Terazosin Modifies the Content of Glycosaminoglycans and the Activity of Matrix Metalloproteinase 2 in the Rat Ventral Prostate

RNA Contaminates Glycosaminoglycans Extracted from Cells and Tissues

Glycosaminoglycans (GAGs) are linear negatively charged polysaccharides and important components of extracellular matrices and cell surface glycan layers such as the endothelial glycocalyx. The GAG family includes sulfated heparin, heparan sulfate (HS), dermatan sulfate (DS), chondroitin sulfate (CS), keratan sulfate, and non-sulfated hyaluronan. Because relative expression of GAGs is dependent on cell-type and niche, isolating GAGs from cell cultures and tissues may provide insight into cell- and tissue-specific GAG structure and functions. In our objective to obtain structural information about the GAGs expressed on a specialized mouse glomerular endothelial cell culture (mGEnC-1) we adapted a recently published GAG isolation protocol, based on cell lysis, proteinase K and DNase I digestion. Analysis of the GAGs contributing to the mGEnC-1 glycocalyx indicated a large HS and a minor CS content on barium acetate gel. However, isolated GAGs appeared resistant to enzymatic digestion by heparinases. We found that these GAG extracts were heavily contaminated with RNA, which co-migrated with HS in barium acetate gel electrophoresis and interfered with 1,9-dimethylmethylene blue (DMMB) assays, resulting in an overestimation of GAG yields. We hypothesized that RNA may be contaminating GAG extracts from other cell cultures and possibly tissue, and therefore investigated potential RNA contaminations in GAG extracts from two additional cell lines, human umbilical vein endothelial cells and retinal pigmental epithelial cells, and mouse kidney, liver, spleen and heart tissue. GAG extracts from all examined cell lines and tissues contained varying amounts of contaminating RNA, which interfered with GAG quantification using DMMB assays and characterization of GAGs by barium acetate gel electrophoresis. We therefore recommend routinely evaluating the RNA content of GAG extracts and propose a robust protocol for GAG isolation that includes an RNA digestion step.

Terazosin treatment induces caspase-3 expression in the rat ventral prostate

BACKGROUND

Quinazoline-based alpha1-adrenergic receptor antagonists may not act solely on smooth muscle contractility. We evaluated the in vivo effect of terazosin on the expression of caspase-3 in the rat ventral prostate.

METHODS

Fifteen Wistar rats were treated with terazosin (1.2 mg/kg body weight, given orally every second day) for 120 days. Another 15 control animals received the same amount of distilled water. The expression of caspase-3 was assessed immunohistochemically in formalin-fixed, paraffin-embedded tissue sections.

RESULTS

Terazosin treatment did not affect prostate weight and histomorphology. In controls caspase-3 was expressed weakly and sporadically. In contrast, strong and weak expression was evident in 67% and 33% of the terazosin-treated specimens, respectively.

CONCLUSIONS

These findings implicate the induction of caspase-3 expression by terazosin as a potential molecular mechanism of its apoptotic action on prostate cells.

The relationship between the MMP system, adrenoceptors and phosphoprotein phosphatases

The MMPs and their inhibitors [tissue inhibitor of MMPs (TIMPs)] form the mainstay of extracellular matrix homeostasis. They are expressed in response to numerous stimuli including cytokines and GPCR activation. This review highlights the importance of adrenoceptors and phosphoprotein phosphatases (PPP) in regulating MMPs in the cardiovascular system, which may help explain some of the beneficial effects of targeting the adrenoceptor system in tissue remodelling and will establish emerging crosstalk between these three systems. Although α- and β-adrenoceptor activation increases MMP but decreases TIMP expression, MMPs are implicated in the growth stimulatory effects of adrenoceptor activation through transactivation of epidermal growth factor receptor. Furthermore, they have recently been found to catalyse the proteolysis of β-adrenoceptors and modulate vascular tone. While the mechanisms underpinning these effects are not well defined, reversible protein phosphorylation by kinases and phosphatases may be key. In particular, PPP (Ser/Thr phosphatases) are not only critical in resensitization and internalization of adrenoceptors but also modulate MMP expression. The interrelationship is complex as isoprenaline (ISO) inhibits okadaic acid [phosphoprotein phosphatase type 1/phosphoprotein phosphatase type 2A (PP2A) inhibitor]-mediated MMP expression. While this may be simply due to its ability to transiently increase PP2A activity, there is evidence for MMP-9 that ISO prevents okadaic acid-mediated expression of MMP-9 through a β-arrestin, NF-κB-dependent pathway, which is abolished by knock-down of PP2A. It is essential that crosstalk between MMPs, adrenoceptors and PPP are investigated further as it will provide important insight into how adrenoceptors modulate cardiovascular remodelling, and may identify new targets for pharmacological manipulation of the MMP system.

Doxazosin treatment alters stromal cell behavior and increases elastic system fibers deposition in rat prostate

Doxazosin (DOX), an α-adrenoceptor antagonist, induces the relaxation of smooth muscle cell tonus and reduces the clinical symptoms of benign prostatic hyperplasia (BPH). However, the effects of DOX in the prostate stromal microenvironment are not fully known. In a previous study, we showed that DOX treatment for 30 days increased deposition of collagen fibers in the three rat prostatic lobes. Herein, we investigated the effects of DOX on stromal cell ultrastructure and elastic fiber deposition. Adult Wistar rats were treated with DOX (25 mg/kg/day); and the ventral, dorsal, and anterior prostates were excised at 30 days of treatment. The prostatic lobes were submitted to histochemical and stereological-morphometric analyze and transmission electron microscopy (TEM). Histochemical staining plus stereological analysis of the elastic fiber system showed that DOX-treated prostatic lobes presented more elaunin and elastic fibers than controls, mainly in the ventral lobe. Ultrastructural analysis showed that fibroblasts and smooth muscle cells from DOX-treated prostates presented active synthetic phenotypes, evidenced by enlarged rough endoplasmic reticulum and Golgi apparatus cisterns, and confirmed the observation of thickened elaunin fibers. Our findings suggest that, under α-adrenergic blockade by DOX, the fibroblasts become more active and smooth muscle cells shift from a predominantly contractile to a more synthetic phenotype. The deposition of collagen and elastic system fibers in the prostatic stroma may counterbalance the absence of smooth muscle tone during α-blockers treatment.

Matrix metalloproteinase (MMP)-2 and MMP-9 activity and localization during ventral prostate atrophy and regrowth

Matrix metalloproteinses (MMPs) are enzymes involved in prostatic development, growth, disease-induced tissue remodelling and secretory fluid. Although the prostate function depends upon androgen regulation, the relationship between MMPs and androgen has not been well established. Here, we evaluated MMP-2 and MMP-9 gelatinolytic activity in association with tissue localization during ventral prostate atrophy and regrowth induced by testosterone replacement (TR). Adult male Wistar rats were divided into three experimental groups: control, castrated (CS) and TR 21 days after castration. Ventral prostate (VP) was excised at 3, 5, 7 and 21 days after castration in CS group, and at 3, 5, 7 and 10 days after TR (4 mg/kg/day) in TR group. The VP was dissected, weighed and processed for histology, immunohistochemistry, ultrastructure and zymography analyses. Castration elicited the typical parenchymal atrophy and stromal condensation. TR induced intense epithelial growth towards the stromal space to restore the prostate histoarchitecture. MMP-2 and MMP-9 immunostaining presented intense reaction in CS and TR groups, mainly in the epithelial and endothelial cells. After TR, a strong immunoreaction for MMP-2 was observed in the activated stromal fibroblasts. Zymography showed that MMP-2 and MMP-9 activity, mainly the active form, increased after castration. In contrast, TR induced an additional increase in MMP-2 activity, but not in MMP-9. In conclusion, the overall behaviour of MMP-2 and MMP-9 within the prostate under androgen handling is highly complex, as each glandular compartment and cell type is affected differently by the androgenic status. Prostate regrowth appears to involve a more effective participation of MMP-2 in both epithelial and stromal compartments, while MMP-9 plays a major role in the late prostate atrophy and early regrowth.

Combined use of melatonin and terazosin restores bladder contractility in rabbits with partial outlet obstruction

OBJECTIVES

To investigate the effects of terazosin and melatonin on isolated rabbit bladder strips after partial bladder outlet obstruction and determine responses to agonist-induced contractility and changes in oxidant-antioxidant system.

METHODS

We created partial bladder outlet obstruction in 5 groups of rabbits, each containing 8. Rabbits with sham operation (group 1) received no drug treatment. Similarly, animals in group 2 underwent partial bladder outlet obstruction and received no drug treatment. Rabbits in groups 3 were administered 5 mg/day oral terazosin, and rabbits in group 4 received 10 mg/kg/day melatonin intraperitoneally. Animals in group 5 received both terazosin and melatonin. We removed their bladders and performed histopathological and biochemical measurements. We assessed tissue malondialdehyde and antioxidant enzyme activity levels and recorded in vitro contractility response to KCl in isolated organ baths.

RESULTS

The thickness of muscularis propria was significantly increased in group 2 compared with all other groups. KCl-evoked contractions after partial outlet obstruction were significantly impaired in group 3 and 4 animals receiving terazosin and melatonin, respectively. However, combined use of melatonin and terazosin in group 5 showed contractility responses similar to sham-operated animals (P <0.05). Melatonin administration to groups 4 and 5 showed decreased levels of lipid peroxidation. Similarly, animals receiving melatonin and melatonin plus terazosin showed statistically significant increase in antioxidant enzyme activities.

CONCLUSIONS

In the present study, we showed that oxidative stress induced by partial bladder outlet obstruction can be successfully antagonized by the potent antioxidant melatonin, and its combined use with an alpha-antagonist such as terazosin may restore in vitro contractility.