Expression of bladder α1-adrenoceptor subtype after relief of partial bladder outlet obstruction in a rat model.

Purpose: Many patients with benign prostatic hyperplasia require treatment for persistent storage symptoms, even when the obstruction is successfully relieved by surgery. Previous studies identified a characteristic increase in α1D-adrenoceptor levels in the bladder in a bladder outlet obstruction (BOO) model. Here, we investigated the expression of α1-adrenoceptor subtypes in the bladder after relief of partial BOO (pBOO) in a rat model. Materials and Methods: A total of 60 female Sprague-Dawley rats were randomly divided into three groups (sham-operated, pBOO, and pBOO relief groups), and the expression of α1-adrenoceptor subtypes in the urothelium and detrusor muscle tissues was examined by western blot. Results: The expression of the α1D-adrenoceptor was significantly higher in the urothelium and detrusor muscle tissue of the pBOO and pBOO relief groups than in the corresponding tissue of the sham-operated group. Additionally, the α1A-adrenoceptor was predominant in the sham-operated group but significantly decreased in the urothelium in the pBOO group. No significant differences were found in α1A-adrenoceptor levels in detrusor muscle or whole bladder. Conclusions: Our results showed that α1D-adrenoceptor levels were consistently increased with pBOO, even after relief, suggesting that the α1D-adrenoceptor might be a cause of persistent storage symptoms after relief of pBOO.

Rapid Reconfiguration of the Functional Connectome after Chemogenetic Locus Coeruleus Activation.

The locus coeruleus (LC) supplies norepinephrine (NE) to the entire forebrain and regulates many fundamental brain functions. Studies in humans have suggested that strong LC activation might shift network connectivity to favor salience processing. To causally test this hypothesis, we use a mouse model to study the effect of LC stimulation on large-scale functional connectivity by combining chemogenetic activation of the LC with resting-state fMRI, an approach we term "chemo-connectomics." We show that LC activation rapidly interrupts ongoing behavior and strongly increases brain-wide connectivity, with the most profound effects in the salience and amygdala networks. Functional connectivity changes strongly correlate with transcript levels of alpha-1 and beta-1 adrenergic receptors across the brain, and functional network connectivity correlates with NE turnover within select brain regions. We propose that these changes in large-scale network connectivity are critical for optimizing neural processing in the context of increased vigilance and threat detection.

Rapid Eye Movement Sleep Deprivation Associated Increase in Na-K ATPase Activity in the Rat Brain is Due to Noradrenaline Induced α1-Adrenoceptor Mediated Increased α-Subunit of the Enzyme.

Rapid eye movement sleep (REMS) modulates Na-K ATPase activity and maintains brain excitability. REMS deprivation (REMSD)-associated increased Na-K ATPase activity is mediated by noradrenaline (NA) acting on α1-adrenoceptor (AR) in the brain. It was shown that NA-induced increased Na-K ATPase activity was due to allosteric modulation as well as increased turnover of the enzyme. Although the former has been studied in detail, our understanding on the latter was lacking, which we have studied. Male Wistar rats were REMS deprived for 4-days by classical flower-pot method; suitable control experiments were conducted. In another set, α1-AR antagonist prazosin (PRZ) was i.p. injected 48 h REMSD onward. At the end of experiments rats were sacrificed by cervical dislocation and brains were removed. Synaptosomes prepared from the brains were used to estimate Na-K ATPase activity as well as protein expressions of different isoforms of the enzyme subunits using western blot. REMSD significantly increased synaptosomal Na-K ATPase activity and that was due to differential increase in the expressions of α1-, α2- and α3-isoforms, but not that of ß1- and ß2-isoforms. PRZ reduced the REMSD-induced increased Na-K ATPase activity and protein expressions. We also observed that the increased Na-K ATPase subunit expression was not due to enhanced mRNA synthesis, which suggests the possibility of post-transcriptional regulation. Thus, the findings suggest that REMSD-associated increased Na-K ATPase activity is due to elevated level of α-subunit of the enzyme and that is induced by NA acting on α1-AR mediated mRNA-stabilization.

ß1-Adrenergic Inhibition Improves Cardiac and Vascular Function in Experimental Septic Shock.

OBJECTIVE: Preliminary experimental data suggest that selective ß1-blockers may improve ex vivo cardiac function in animal sepsis. Currently, the effects of esmolol on in vivo cardiac function and on vascular function are unknown. The present study was designed to examine the effects of the ß1-selective blocker esmolol on myocardial and vascular function in peritonitis-induced septic rats and to explore the inflammatory pathways involved in this process. DESIGN: Randomized animal study. SETTING: University research laboratory. SUBJECTS: Male Wistar rats. INTERVENTIONS: Four hours after cecal ligation and puncture, Wistar rats were randomly allocated to the following groups: control, esmolol, norepinephrine (started at 18 hr after the surgery), and esmolol (started at 4 hr after the surgery) + norepinephrine (started at 18 hr after the surgery). Assessment at 18 hours after surgery was focused on cardiac contractility and vascular ex vivo function. Cardiac and vascular protein expressions of nuclear factor κB and endothelial nitric oxide synthase/Akt/inducible nitric oxide synthase pathways were assessed by Western blotting. MEASUREMENTS AND MAIN RESULTS: When compared with sham-operated animals, cecal ligation and puncture animals developed hypotension, cardiac depression, and vascular hyporesponsiveness to vasopressor treatment. Esmolol infusion increased cardiac contractility and restored mesenteric vasoreactivity. This effect was associated with a decrease in nuclear factor κB activation, an increase in Akt and endothelial nitric oxide synthase phosphorylation, and a decrease in inducible nitric oxide synthase expression both at the cardiac and vessel level. Esmolol infusion was also associated with an up-regulation in α1-vascular adrenoreceptors. CONCLUSION: Adjunction of selective ß1-blockade to standard septic shock management enhances intrinsic cardiac contractility and vascular responsiveness to catecholamines. These protective cardiovascular effects are likely predominantly attributed to the anti-inflammatory effect of esmolol.

Dopamine D1-like receptors regulate the α1A-adrenergic receptor in human renal proximal tubule cells and D1-like dopamine receptor knockout mice.

The homeostatic control of blood pressure hinges upon the delicate balance between prohypertensinogenic and antihypertensinogenic systems. D1-like dopamine receptors [dopamine D1 and D5 receptors (D1Rs and D5Rs, respectively)] and the α1A-adrenergic receptor (α1A-AR) are expressed in the renal proximal tubule and engender opposing effects on Na(+) transport, i.e., natriuresis (via D1Rs and D5Rs) or antinatriuresis (via α1A-ARs). We tested the hypothesis that the D1R/D5R regulates the α1A-AR. D1-like dopamine receptors coimmunoprecipitated, colocalized, and cofractionated with α1A-ARs in lipid rafts in immortalized human renal proximal tubule cells. Long-term treatment with the D1R/D5R agonist fenoldopam resulted in decreased D1R and D5R expression but increased α1A-AR abundance in the plasma membrane. Short-term fenoldopam treatment stimulated the translocation of Na(+)-K(+)-ATPase from the plasma membrane to the cytosol that was partially reversed by an α1A-AR agonist, which by itself induced Na(+)-K(+)-ATPase translocation from the cytosol to the plasma membrane. The α1A-AR-specific agonist A610603 also minimized the ability of fenoldopam to inhibit Na(+)-K(+)-ATPase activity. To determine the interaction among D1Rs, D5Rs, and α1A-ARs in vivo, we used phenylephrine and A610603 to decrease Na(+) excretion in several D1-like dopamine receptor knockout mouse strains. Phenylephrine and A61603 treatment resulted in a partial reduction of urinary Na(+) excretion in wild-type mice and its abolition in D1R knockout, D5R knockout, and D1R-D5R double-knockout mice. Our results demonstrate the ability of the D1-like dopamine receptors to regulate the expression and activity of α1A-AR. Elucidating the intricacies of the interaction among these receptors is crucial for a better understanding of the crosstalk between anti- and pro-hypertensive systems.

Interleukin 1ß attenuates vascular α1 adrenergic receptors expression following lipopolysaccharide-induced endotoxemia in rabbits: involvement of JAK2-STAT3 pathway.

BACKGROUND: Studies have shown that interleukin 1ß (IL-1ß) participates in the down-regulation of vascular reactivity via both nitric oxide-dependent and nitric oxide-independent mechanisms during shock. However, the precise mechanisms of nitric oxide-independent pathway remain to be established. METHODS: The effect of IL-1ß on the expression of α1 adrenergic receptors (α1AR) and the relationship with Janus kinase 2-signal transducer and activator of transcription 3 (JAK2-STAT3) pathway were observed using a rabbit model of lipopolysaccharide (LPS)-induced endotoxemia and superior mesenteric arteries (SMAs) in vivo and in vitro, respectively. RESULTS: The vascular reactivity of SMAs to α1AR agonist (phenylephrine) displayed a biphasic change after LPS (significantly increased at 0.5 hour following LPS and then markedly decreased after 2 hours), the α1A, α1B and α1DAR messenger RNA (mRNA) and protein expression seemed a time-dependent decrease following LPS administration, α1A and α1DAR decreased more obviously than α1BAR. IL-1ra (4 µg/mL) partly reversed LPS-induced the decrease of vascular reactivity and down-regulation of α1AR expression. In vitro incubation with IL-1ß (12.5-50 ng/mL) significantly decreased the vascular reactivity of SMA to phenylephrine and the expression of α1AR mRNA and protein and elevated the DNA binding ability of STAT3. AG490 (10 µmol/L), an inhibitor of JAK2, partly reversed the IL-1ß-induced down-regulation of vascular reactivity and α1AR mRNA and protein expression and suppressed the DNA binding ability of STAT3. CONCLUSION: IL-1ß participates in the regulation of vascular hyporeactivity following endotoxemia in rabbit. The mechanism is related to the down-regulation of α1AR expression through activating the JAK2-STAT3 pathway.

Upregulation of α1-adrenoceptors on cutaneous nerve fibres after partial sciatic nerve ligation and in complex regional pain syndrome type II.

After peripheral nerve injury, nociceptive afferents acquire an abnormal excitability to adrenergic agents, possibly due to an enhanced expression of α1-adrenoceptors (α1-ARs) on these nerve fibres. To investigate this in the present study, changes in α1-AR expression on nerve fibres in the skin and sciatic nerve trunk were assessed using immunohistochemistry in an animal model of neuropathic pain involving partial ligation of the sciatic nerve. In addition, α1-AR expression on nerve fibres was examined in painful and unaffected skin of patients who developed complex regional pain syndrome (CRPS) after a peripheral nerve injury (CRPS type II). Four days after partial ligation of the sciatic nerve, α1-AR expression was greater on dermal nerve fibres that survived the injury than on dermal nerve fibres after sham surgery. This heightened α1-AR expression was observed on nonpeptidergic nociceptive afferents in the injured sciatic nerve, dermal nerve bundles, and the papillary dermis. Heightened expression of α1-AR in dermal nerve bundles after peripheral nerve injury also colocalized with neurofilament 200, a marker of myelinated nerve fibres. In each patient examined, α1-AR expression was greater on nerve fibres in skin affected by CRPS than in unaffected skin from the same patient or from pain-free controls. Together, these findings provide compelling evidence for an upregulation of α1-ARs on cutaneous nociceptive afferents after peripheral nerve injury. Activation of these receptors by circulating or locally secreted catecholamines might contribute to chronic pain in CRPS type II.

Pannexin 1 in the regulation of vascular tone.

Pannexins are a recently discovered protein family with the isoform Panx1 ubiquitously expressed and therefore extensively studied. Panx1 proteins form membrane channels known to release purines such as ATP. Because ATP and, more generally, purinergic signaling plays an important role in the vasculature, it became evident that Panx1 could have a key role in vascular functions. This article reviews recent findings on the pivotal role of Panx1 in smooth muscle cells in the contraction of arteries as well as recent insights into Panx1 channel regulation.

Intravesical epinephrine preserves uroplakin II expression in urinary bladder from cyclophosphamide-induced rat cystitis.

We investigated the attenuated effect of intravesical epinephrine (EPI) on uroplakin II (UPII) expression in cyclophosphamide (CYP)-induced rat cystitis. Sixty-eight Sprague-Dawley female rats were divided into one negative control group (GI) and five intraperitoneally CYP (150 mg CYP/kg)-injected groups (GII-VI) consisting of a positive control group (GII), three groups (GIII-V) with retaining intravesically instillated ameliorating agents for 90 min by urethral ligation until sacrifice, and one group (GVI) with freely voiding after intravesical EPI instillation. The retention groups were further classified into null-treated- (GIII), EPI- (GIV), and vehicle group (GV). All rats were euthanized 24 h after CYP injection. The UPII and α1-adrenergic receptors (AR) levels were measured with real-time polymerase chain reaction (RT-PCR) method and the morphological changes were also evaluated. CYP induced severe cystitis and decreased vesical UPII mRNA level. The EPI-treated groups had showed attenuation effects against submucosal edema and hemorrhage, and preserved UPII expression. Concurrently, intravesical EPI resulted in a significant preservation of both subtypes of α1A- and α1B AR expressions, which was well correlated with the hemostatic pattern in the samples. The obstructed and null-treated group (GIII) revealed severe cystitis and maximally decreased UPII levels, and the diluting effect of vehicle (GV) on CYP toxicity was insignificant on UPII preservation. The UPII level of RT-PCR was well correlated with the UPII immunohistological expression and their morphological changes. Intravesical instillation of EPI preserves UPII expression and attenuates the toxic responses in the bladder in CYP-induced rat cystitis.

[The increase in the proportion of nervous animals bred for catatonia: the participation of central adrenoreceptors in catatonic reactions].

Using a large amount of breeding material, the idea of D. K. Belyaev on the role of selection in the appearance of new behavioral and neuronal forms was confirmed. Experiments were performed using rats of the GC (genetics + catatonia) strain, which are prone to passive defensive reactions of cataleptic freezing. At the current breeding stage, elevation of the proportion of so-called nervous animals was demonstrated, both with respect to the expression of such reactions and their frequency. At this breeding stage, in the brains of GC rats, the mRNA levels of alpha1A- and alpha2A-adrenoreceptor genes were determined. A decrease of alpha1A-adrenoreceptor gene expression in the midbrain and medulla oblongata, along with elevation of alpha2A-adrenoreceptor gene expression in the frontal cortex was observed. It was suggested that changes in the expression of alpha-adrenoreceptor genes could be caused by an increase in the proportion of nervous animals and could contribute to the akinetic behavioral component in GC rats.

α1-adrenergic receptors positively regulate Toll-like receptor cytokine production from human monocytes and macrophages.

Catecholamines released from the sympathetic nervous system in response to stress or injury affect expression of inflammatory cytokines generated by immune cells. α(1)-Adrenergic receptors (ARs) are expressed on innate immune cell populations, but their subtype expression patterns and signaling characteristics are not well characterized. Primary human monocytes, a human monocytic cell line, and monocyte-derived macrophage cells were used to measure expression of the proinflammatory mediator interleukin (IL)-1ß responding to lipopolysaccharide (LPS) in the presence or absence of α(1)-AR activation. Based on our previous findings, we hypothesized that α(1)-AR stimulation on innate immune cells positively regulates LPS-initiated IL-1ß production. IL-1ß production in response to LPS was synergistically higher for both monocytes and macrophages in the presence of the selective α(1)-AR agonist (R)-(-)-phenylephrine hydrochloride (PE). This synergistic IL-1ß response could be blocked with a selective α(1)-AR antagonist as well as inhibitors of protein kinase C (PKC). Radioligand binding studies characterized a homogenous α(1B)-AR subtype population on monocytes, which changed to a heterogeneous receptor subtype expression pattern when differentiated to macrophages. Furthermore, increased p38 mitogen-activated protein kinase (MAPK) activation was observed only with concurrent PE and LPS stimulation, peaking after 120 and 30 min in monocytes and macrophages, respectively. Blocking the PKC/p38 MAPK signaling pathway in both innate immune cell types inhibited the synergistic IL-1ß increase observed with concurrent PE and LPS treatments. This study characterizes α(1)-AR subtype expression on both human monocyte and macrophage cells and illustrates a mechanism by which increased IL-1ß production can be modulated by α(1)-AR input.

Immunoexpression of adrenergic receptors in detrusor from patients with prune belly syndrome: a digital quantification.

INTRODUCTION: Prune belly syndrome (PBS) presents with large-capacity bladders, high compliance and post-void residual volumes. Operative and conservative treatments are controversial. When histologically compared to normal bladder, bladder outlet obstruction results in an up- or down-regulation of adrenoceptors. Our goal was to study the immunoexpression of adrenoceptors in detrusor from patients with PBS. MATERIALS AND METHODS: Bladder domes from PBS patients (n=14) were studied (PBG). For normal controls, bladder specimens were obtained at adult surgery (n=13) (CG1) and at child autopsy (n=5) (CG2). Staining was performed using antibodies to alpha1a, alpha1b, alpha1d and beta3 adrenoceptors. Five to 10 images were captured on an optic microscope with a digital camera and analysed with Photoshop. The immunocyhistochemical index with arbitrary units was calculated and compared. RESULTS: Mean age was 1.28, 64 and 1.41 years for PBG, CG1 and CG2, respectively. The immunohistochemical index with arbitrary units of alpha1a receptors was 0.06 in PBG, 0.16 in CG1 and 0.14 in CG2 (p=0.008); of alpha1b 0.06, 0.06 and 0.07 (p=0.781); and of alpha1d 0.04, 0.04 and 0.05 (p=0.618). Regarding beta3 the respective values were 0.07, 0.14 and 0.10 (p=0.378). CONCLUSION: Our results show a decrease in alpha1a-adrenoceptor immunostaining intensity in detrusor from children with PBS. Further in vitro studies are needed to determine whether these observations are physiologically significant.

Effects of lactational exposure to benzo[alpha]pyrene (B[alpha]P) on postnatal neurodevelopment, neuronal receptor gene expression and behaviour in mice.

The harmful effects of exposure to benzo[alpha]pyrene (B[alpha]P), which is a neurotoxic pollutant, on mammalian neurodevelopment and/or behaviour as yet remain widely unclear. In the present investigation, we evaluated the impact of the lactational exposure to B[alpha]P on postnatal development of pups and behaviour of young mice. The neurobiological effects of B[alpha]P during lactation were also evaluated on pups' brain. Here, we found that lactational exposure to B[alpha]P at 2 and 20mg/kg affects the neuromaturation of pups by significantly decreasing their reflex as highlighted in surface righting reflex and negative geotaxis tests. However, we noted a significant increase in muscular strength of lactationally B[alpha]P mg/kg-exposed pups, which was probably due to the impact of the exposure to this toxic compound on body weight gain. At the pup stage, lactational exposure to B[alpha]P also provoked a neurobiological change, which was assessed by determination of neuronal receptor gene expression. Indeed, a significant reduction in gene expression of 5HT(1A) receptors in pups exposed to B[alpha]P through lactation was found in comparison to controls. Additionally, attenuation in the expression of MOR(1) mRNA was observed, but statistically significant only in animals receiving the higher dose. Neither the expression levels of ADRA(1D) nor GABA(A) mRNA were altered. Interestingly, the harmful effects of lactational exposure to B[alpha]P on behaviour and cognitive function were still found despite a long post-weaning period. Young mice whose mothers were exposed to B[alpha]P displayed a disinhibition behaviour towards the aversive spaces of the elevated plus maze. Furthermore, a significant increase of spontaneous alternation in the Y-maze was observed, but only in young mice whose mothers were orally exposed to the lower dose of B[alpha]P. Our results suggest a close link between the neurobiological change highlighted in pups' brain and the different behavioural disturbances observed during postnatal development period until young adult stage.

Association of overactive bladder and stress urinary incontinence in rats with pudendal nerve ligation injury.

Approximately one-third of patients with stress urinary incontinence (SUI) also suffer from urgency incontinence, which is one of the major symptoms of overactive bladder (OAB) syndrome. Pudendal nerve injury has been recognized as a possible cause for both SUI and OAB. Therefore, we investigated the effects of pudendal nerve ligation (PNL) on bladder function and urinary continence in female Sprague-Dawley rats. Conscious cystometry with or without capsaicin pretreatment (125 mg/kg sc), leak point pressures (LPPs), contractile responses of bladder muscle strips to carbachol or phenylephrine, and levels of nerve growth factor (NGF) protein and mRNA in the bladder were compared in sham and PNL rats 4 wk after the injury. Urinary frequency detected by a reduction in intercontraction intervals and voided volume was observed in PNL rats compared with sham rats, but it was not seen in PNL rats with capsaicin pretreatment that desensitizes C-fiber-afferent pathways. LPPs in PNL rats were significantly decreased compared with sham rats. The contractile responses of detrusor muscle strips to phenylephrine, but not to carbachol, were significantly increased in PNL rats. The levels of NGF protein and mRNA in the bladder of PNL rats were significantly increased compared with sham rats. These results suggest that pudendal nerve neuropathy induced by PNL may be one of the potential risk factors for OAB, as well as SUI. Somato-visceral cross sensitization between somatic (pudendal) and visceral (bladder) sensory pathways that increases NGF expression and alpha(1)-adrenoceptor-mediated contractility in the bladder may be involved in this pathophysiological mechanism.

Expression of alpha1-adrenoceptor subtype mRNA as a predictor of the efficacy of subtype selective alpha1-adrenoceptor antagonists in the management of benign prostatic hyperplasia.

PURPOSE: We examined the correlation between the expression of alpha1-adrenoceptor subtype mRNA in the prostate and the clinical efficacy of subtype selective alpha1-adrenoceptor antagonists. We discuss the possibility of individualizing drug therapy in patients with benign prostatic hyperplasia. MATERIALS AND METHODS: A total of 33 patients randomized to the tamsulosin group and 28 randomized to the naftopidil group were enrolled in this study. Each group of patients was administered 0.2 mg tamsulosin hydrochloride or 50 mg naftopidil daily for 12 weeks. Four prostate needle biopsy specimens were obtained from the transition zone to examine the expression of alpha-adrenoceptor subtypes. Specimens were stored at -80 C until used for TaqMan quantitative reverse transcriptase-polymerase chain reaction, which was performed after 12 weeks of treatment. RESULTS: Based on the results of quantitative reverse transcriptase-polymerase chain reaction the tamsulosin and naftopidil groups were grouped into alpha1a-adrenoceptor dominant (22 and 12 patients) and alpha1d-adrenoceptor dominant (11 and 16, respectively) subgroups. The efficacy of tamsulosin hydrochloride and naftopidil differed depending on the dominant expression of the alpha1-adrenoceptor subtype in the prostate. Tamsulosin hydrochloride was more effective in patients with dominant expression of the alpha1a-adrenoceptor subtype, whereas naftopidil was more effective in those with dominant expression of the alpha1d-adrenoceptor subtype. CONCLUSIONS: The expression level of alpha1-adrenoceptor subtype mRNA in the prostate could be a predictor of the efficacy of subtype selective alpha1-adrenoceptor antagonists in patients with benign prostatic hyperplasia. This result implies that genetic differences are responsible for the diverse responses to these drugs.

Change of expression levels of alpha1-adrenoceptor subtypes by administration of alpha1d-adrenoceptor-subtype-selective antagonist naftopidil in benign prostate hyperplasia patients.

BACKGROUND: We examined whether the change of alpha(1)-adrenoceptor (alpha(1)-AR) subtype expression levels in the prostate occurred by administration of the alpha(1d)-AR-subtype-selective antagonist naftopidil to benign prostate hyperplasia (BPH) patients, and discussed the possible alternation of its effectiveness by the chronic administration of alpha(1)-AR antagonists. METHODS: Fifteen patients with untreated BPH aged 58-76 (mean age, 68.2 +/- 7.4 years) underwent prostate biopsy from the transition zone before and after 50 mg naftopidil administration daily for 12 weeks. Taqman quantitative reverse transcription polymerase chain reaction was performed using these biopsy specimens to estimate the expression level of each alpha(1)-AR subtype. Comparison was made of the expression level of alpha(1)-AR subtypes before and after naftopidil administration. We also examined the correlation between the change of alpha(1)-AR subtype expression levels and the short-term efficacy of naftopidil. RESULTS: Naftopidil administration for 12 weeks down-regulated the expression of alpha(1a)-AR and alpha(1b)-AR mRNA and up-regulated the expression of alpha(1d)-AR mRNA without a change in the total alpha(1)-AR mRNA expression level. There was no correlation between the change of alpha(1)-AR subtype expression levels and the short-term efficacy of naftopidil for BPH patients. CONCLUSION: The change of alpha(1d)-AR expression level may be regarded as a compensatory adaptation to chronic alpha(1d)-AR antagonist naftopidil administration. This may mean that long-term use of the same alpha(1)-AR antagonist for BPH patients induces therapeutic tolerance.

Epigenetic regulation of human alpha1d-adrenergic receptor gene expression: a role for DNA methylation in Sp1-dependent regulation.

A growing body of evidence implicates alpha1-adrenergic receptors (alpha1ARs) as potent regulators of growth pathways. The three alpha1AR subtypes (alpha1aAR, alpha1bAR, alpha1dAR) display highly restricted tissue expression that undergoes subtype switching with many pathological stimuli, the mechanistic basis of which remains unknown. To gain insight into transcriptional pathways governing cell-specific regulation of the human alpha1dAR subtype, we cloned and characterized the alpha1dAR promoter region in two human cellular models that display disparate levels of endogenous alpha1dAR expression (SK-N-MC and DU145). Results reveal that alpha1dAR basal expression is regulated by Sp1-dependent binding of two promoter-proximal GC boxes, the mutation of which attenuates alpha1dAR promoter activity 10-fold. Mechanistically, chromatin immunoprecipitation data demonstrate that Sp1 binding correlates with expression of the endogenous gene in vivo, correlating highly with alpha1dAR promoter methylation-dependent silencing of both episomally expressed reporter constructs and the endogenous gene. Further, analysis of methylation status of proximal GC boxes using sodium bisulfite sequencing reveals differential methylation of proximal GC boxes in the two cell lines examined. Together, the data support a mechanism of methylation-dependent disruption of Sp1 binding in a cell-specific manner resulting in repression of basal alpha1dAR expression.

Quantification of alpha1-adrenoceptor subtypes by real-time RT-PCR and correlation with age and prostate volume in benign prostatic hyperplasia patients.

BACKGROUND: We used a real-time reverse transcriptase polymerase chain reaction (RT-PCR) method for quantification of each alpha(1)-adrenoceptor (alpha(1)-AR) subtype expression level, and examined whether age and prostate volume influence human prostate alpha(1)-AR subtype expression. METHODS: Enrolled in our study were 75 men with lower urinary tract symptoms (LUTS) secondary to untreated benign prostatic hyperplasia (BPH). Real-time RT-PCR was performed using prostate biopsy specimens to quantify the expression level of each alpha(1)-AR subtype. RESULTS: The median expression level (interquartile range) was 1.24 (0.66-2.32), 0.16 (0.10-0.33), and 1.11 (0.75-2.27) x 1,000 copies/beta-actin for alpha(1a)-, alpha(1b)-, and alpha(1d)-AR mRNA, respectively. The expression levels differed with the individual. The expression levels of alpha(1a)-AR, alpha(1d)-AR, and total alpha(1)-AR mRNA showed a significant positive correlation with patient age, but did not correlate with prostate volume. CONCLUSION: The difference in the expression of the alpha(1)-AR subtype with the patient may be the cause of the difference in the effectiveness of several subtype-selective alpha(1)-AR antagonists from patient to patient. The increase of alpha(1)-AR mRNA expression level with age could be an important factor in the pathogenesis of clinically significant BPH.

Induction of beta3-adrenergic receptor functional expression following chronic stimulation with noradrenaline in neonatal rat cardiomyocytes.

This study aimed to characterize beta(3)-adrenergic receptors (ARs) in rat neonatal cardiomyocytes using the noradrenaline (NOR) properties to modulate the expression and function of the three beta-ARs. We assessed the effect of NOR (physiological nonselective agonist), isoprenaline (ISO, beta-nonselective agonist), dobutamine (DOB, beta(1)-selective agonist), and procaterol (PROC, beta(2)-selective agonist) on cAMP accumulation using cardiomyocytes untreated or treated with 100 microM NOR for 24 h. The inhibition of forskolin-stimulated cAMP accumulation was determined using NOR, isoprenaline, and the beta(3)-selective agonists 4-[2-[(2-(3-chlorophenyl)-2-hydroxyethyl)amino]propyl]phenoxyacetic acid (BRL 37344) and 5-[-2-([-2-(3-chlorophenyl)-2-hydroxyethyl]amino)propyl]-1,3-benzodioxole-2,2-dicarboxylate (CL 316243). The experiments were performed in the absence or presence of propranolol or 2-hydroxy-5-[2-[[2-hydroxy-3-[4-[1-methyl-4-(trifluoromethyl)-1H-imidazol-2-yl]phenoxy]propyl]amino]ethoxy]-benzamide methanesulfonate (CGP 20712A) and/or 1-[2,3-(dihydro-7-methyl-1H-inden-4-yl)oxy]-3-[(1-methylethyl)amino]-2-butanol hydrochloride (ICI 118551) to inhibit beta(1)- and beta(2)-AR stimulation and 1-(2-ethylphenoxy)-3-[[1S)-1,2,3,4-tetrahydro-1-naphthalenyl]amino-(2S)-2-propanol hydrochloride (SR 59230A) (beta(3)-selective antagonist). In addition, the level of the three subtypes was determined by reverse transcription polymerase chain reaction and Western blotting. NOR pretreatment decreased the activation of cAMP induced by NOR, isoprenaline, and DOB, whereas PROC response was abolished. The inhibition of NOR response by CGP 20712A or ICI 118551 demonstrated that beta(1)- and beta(2)-ARs are down-regulated and that beta(2)-AR functional activity was also abolished in cardiomyocytes exposed to chronic stimulation. beta(3)-AR function was observed with NOR and ISO when beta(1)-/beta(2)-ARs were blocked and with both beta(3)-selective agonists in NOR-treated cells only. This response was completely inhibited by SR 59230A and involved G(i) protein. Furthermore, the results from functional studies agree well with those from expression experiments. In conclusion, these data provide strong evidence that beta(3)-ARs are functionally up-regulated and coupled to G(i) protein in rat neonatal cardiomyocytes following chronic exposure to NOR when beta(1)- and beta(2)-ARs are down-regulated.

Cardiac remodeling after long-term stimulation by antibodies against the alpha1-adrenergic receptor in rats.

Although autoantibodies against the alpha1-adrenergic receptor which had been found in hypertensive patients had agonist-like activity as phenylephrine, the effects of these antibodies on cardiac remodeling have not been known. In this paper, the models with agonist-like activity of antibodies to alpha1-adrenergic receptor were made by immunized Wistar rats using synthesized peptides of alpha1A-adrenergic receptor and raised for 1 year, and the excited antibodies against the alpha1-adrenergic receptor which could elevate the free Ca2+ in isolated adult rat cardiomyocytes had been existed throughout the experiments after immunization. In immunized rats, despite that systolic blood pressure (SBP) had no difference with normal control, the hypertrophy of heart and cardiomyocytes was observed, the collagen deposition in heart interstitium increased, and c-jun expression and matrix metalloproteinase (MMP)-2 mRNA expression and activity in heart had increased. The results suggested that antibodies against the alpha1-adrenergic receptor could induce cardiac remodeling and maybe play a particular role in hypertension.