphorylation of β2-adrenoceptors was resistant to inhibition of PKC and PKA.• Changes in phosphorylation levels were not attributable to changes in receptor levels, as these remained constant during stimulation.• RT-PCR and Western blot analysis showed expression of GRK2/3 in human prostate tissues.• Immunohistochemical staining showed that GRK2/3 expression in human prostate tissue is located to stromal and smooth muscle cells.CONCLUSIONS:• Activation of α1-adrenoceptors causes phosphorylation of β2-adrenoceptors in the human prostate. This may enhance α1-adrenergic contraction and is possibly mediated by GRK2, which is expressed in prostate smooth muscle.• Mutual regulation between different adrenergic receptors might be involved in the therapeutic effects of α1-blockers in patients with benign prostate hyperplasia.
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| 4. |
- Strittmatter, Frank, et al.
(författare)
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Thromboxane A2 induces contraction of human prostate smooth muscle by Rho kinase- and calmodulin-dependent mechanisms
- 2011
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Ingår i: European Journal of Pharmacology. - : Elsevier. - 0014-2999 .- 1879-0712. ; 650:2-3, s. 650-655
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Tidskriftsartikel (refereegranskat)abstract
- Thromboxane A(2) (TXA(2)) induces contraction in different smooth muscle types via its receptor (TXA(2) receptor). However, any motoric role of TXA(2) in prostate smooth muscle tone has not been studied to date. Here, we investigated whether TXA(2) induces contraction of human prostate tissue. After ethical approval, prostate tissue was obtained from 47 patients undergoing radical prostatectomy. Effects of the TXA(2) analogue U46619 ((5Z)-7-[(1R,4S,5S,6R)-6-[(1E,3S)-3-hydroxy-1-octenyl]-2-oxabicyclo[2.2.1]hept-5-yl]-5-heptonic acid) in isolated human prostate strips were studied in organ bath experiments with or without the Rho kinase inhibitor, Y27632 (trans-4-[(1R)-1-aminoethyl]-N-4-pyridinylcyclohexanecarboxamide dihydrochloride), or the calmodulin antagonist W7 (N-(6-aminohexyl)-5-chloro-1-naphtalenesulfonamide hydrochloride). Expression of TXA(2) synthase and TXA(2) receptors were examined by Western blot analysis and immunohistochemistry. Endogenous TXA(2) was quantified by enzyme immunoassay. U46619 induced concentration-dependent contractions of human prostate strips, with a maximum contraction at 3 μM. U46619-induced prostate contraction was significantly inhibited by Y27632 (30 μM) and by W7 (100 μM). TXA(2) synthase and TXA(2) receptors were detected by Western blot analysis. Immunohistochemical stainings showed that expression of TXA(2) synthase in prostate tissue was located to glandular cells, while prostate TXA(2) receptors were located to smooth muscle and glandular cells. The stable TXA(2) metabolite TXB(2) was detected by enzyme immunoassay in the prostate. TXA(2) induces contraction of isolated human prostate tissue by TXA(2) receptor activation. Prostate smooth muscle TXA(2) receptors are coupled to Rho kinase and Ca(2+)-dependent mechanisms. The distribution of TXA(2) synthase and TXA(2) receptors in the human prostate suggests TXA(2)-mediated paracrine epithelial-stromal interactions.
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