Cell Surface Platelet Tissue Factor Expression: Regulation by P2Y12 and Link to Residual Platelet Reactivity

BACKGROUND

ADP-induced platelet activation leads to cell surface expression of several proteins, including TF (tissue factor). The role of ADP receptors in platelet TF modulation is still unknown. We aimed to assess the (1) involvement of P2Y1 and P2Y12 receptors in ADP-induced TF exposure; (2) modulation of TFpos-platelets in anti-P2Y12-treated patients with coronary artery disease. Based on the obtained results, we revisited the intracellular localization of TF in platelets.

METHODS

The effects of P2Y1 or P2Y12 antagonists on ADP-induced TF expression and activity were analyzed in vitro by flow cytometry and thrombin generation assay in blood from healthy subjects, P2Y12-/-, and patients with gray platelet syndrome. Ex vivo, P2Y12 inhibition of TF expression by clopidogrel/prasugrel/ticagrelor, assessed by VASP (vasodilator-stimulated phosphoprotein) platelet reactivity index, was investigated in coronary artery disease (n=238). Inhibition of open canalicular system externalization and electron microscopy (TEM) were used for TF localization.

RESULTS

In blood from healthy subjects, stimulated in vitro by ADP, the percentage of TFpos-platelets (17.3±5.5%) was significantly reduced in a concentration-dependent manner by P2Y12 inhibition only (-81.7±9.5% with 100 nM AR-C69931MX). In coronary artery disease, inhibition of P2Y12 is paralleled by reduction of ADP-induced platelet TF expression (VASP platelet reactivity index: 17.9±11%, 20.9±11.3%, 40.3±13%; TFpos-platelets: 10.5±4.8%, 9.8±5.9%, 13.6±6.3%, in prasugrel/ticagrelor/clopidogrel-treated patients, respectively). Despite this, 15% of clopidogrel good responders had a level of TFpos-platelets similar to the poor-responder group. Indeed, a stronger P2Y12 inhibition (130-fold) is required to inhibit TF than VASP. Thus, a VASP platelet reactivity index <20% (as in prasugrel/ticagrelor-treated patients) identifies patients with TFpos-platelets <20% (92% sensitivity). Finally, colchicine impaired in vitro ADP-induced TF expression but not α-granule release, suggesting that TF is open canalicular system stored as confirmed by TEM and platelet analysis of patients with gray platelet syndrome.

CONCLUSIONS

Data show that TF expression is regulated by P2Y12 and not P2Y1; P2Y12 antagonists downregulate the percentage of TFpos-platelets. In clopidogrel good-responder patients, assessment of TFpos-platelets highlights those with residual platelet reactivity. TF is stored in open canalicular system, and its membrane exposure upon activation is prevented by colchicine.

Pro-resolving and pro-inflammatory fatty acid-derived mediators in sputum of stable state bronchiectasis patients

BACKGROUND

Bronchiectasis is characterized by neutrophilic inflammation and frequent exacerbations often associated with infections. Lipid mediators play critical roles in the inflammatory response, and the balance between anti-inflammatory and pro-inflammatory mediators could drive to chronic inflammation. The aim of this study was to evaluate the metabolites of docosahexaenoic acid and arachidonic acid in sputum of adults with bronchiectasis defining their associations with clinical data, bacterial load and neutrophil elastase.

METHODS

An observational, cross-sectional study was conducted at the bronchiectasis program of the Policlinico Hospital in Milan, Italy, where patients were enrolled. Active neutrophil elastase was measured by enzyme-linked immunosorbent assay, pro-resolving and pro-inflammatory fatty acid-derived mediators were evaluated by mass spectrometry and respiratory pathogens were assessed by real-time PCR. Analysis were performed on sputum collected during stable state and clinical data were also collected.

RESULTS

Levels of pro-inflammatory mediators derived from arachidonic acid metabolism showed association with neutrophil elastase, were proportional to Pseudomonas aeruginosa identifications and were linked with radiological gravity index, while the concentrations of pro-resolution mediators derived from docosahexaenoic acid were associated with a better health status, highlighted by the inverse correlation with radiological gravity index, bacterial infections and sputum volume production.

CONCLUSION

Pro-inflammatory mediators derived from FA metabolisms are associated with severity of bronchiectasis while DHA-derived metabolites are inversely associated with severity of the disease, which may be used for personized treatment of bronchiectasis.

ERα-independent NRF2-mediated immunoregulatory activity of tamoxifen

Sex differences in immune-mediated diseases are linked to the activity of estrogens on innate immunity cells, including macrophages. Tamoxifen (TAM) is a selective estrogen receptor modulator (SERM) used in estrogen receptor-alpha (ERα)-dependent breast cancers and off-target indications such as infections, although the immune activity of TAM and its active metabolite, 4-OH tamoxifen (4HT), is poorly characterized. Here, we aimed at investigating the endocrine and immune activity of these SERMs in macrophages. Using primary cultures of female mouse macrophages, we analyzed the expression of immune mediators and activation of effector functions in competition experiments with SERMs and 17β-estradiol (E2) or the bacterial endotoxin LPS. We observed that 4HT and TAM induce estrogen antagonist effects when used at nanomolar concentrations, while pharmacological concentrations that are reached by TAM in clinical settings regulate the expression of VEGFα and other immune activation genes by ERα- and G protein-coupled receptor 1 (GPER1)-independent mechanisms that involve NRF2 through PI3K/Akt-dependent mechanisms. Importantly, we observed that SERMs potentiate cell phagocytosis and modify the effects of LPS on the expression of inflammatory cytokines, such as TNFα and IL1β, with an overall increase in cell inflammatory phenotype, further sustained by potentiation of IL1β secretion through caspase-1 activation. Altogether, our data unravel a novel molecular mechanism and immune functions for TAM and 4HT, sustaining their repurposing in infective and other estrogen receptors-unrelated pathologies.

Blood Fatty Acids Profile in MIS-C Children

MIS-C (multisystem inflammatory syndrome in children) linked to SARS-CoV-2 infection, is a pathological state observed in subjects younger than 21 years old with evidence of either current SARS-CoV-2 infection or exposure within the 4 weeks prior to the onset of symptoms, the presence of documented fever, elevated markers of inflammation, at least two signs of multisystem involvement, and, finally, lack of an alternative diagnosis. They share with adult COVID-19 patients the presence of altered markers of inflammation, but unlike most adults the symptoms are not pulmonary but are affecting several organs. Lipid mediators arising from polyunsaturated fatty acids (PUFA) play an important role in the inflammatory response, with arachidonic acid-derived compounds, such as prostaglandins and leukotrienes, mainly pro-inflammatory and ω3 PUFA metabolites such as resolvins and protectins, showing anti-inflammatory and pro-resolution activities. In order to assess potential alterations of these FA, we evaluated the blood fatty acid profile of MIS-C children at admission to the hospital, together with biochemical, metabolic and clinical assessment. All the patients enrolled showed altered inflammatory parameters with fibrinogen, D-dimer, NT-proBNP, ferritin, aspartate aminotransferase (AST), C-reactive protein (CRP) and TrygIndex levels over the reference values in all the subjects under observation, while albumin and HDL-cholesterol resulted below the normal range. Interestingly, linoleic acid (LA), arachidonic acid (AA) and the ω3 PUFA docosahexaenoic acid (DHA) results were lower in our study when compared to relative amounts reported in the other studies, including from our own laboratory. This significant alteration is pointing out to a potential depletion of these PUFA as a result of the systemic inflammatory condition typical of these patients, suggesting that LA- and AA-derived metabolites may play a critical role in this pathological state, while ω3 PUFA-derived pro-resolution metabolites in these subjects may not be able to provide a timely, physiological counterbalance to the formation of pro-inflammatory lipid mediators. In conclusion, this observational study provides evidence of FA alterations in MIS-C children, suggesting a significant contribution of ω6 FA to the observed inflammatory state, and supporting a potential dietary intervention to restore an appropriate balance among the FAs capable of promoting the resolution of the observed inflammatory condition.

Proanthocyanidins from Vitis vinifera inhibit oxidative stress-induced vascular impairment in pulmonary arteries from diabetic rats

BACKGROUND

Vitis vinifera L. (grape seed extract) is a natural source of proanthocyanidins with antioxidant and free radical-scavenging activities.

HYPOTHESIS

Grape seed extract supplementation may prevent vascular endothelium impairment associated with diabetes mellitus in rat pulmonary artery.

STUDY DESIGN

We evaluated endothelial function of rat pulmonary artery ex-vivo at the intermediate stage (4 weeks) of streptozotocin (STZ)-induced diabetes mellitus. We also evaluated the protective effect of grape seed extract administered daily, beginning the day after diabetes induction, or 15 days after diabetes induction, until the day of sacrifice. In addition, we compared the effect of grape seed extract supplementation with that of vitamin C.

METHODS

Rats were made diabetic with streptozotocin (STZ, 65mg/kg i.v.). Thirty days later rats were sacrificed and pulmonary vessels reactivity and endothelial function compared to that of age-matched healthy animals.

RESULTS

Concentration-response curves to ACh, NE, sodium nitroprusside (NO donor), but not to histamine and iloprost (prostacyclin analog), were significantly altered 4 weeks after STZ-injection. Antioxidant supplementation (3mg/kg/day) with either vitamin C or grape seed extract, starting the day after diabetes induction, significantly improved vasodilation to ACh and SNP. Norepinephrine-induced contractions were preserved by grape seed extract, but not vitamin C supplementation. Conversely, vitamin C but not grape seed extract showed beneficial effects contrasting the loss of body weight in diabetic animals. Abnormal vascular function was not reversed when antioxidant supplementations were postponed 15 days after the induction of diabetes.

CONCLUSIONS

This study provides scientific support for the therapeutic potential of an antioxidant therapy in endothelial impairment associated with diabetes. A daily supplementation of grape seed proanthocyanidins and/or vitamin C given at the earlier stage of disease may have a complementary role in the pharmacological therapy of diabetes and pulmonary vascular dysfunction.

In vitro effect of dietary protein level and nondigestible oligosaccharides on feline fecal microbiota

The aim of the present study was to evaluate in vitro the effect of some prebiotic substances and 2 dietary protein levels on the composition and activity of feline fecal microbiota. Two in vitro studies were conducted. First, 6 nondigestible oligosaccharides were studied; treatments were control diet (CTRL), gluconic acid (GA), carrot fiber (CF), fructooligosaccharides (FOS), galactooligosaccharides (GOS), lactitol (LAC), and pectins from citrus fruit (PEC). Substrates were added to feline fecal cultures at 2 g/L for 24 h incubation. Compared with the CTRL, ammonia had been reduced (P<0.05) by GOS (-9%) after 6 h and by GA (-14%), LAC (-12%), and PEC (-10%) after 24 h. After 24 h, all treatments had resulted in a lower pH versus the CTRL. Putrescine concentrations at 24 h were greater (P<0.05) in cultures treated with FOS (+90%), GOS (+96%), and LAC (+87%). Compared with the CTRL, total VFA were higher (P<0.05) in bottles containing CF (+41%), whereas the acetic to propionic acid ratio was reduced by LAC (-51%; P<0.05). After 24 h, Enterobacteriaceae had been reduced (P<0.05) by LAC and PEC. In a second study, LAC and FOS were selected to be tested in the presence of 2 diets differing in their protein content. There were 6 treatments: low-protein (LP) CTRL with no addition of prebiotics (CTRL-LP), high-protein (HP) CTRL with no addition of prebiotics (CTRL-HP), LP diet plus FOS, CTRL-HP plus FOS, LP diet plus LAC, and CTRL-HP plus LAC. Both FOS and LAC were added to feline fecal cultures at 2 g/L for 24 h incubation. Ammonia at 24 h was affected (P<0.05) by the protein level (36.2 vs. 50.2 mmol/L for LP and HP, respectively). The CTRL-HPs resulted in a higher pH and increased concentrations of biogenic amines were found after 6 and 24 h of incubation (P<0.05); putrescine at 24 h showed an increase (P<0.05) in cultures treated with FOS. Total VFA were influenced (P<0.05) by the protein level (40.9 vs. 32.6 mmol/L for LP and HP, respectively). At 24 h, the CTRL-HPs were associated with increased Clostridium perfringens and reduced Lactobacillus spp. and enterococci counts (P<0.05). The results from the present study show that different prebiotics exert different effects on the composition and activity of feline intestinal microbiota and that high dietary protein levels in a cat's diet can have negative effects on the animal intestinal environment.

Cyclooxygenase-1 and prostacyclin production by endothelial cells in the presence of mild oxidative stress

This study aimed at evaluating the relative contribution of endothelial cyclooxygenase-1 and -2 (COX-1 and COX-2) to prostacyclin (PGI₂) production in the presence of mild oxidative stress resulting from autooxidation of polyphenols such as (-)-epigallocatechin 3-gallate (EGCG), using both endothelial cells in culture and isolated blood vessels. EGCG treatment resulted in an increase in hydrogen peroxide formation in human umbilical vein endothelial cells. In the presence of exogenous arachidonic acid and EGCG, PGI₂ production was preferentially inhibited by a selective COX-1 inhibitor. This effect of selective inhibition was also substantially reversed by catalase. In addition, EGCG caused vasorelaxation of rat aortic ring only partially abolished by a nitric oxide synthase inhibitor. Concomitant treatment with a selective COX-1 inhibitor completely prevented the vasorelaxation as well as the increase in PGI₂ accumulation in the perfusate observed in EGCG-treated aortic rings, while a selective COX-2 inhibitor was completely uneffective. Our data strongly support the notions that H₂O₂ generation affects endothelial PGI₂ production, making COX-1, and not COX-2, the main source of endothelial PGI₂ under altered oxidative tone conditions. These results might be relevant to the reappraisal of the impact of COX inhibitors on vascular PGI₂ production in patients undergoing significant oxidative stress.

MicroRNA 143-145 deficiency impairs vascular function

MicroRNAs are required for vascular smooth muscle growth, differentiation and function. MiR143-145 modulates cytoskeletal dynamics and acquisition of the contractile phenotype by smooth muscle cells. Lack of this miRNA cluster results in decreased blood pressure and reduced vasocontraction. As all these observations point to a key role for miR143-145 in the vasculature, we investigated whether miR143-145 deficiency is associated with impaired vascular tone. Vasocontraction was assessed in isolated aortic rings from miR143-145 KO and wild type animals incubated with increasing concentrations of phenylephrine (10(-9)M to 10(-5)M) or KCl 0.3M. In both cases, aortic vessel contraction was dramatically reduced in miR143-145 KO animals compared to controls. Next, aortic rings were pre-contracted with phenylephrine (EC60: 10(-7)M) and concentration responses for acetylcholine were obtained. A significantly reduced vasodilation was observed in miR143-145 KO animals compared to controls and similar results were obtained when an exogenous donor of nitric oxide (sodium nitroprusside) was used. Endothelial nitric oxide synthase or guanylate cyclase mRNA expression were not different between the animal groups thus suggesting to investigate the effect of other vasodilators. Isoprenaline mediated vasodilation was significantly reduced in miR143-145 KO animals compared to controls in the absence or in the presence of the guanylate cyclase inhibitor ODQ (10(-4)M), suggesting that also beta adrenergic vasodilation is impaired following miR143-145 deficiency. Finally, the effect of a stable mimetic prostacyclin, namely iloprost, was investigated and again a reduced vasodilation was observed in miR143-145 KO animals. MiR143-145 deficiency is associated not only with altered vasocontraction but also with impaired vasodilation, which probably reflects the impaired VSMC differentiation phenotype reported in miR143-145 KO animals.

Selective estrogen receptor-alpha agonist provides widespread heart and vascular protection with enhanced endothelial progenitor cell mobilization in the absence of uterotrophic action

The beneficial effects of estrogens on the cardiovascular system are associated with adverse effects on reproductive tissues. On the basis of previous work indicating a major role for estrogen receptor (ER)-alpha in maintaining cardiovascular health, we evaluated the tissue selectivity of the ER alpha-selective agonist propyl pyrazole triol (PPT) compared with 17beta-estradiol (E2) in vivo. Four weeks postovariectomy, equimolar doses of PPT and E2 were administered to rats in subcutaneous implants for 5 d. Both treatments restored rapid vasorelaxation of aortic tissue to estrogenic agents and prevented coronary hyperresponsiveness to angiotensin II in isolated heart preparations. Accordingly, multiple endpoints of myocardial ischemia-reperfusion injury exacerbated by ovariectomy returned to baseline following treatment. These protective effects were linked to increased in vivo levels of endothelial progenitor cells (EPCs). Human EPC function was enhanced in vitro after PPT treatment. In sharp contrast to E2, PPT treatment had no effect on uterine weight and histomorphology except for vessel density, and failed to up-regulate classic estrogen target genes. Dissection of the effects on vascular reactivity and uterine morphology was also observed following increased exposure to PPT at a higher dose for longer time. These data provide the first in vivo evidence for tissue-specific ER alpha activation. By conferring cardiovascular protection dissected from unwanted uterotrophic effects, ER alpha-selective agonists may represent a potential safer alternative to natural hormones.

Distinct roles of estrogen receptor-alpha and beta in the modulation of vascular inducible nitric-oxide synthase in diabetes

Estrogen is known to affect vascular function and diabetes development, but the relative contribution of estrogen receptor (ER) isoforms is unclear. The aim of this study was to determine how individual ER isoforms modulate inflammatory enzymes in the vascular wall of control and streptozotocin (STZ)-injected rodents. Primary cultures of rat aortic smooth muscle cells (SMCs) were stimulated with inflammatory agents in the presence or absence of increasing concentrations of the ER alpha and ER beta-selective agonists 4,4',4''-(4-propyl-[1H]-pyrazole-1,3,5-triyl)trisphenol (PPT) and diarylpropionitrile (DPN), respectively. The production of inducible nitric-oxide synthase (iNOS), a classical indicator of vascular inflammation, was significantly reduced by PPT in control but not diabetic SMCs, whereas it was further enhanced by DPN treatment in both groups. This distinct action profile was not related to changes in ER transcriptional activity. However, extracellular signal-regulated kinase 1/2 signaling was activated by DPN but not by PPT in cytokine-treated SMCs. In cultured aortic rings from both normoglycemic and STZ-diabetic mice, pharmacological activation of ER alpha attenuated cytokine-driven iNOS induction by 30 to 50%. Vascular iNOS levels were decreased consistently when adding 1 nM 17beta-estradiol to aortic tissues from ER beta- but not ER alpha-knockout mice. These findings suggest a possible role for ER alpha-selective ligands in reducing vascular inflammatory responses under normo- and hyperglycemic conditions.

Prolonged Ovarian Hormone Deprivation Impairs the Protective Vascular Actions of Estrogen Receptor αAgonists

The vascular consequences of estrogen treatment may be driven by its initiation timing. We tested the hypothesis that the duration of ovarian hormone deprivation before estrogen reintroduction affects the role of estrogen as mediator of endothelial function and vascular relaxation in nondiseased vessels. Rats were ovariectomized and implanted with 17β-estradiol (E 2 ) or oil capsules 1, 4, and 8 months after surgery. After the longest hypoestrogenicity period, acetylcholine-mediated aortic relaxation was attenuated and insensitive to E 2 administration despite endothelial integrity. Whereas no rapid vasorelaxant responses were elicited by an estrogen receptor (ER) β–selective agonist, responses to E 2 and an ERα selective agonist waned postovariectomy at any given time and were restored by E 2 treatment after 1 and 4 months but not 8 months postovariectomy. Accordingly, endothelial ERα mRNA and protein expression declined ≈6-fold after prolonged hypoestrogenicity and was restored by estrogen replacement starting 1 month but not 8 months postovariectomy. Furthermore, the amount of active phosphorylated endothelial NO synthase rose significantly after E 2 replacement after 1 and 4 months but not 8 months postovariectomy. The present findings document that the functional impairment of the ERα/endothelial NO synthase signaling network after an extended period of hypoestrogenicity was not restored by E 2 administration, providing experimental support to early initiation of estrogen replacement with preferential ERα targeting to improve cardiovascular outcomes.

Selective Agonists of Estrogen Receptor Isoforms

The cloning of estrogen receptors (ERs) and generation of ER-deficient mice have increased our understanding of the molecular mechanisms underlying the cardiovascular effects of estrogen. It is conceivable that clinical trials of estrogens so far failed to improve cardiovascular health because of the poor ER isoform selectivity and tissue specificity of endogenous hormones as well as incorrect treatment timing and regimens. Tissue-selective ER modulators (SERMs) may be safer agents than endogenous estrogens for cardiovascular disease. Yet, designing isoform-selective ER ligands (I-SERMs) with agonist or antagonist activity is required to pursue improved pharmacological control of ERs, especially taking into account emerging evidence for the beneficial role of vascular ER alpha activation. Ideally, the quest for unique ER ligands targeted to the vascular wall should lead to compounds that merge the pharmacological profiles of SERM and I-SERM agents. This review highlights the current bases for and approaches to selective ER modulation in the cardiovascular system.

Raloxifene elicits combined rapid vasorelaxation and long-term anti-inflammatory actions in rat aorta

Previous studies reported the ability of raloxifene to acutely relax arterial and venous vessels, but the underlying mechanisms are controversial. Anti-inflammatory effects of the drug have been reported in nonvascular tissues. Therefore, the aim of this study was to investigate the nature of short- and long-term effects of raloxifene on selected aspects of vascular function in rat aorta. Isometric tension changes in response to raloxifene were recorded in aortic rings from ovariectomized female rats that underwent estrogen replacement, whereas long-term experiments were performed in isolated aortic smooth muscle cells (SMCs). Raloxifene (0.1 pM-0.1 microM) induced acute vasorelaxation through endothelium- and nitric oxide (NO)-dependent, prostanoid-independent mechanisms. The relaxant response to raloxifene was significantly weaker than that to 17beta-estradiol and was sensitive to neither the nonselective estrogen receptor antagonist ICI 182,780 [7,17-[9[(4,4,5,5,5-pentafluoropentyl)sulfinyl]nonyl]estra-1,3,5(10)-triene-3,17-diol] nor a selective estrogen receptor (ER) alpha antagonist. This rapid vasorelaxant effect was retained in aortic rings from rats treated with 0.1 mg/kg, but not 1 mg/kg, lipopolysaccharide, 4 h before sacrifice. In cultured aortic SMCs, raloxifene treatment (1 nM-1 microM) for 24 h reduced inducible NO synthase activation in response to cytokines. This effect was prevented by the selective ERalpha antagonist and was associated with up-regulation of ERalpha protein levels, which dropped markedly upon cytokine stimulation. These findings illustrate the relevance of classic ER-dependent pathways to the vascular anti-inflammatory effects rather than to the nongenomic vasorelaxation induced by raloxifene and may assist in the design of novel ER isoform-selective estrogen-receptor modulators targeted to the vascular system.

Potential pro-inflammatory action of resveratrol in vascular smooth muscle cells from normal and diabetic rats

BACKGROUND AND AIM

Based on the reported cardioprotective effects of resveratrol, a polyphenolic antioxidant abundant in grapes that binds to estrogen receptors, and the well-characterized anti-inflammatory properties of 17beta-estradiol, the effects of resveratrol on the functional expression of inflammatory enzymes were assessed in vascular smooth muscle cells (SMC) from normoglycaemic and streptozotocin-diabetic rats.

METHODS AND RESULTS

SMC were isolated from the aorta four weeks after treating rats with streptozotocin or its vehicle. In SMC exposed to a cytokine mixture for 24h, unexpectedly, treatment with resveratrol (0.1-100microM) as well as the structurally related isoflavone genistein (1nM-1microM) enhanced expression of inducible NO synthase (iNOS). Genistein failed to mimic the elevated iNOS activity induced by resveratrol. Inhibition of estrogen receptors by the pure antiestrogen ICI 182,780 reversed the action of resveratrol on iNOS. In addition, resveratrol failed to alter cyclooxygenase-2 protein levels but reduced the accumulation of prostaglandin E(2) in the culture medium of SMC from normoglycaemic, but not diabetic rats.

CONCLUSIONS

These results indicate that resveratrol, at concentrations approaching putative peak plasma levels in vivo, exhibited no anti-inflammatory properties in vascular SMC from normal and diabetic rats. By contrast, resveratrol displayed a potential pro-inflammatory activity in settings of vascular inflammation.

Altered neurogenic and mechanical responses to acetylcholine, ATP and substance P in detrusor from rat with outlet obstruction

The well-known side effects of anticholinergic compounds used to treat urinary incontinence caused by detrusor overactivity have addressed the interest on other pharmacological intervention. The purpose of the present work was to investigate the possible changes in purinergic and cholinergic components of parasympathetic neurotransmission in obstructed rat bladders with detrusor overactivity, and to examine the effect of the association of suramin, atropine and indomethacin on nerve-mediated responses to electrical field stimulation (EFS). Mechanical responses to exogenous acetylcholine, ATP and substance P were also evaluated. Altered sensitivities to acetylcholine and to the sensory neurotransmitter substance P, but unchanged sensitivity to the stable ATP analogue alpha,beta-methyleneATP were observed in bladders from obstructed rats. Suramin and atropine inhibited purinergic and cholinergic components of the neurogenic responses evoked by EFS in detrusor strips from control and obstructed rats. Interestingly, suramin enhanced the antagonistic effect of atropine on neurogenic responses of detrusor strips at all frequencies of stimulation tested. Our results suggest that the association between an antimuscarinic drug and an antagonist of P2X purinoceptors such as suramin might be helpful to reduce the therapeutic dosage of the antimuscarinic drug, along with its side effects. This approach may be of interest in the therapy of patients with bladder incontinence caused by detrusor overactivity, which do not even respond to a maximal dosage of antimuscarinic drug.

Wernicke's encephalopathy in a malnourished surgical patient: clinical features and magnetic resonance imaging

We report a clinical and neuroradiological description of a severe case of Wernicke's encephalopathy in a surgical patient. After colonic surgery for neoplasm, he was treated for a long time with high glucose concentration total parenteral nutrition. In the early post-operative period, the patient showed severe encephalopathy with ataxia, ophthalmoplegia and consciousness disorders. We used magnetic resonance imaging (MRI) to confirm the clinical suspicion of Wernicke's encephalopathy. The radiological feature showed hyperintense lesions which were symmetrically distributed along the bulbo-pontine tegmentum, the tectum of the mid-brain, the periacqueductal grey substance, the hypothalamus and the medial periventricular parts of the thalamus. This progressed to typical Wernicke-Korsakoff syndrome with ataxia and memory and cognitive defects. Thiamine deficiency is a re-emerging problem in non-alcoholic patients and it may develop in surgical patients with risk factors such as malnutrition, prolonged vomiting and long-term high glucose concentration parenteral nutrition.

Effect of the ATP-sensitive potassium channel opener ZM226600 on cystometric parameters in rats with ligature-intact, partial urethral obstruction

The activity of a recent K(ATP) channel opener, the N-(4-Phenylsulfonylphenyl)-3,3,3-trifluoro-2-hydroxy-2-methylpropionamide (ZM226600) was investigated on a female rat model of overactive bladder with outlet obstruction. Both ZM226600 and pinacidil instilled into the bladder (10(-7) M, 30 min) or following systemic administration (10, 100 nmol/kg e.v.) almost completely abolished bladder overactivity and improved residual volume and frequency of micturition. However, pinacidil affected arterial pressure. Oxybutynin instilled into the bladder (10(-7), 10(-6), 10(-5) M, 30 min) decreased detrusor overactivity by about 16%, 25% and 46% respectively, but also blocked micturition reflexes at highest doses tested. Oxybutynin reduced detrusor overactivity by about 50% and 80%, after systemic administration (10, 100 nmol/kg e.v.), but also blocked micturition reflexes at the highest dose tested. In conclusion, ZM226600 is more active than oxybutynin in reducing bladder overactivity, and it is devoid of vascular side effects observed with pinacidil. Its short duration of action (about 1 h) is probably the main problem to solve, in order to consider this compound a valid alternative to antimuscarinics in the therapy of bladder overactivity.

Purine- and pyrimidine-induced responses and P2Y receptor characterization in the hamster proximal urethra

1. Purine and pyrimidine compounds were investigated on hamster proximal urethral circular smooth muscle preparations. In situ hybridization studies were carried out to localize P2Y(1), P2Y(2), P2Y(4) and P2Y(6) mRNA. Protein expression was studied using Western blotting analysis with antibodies against P2Y(1) and P2Y(2) receptors. 2. The hamster urethra relaxed with an agonist potency order of: 2-MeSADP>beta,gamma-meATP=ATP=adenosine=ADP>2-MeSATP>alpha,beta-meATP>TTP>CTP=UTP>GTP=UDP. The high potency of 2-MeSADP is suggestive of an action via P2Y(1) receptors. Although the order is not characteristic for any known single P2Y receptor subtype, it may represent a combination of P2Y receptor subtypes. 4. The selective P2Y(1) receptor antagonist MRS2179 inhibited ATP-, 2-MeSADP-, 2-MeSATP-, beta,gamma-meATP-, and to a lesser degree alpha,beta-meATP-induced responses. 3. Adenosine, but not ATP, was inhibited by the adenosine receptor antagonist 8-phenyltheophylline, indicating that ATP was not acting via adenosine following enzymatic breakdown. 5. Western blotting analysis showed the expression of both P2Y(1) and P2Y(2) receptors, confirming the results obtained with in situ hybridization that showed the expression of both P2Y(1) and P2Y(2), but not P2Y(4) or P2Y(6) mRNA, in smooth muscle layers of the hamster proximal urethra. 6. It is proposed that the relaxant response of the urethra to ATP may be evoked through the activation of the combination of receptors for P2Y(1) and to a lesser extent P2Y(2) receptors, which may mediate a trophic effect in addition. A P2Y subtype responsive to alpha,beta-meATP and P1 receptors may contribute to urethral smooth muscle relaxation.

The Acute Estrogenic Dilation of Rat Aorta Is Mediated Solely by Selective Estrogen Receptor-α Agonists and Is Abolished by Estrogen Deprivation

Estrogen is known to induce rapid vasodilatory response in isolated arteries. Because estrogen is a nonselective receptor agonist, the involvement of estrogen receptor (ER) subtypes in acute estrogenic responses has remained elusive. Acute administration of the selective ERalpha agonist 4,4',4''-(4-propyl-[(1)H]pyrazole-1,3,5-triyl) tris-phenol (PPT) to precontracted aortic rings from intact female rats dose-dependently induced an ER-dependent vascular relaxation fully overlapping to that induced by 17beta-estradiol. By contrast, the selective ERbeta agonist 2,3-bis(4-hydroxyphenyl)-propionitrile (DPN) had no acute effect on vasomotion. This short-term vasorelaxant action of PPT was abolished by the NO synthase inhibitor N(omega)-nitro-l-arginine methyl ester and by endothelium removal. In aortic tissues from ovariectomized (OVX) rats, however, neither 17beta-estradiol nor PPT induced acute vascular relaxation. The effect of PPT was restored in preparations from estrogen-replaced OVX rats, whereas DPN remained ineffective even after estrogen replacement. PPT acted through an ER-dependent mechanism, as shown by impaired response in the presence of the anti-estrogen ICI 182,780 (7alpha,17beta-[9[(4,4,5,5,5-pentafluoropentyl)sulfinyl]nonyl]estra-1,3,5(10)-triene-3,17-diol). Accordingly, isolated rat aortic endothelial cells expressed both ERalpha and ERbeta. These data show that selective ERalpha but not ERbeta agonists reproduced the acute vasodilation of estrogen via a receptor-mediated pathway in the aorta from intact as well as 17beta-estradiol-replaced OVX rats. This beneficial effect was undetectable in tissues from OVX rats. Selective pharmacological targeting of ER subtypes may thus represent a novel and promising approach in the treatment of vascular disease.

Development of the first ultra-potent "capsaicinoid" agonist at transient receptor potential vanilloid type 1 (TRPV1) channels and its therapeutic potential

Olvanil (N-9-Z-octadecenoyl-vanillamide) is an agonist of transient receptor potential vanilloid type 1 (TRPV1) channels that lack the pungency of capsaicin and was developed as an oral analgesic. Vanillamides are unmatched in terms of structural simplicity, straightforward synthesis, and safety compared with the more powerful TRPV1 agonists, like the structurally complex phorboid compound resiniferatoxin. We have modified the fatty acyl chain of olvanil to obtain ultra-potent analogs. The insertion of a hydroxyl group at C-12 yielded a compound named rinvanil, after ricinoleic acid, significantly less potent than olvanil (EC(50) = 6 versus 0.7 nM), but more versatile in terms of structural modifications because of the presence of an additional functional group. Acetylation and phenylacetylation of rinvanil re-established and dramatically enhanced, respectively, its potency at hTRPV1. With a two-digit picomolar EC(50) (90 pM), phenylacetylrinvanil (PhAR, IDN5890) is the most potent vanillamide ever described with potency comparable with that of resiniferatoxin (EC(50), 11 pM). Benzoyl- and phenylpropionylrinvanil were as potent and less potent than PhAR, respectively, whereas configurational inversion to ent-PhAR and cyclopropanation (but not hydrogenation or epoxidation) of the double bond were tolerated. Finally, iodination of the aromatic hydroxyl caused a dramatic switch in functional activity, generating compounds that behaved as TRPV1 antagonists rather than agonists. Since the potency of PhAR was maintained in rat dorsal root ganglion neurons and, particularly, in the rat urinary bladder, this compound was investigated in an in vivo rat model of urinary incontinence and proved as effective as resiniferatoxin at reducing bladder detrusor overactivity.

Diabetes undermines estrogen control of inducible nitric oxide synthase function in rat aortic smooth muscle cells through overexpression of estrogen receptor-beta

BACKGROUND

Previous reports from our group have shown that 17beta-estradiol reduces the synthesis and activity of inducible nitric oxide synthase (iNOS) in rat aortic smooth muscle cells (SMC) in response to inflammatory mediators. In this study, we investigated the effect of 17beta-estradiol on iNOS function in aortic SMC from streptozotocin-diabetic rats.

METHODS AND RESULTS

Comparative analysis of NO release and of iNOS mRNA and protein content after 24-hour stimulation with a cytokine mixture revealed milder iNOS activation in diabetic than in control SMC. Furthermore, 17beta-estradiol dose-dependently blocked iNOS synthesis and activity in control but not in diabetic SMC. The defective estrogen response in diabetic SMC at 24 hours could not be attributed to reduced expression of estrogen receptors (ER). In fact, mRNA and protein levels of ERalpha and, to a greater extent, of ERbeta, were increased in diabetic compared with nondiabetic SMC. Cytokines decreased ERalpha and ERbeta expression in both groups. However, 17beta-estradiol dose-dependently restored the expression of ERalpha but further downregulated that of ERbeta, indicating a differential regulation of ER isoforms.

CONCLUSIONS

Estrogenic control of iNOS was impaired in diabetic SMC. This was associated with a larger increase of ERbeta than of ERalpha protein, whereas 17beta-estradiol regulated the two isoforms in an opposite fashion. Thus, modifications in the estrogen modulation of iNOS and in the expression pattern of ER may be involved in diabetic vascular dysfunction.

Sustained normalization of cerebral blood-flow after iloprost therapy in a patient with neuropsychiatric systemic lupus erythematosus

We report the case of a 30-year-old caucasian woman affected by SLE who developed neurological symptoms (prosopagnosia and visual-spatial agnosia) after nine years of disease. Brain MRI showed no abnormalities while a brain SPECT scan showed diffuse uptake defects and hypoperfusion areas in the right and left frontal-parietal regions. At that time the patient was on hydroxychloroquine (400 mg/day) and oral prednisolone (0.5 mg/kg/day) as maintenance therapy. One year later the patient showed worsening of Raynaud's phenomenon with digital dystrophic lesions and was therefore treated with an intravenous infusion of Iloprost (1.5 ng/kg/min per 6h/day for 10 days consecutively), while baseline treatment remained unchanged. One month later the patient showed a dramatic improvement in her cognitive function and subsequent SPECT scans showed the gradual disappearance of perfusion abnormalities. This first report of Iloprost treatment in CNS lupus suggests the potential therapeutic usefulness of this drug in patients with SLE and functional CNS involvement.

Monitoring the effects of drug treatment in rat models of disease by serum protein analysis

In this review we list from literature investigations on rat serum proteins using electrophoretic techniques in connection with drug testing. From our own research work, we provide annotated two-dimensional maps of rat serum proteins under control and experimental conditions. Emphasis is on species-specific components and on the effects of acute and chronic inflammation. We discuss our project of structural proteomics on rat serum as a minimally invasive approach to pharmacological investigation, and we outline a typical experimental plan for drug testing according to the above guidelines. We then report in detail on the results of our trials of anti-inflammatory drugs on adjuvant arthritis, an animal model of disease resembling in many aspects human rheumatoid arthritis. We demonstrate a correlation between biochemical parameters and therapeutic findings and outline the advantages of the chosen methodological approach, which proved also sensitive in revealing "side effects" of the test drugs. In an appendix we describe our experimental protocol when performing two-dimensional electrophoresis of rat serum.

Gender differences and antioxidant treatment affect aortic reactivity in short-term diabetic rats

Diabetes is associated with gender-specific macrovascular complications arising from increased oxidant stress in the vascular wall. In this study, male and female rats were treated with two structurally unrelated drugs sharing antioxidant properties, lercanidipine and Leucoselect (both 3 mg/kg/day), for 1 week starting 1 day after streptozotocin-diabetes induction. Concentration-response curves to L-nitroarginine methylester (L-NAME), superoxide dismutase and acetylcholine in aortic rings showed significantly greater nitric oxide-mediated relaxation in female compared with male non-diabetic rats. Diabetes increased contractility to noradrenaline and L-NAME in both genders, whereas relaxation to acetylcholine and iloprost were significantly attenuated in females only. Treatment with lercanidipine and Leucoselect restored, at least in part, responses to noradrenaline, acetylcholine and iloprost without affecting those to L-NAME and sodium nitroprusside. Unexpectedly, both drugs impaired superoxide dismutase response in female tissues. In conclusion, female rat aorta is markedly exposed to short-term diabetic vascular injury, which may be prevented by antioxidant treatment.

Differential induction of spermidine/spermine N1-acetyltransferase activity in cisplatin-sensitive and -resistant ovarian cancer cells in response to N1,N12-bis(ethyl)spermine involves transcriptional and post-transcriptional regulation

The growth inhibition that occurs in cisplatin-sensitive 2008 human ovarian cancer cells in response to the spermine analogue, N1,N12-bis(ethyl)spermine (BESpm), is associated with a potent induction of spermidine/spermine N1-acetyltransferase (SSAT), the rate-limiting enzyme in polyamine catabolism. Conversely, in cisplatin-resistant C13* cells, which are less responsive to BESpm, enzyme induction does not occur at comparable levels after exposure to the bis(ethyl)-derivative. In this study, we investigated the molecular mechanisms underlying the differential induction of SSAT activity in cisplatin-sensitive and -resistant cells. Northern blot analysis revealed a difference in the level of SSAT mRNA expression in the two cell lines; in particular, 2008 cells treated with 10 microM BESpm for progressively increasing periods of time accumulated more heteronuclear (3.5 kb) and mature (1.3/1.5 kb) SSAT mRNAs than its resistant variant. SSAT mRNA accumulation paralleled enzyme activity and both were almost completely prevented in the two lines by co-treatment with 5 microg/ml actinomycin-D (Act-D), suggesting that transcription plays a major role in the analogue-mediated induction of SSAT. Moreover, when Act-D was added 48 h after BESpm exposure, SSAT mRNA and enzyme activity were stabilised in both cell lines. Therefore, the marked difference in the induction of SSAT activity seems to be related to increased enzyme synthesis, particularly in sensitive cells, whose SSAT protein turnover was also greatly reduced (half-life >12 h in 2008 cells versus 5 h in C13* cells) in the presence of BESpm. These findings suggest that cisplatin-resistance modulates the SSAT response to BESpm at transcriptional and post-transcriptional levels.

Increased levels of clusterin (SGP-2) mRNA and protein accompany rat ventral prostate involution following finasteride treatment

Finasteride is a well-known inhibitor of the prostatic enzyme 5 alpha-reductase type 2 which prevents conversion of testosterone into 5 alpha-dihydrotestosterone, the active intraprostatic androgen, which causes prostate involution through a combination of cell atrophy and cell death. The drug is widely used to improve symptoms of benign prostatic hyperplasia in man. Clusterin, a glycoprotein which is generally up-regulated under conditions inducing cell atrophy or organ involution, is produced at a high level in the regressing rat ventral prostate following androgen ablation. According to several authors, clusterin does not respond to finasteride treatment, suggesting a different action of testosterone and 5 alpha-dihydrotestosterone. We show here that, under our conditions, finasteride was capable of inducing production of both clusterin mRNA and protein in the rat ventral prostate. In fact, by using different and converging techniques, such as Northern hybridization, in situ hybridization histochemistry and immunohistochemistry, we were able to show a strong induction of the clusterin gene in the epithelial cell population of the gland. The response to finasteride, which was similar to that seen with castration, occurred with a delay of a few days. In situ and immunohistochemistry experiments indicated that both orchidectomy and finasteride administration resulted in increased transition of the epithelial cells from the columnar to the cuboidal (atrophic) shape, and this was accompanied by an increased intensity of the signal for clusterin. Thus, it appears that induction of clusterin is part of the molecular process leading to prostate involution caused by either orchidectomy or finasteride administration.

Diabetes influences the effect of 17beta-estradiol on mechanical responses of rat urethra and detrusor strips

Estrogen deficiency is one of the factors involved in the stress incontinence in postmenopausal women, and estrogens have been used clinically in the treatment of urinary disorders during menopause. Sex hormones seem to be also involved in the diabetic changes of urinary bladder and urethra, because ovariectomy causes an increase in the micturition of streptozotocin-diabetic rats. In the present study diabetic and healthy female rats were used to investigate the effect of 17beta-estradiol on mechanical contractions to norepinephrine and to KCI and relaxations to ATP on isolated proximal urethral preparations as well as on contractions to ACh, ATP and KCl on detrusor smooth muscle strips. The data were compared with those obtained in OVX animals, with or without estradiol replacement. The present study showed that ovariectomy decreased the responses to ATP, NE and KCl in urethral preparations, and responses to ATP, ACh and KCl in bladder strips from both healthy and diabetic rats. Diabetes appeared to potentiate the effect of ovariectomy in both tissues. Estrogen replacement was able to recover functional responses in urethras of healthy rats. In diabetic rats, this treatment partially restored ATP-induced responses in both tissues, almost completely restored those to NE in urethra and those to ACh in bladder. This study clearly indicated that abnormalities of urethra and bladder function caused by ovariectomy can be restored by estrogen treatment also in diabetic animals, at least at an early stage of disease.

The influence of sex hormones on vascular responses in the aorta of streptozotocin-diabetic male rats

Diabetes mellitus reduces gender-related differences in the prevalence of cardiovascular disease by fading the vascular protective effects afforded by estrogen in females. However, the impact of estrogen treatment on and the contribution of androgens to vascular function in vessels from male diabetics are largely unknown. We investigated the effects of androgen deficiency and in vivo estrogen treatment by assessing the responsiveness to a number of vasoactive agents and the formation of eicosanoid mediators in aortic rings from intact and castrated streptozotocin-diabetic rats which had been implanted with 17beta-estradiol (E2) or its vehicle for 5 days. Castration was found to attenuate contractility to noradrenaline, to enhance tone-related release of NO, as shown by curves for N-methyl-L-arginine and superoxide dismutase (SOD), and to increase endothelium-dependent relaxation to carbachol and histamine, compared with intact animals. Smooth muscle sensitivity to exogenous NO and platelet thromboxane A2 production were unchanged but prostacyclin release by aortic tissue dropped by about 40% following castration. Treatment with E2 to intact animals still attenuated contractility to noradrenaline and potentiated relaxation to SOD and histamine but affected no other parameters. In contrast, when E2 was administered to castrated animals, responses to SOD, carbachol and histamine were significantly impaired. Thus, androgen deprivation appears to improve vascular function in male diabetic rats, whereas E2 treatment exerts some beneficial effects in intact, but not in castrated animals. Our findings therefore provide new insights into the role of sex hormones in the development of diabetic vascular complications.

Prostaglandin-release impairment in the bladder epithelium of streptozotocin-induced diabetic rats

Isolated epithelial layer preparations were obtained from urinary bladders of 4-week streptozotocin-diabetic rats and used for endogenous prostaglandins E(2) and F(2alpha) determination. Tissues were incubated in modified Krebs solution under basal conditions, or in the presence of either indomethacin (5x10(-7) M), ATP (10(-5) and 10(-3) M) or bradykinin (10(-7) and 10(-5) M), and samples of incubation medium were collected at 15 and 30 min. In the presence of indomethacin, the release of prostaglandins in the incubation medium was under the detection limit of the enzyme immunoassay (EIA). The epithelium from diabetic rat urinary bladders was thicker and heavier and the absolute amount of endogenous prostaglandins E(2) and F(2alpha) was higher than for control animals, but when prostaglandin production was expressed as a fraction of tissue weight, it was reduced in diabetic epithelium. ATP and bradykinin has significantly increased the endogenous release of both prostaglandins from the epithelium when compared with the release under basal conditions. This increase was time-dependent and was higher in diabetic than in control tissues. ATP evoked a phasic and tonic contraction in bladder strips that was abolished by epithelium removal. Concentration-response curves for ATP did not differ among groups. Bradykinin evoked a long-lasting tonic contraction that was reduced significantly by epithelium removal in diabetic rat bladders only. Concentration-response curves for prostaglandin E(2) and F(2alpha) in diabetic rat bladder differed significantly from that in controls and epithelium removal did not alter these responses. It is suggested that bradykinin receptors and P2X nucleotide receptors already found in the smooth muscle detrusor might be present in the epithelial layer of the bladder. The prostaglandin-release impairment observed in this study might be responsible, in part, for bladder abnormalities observed in pathological conditions, such as diabetes.

Androgen deprivation, estrogen treatment and vascular function in male rat aorta

The beneficial effects of estrogen on arterial function in women are well established, whereas studies concerning the vascular role of androgens have produced conflicting results. In the present study, we examined the effects of androgen deprivation and of estrogen treatment on vascular responses in male rats. Vascular reactivity was studied in aortic rings excised from intact and castrated rats, which had been implanted with capsules containing either 17beta-estradiol (E2) or its vehicle for 5 days. Contractile responses to noradrenaline were potentiated by castration and by E2 treatment. Concentration-response curves for N-methyl-L-arginine and superoxide dismutase indicated that the tone-related release of NO increased in tissues from castrated, compared with intact rats, but was not affected by E2 treatment. Endothelium-dependent relaxation elicited by carbachol and histamine were not altered by castration and were attenuated by E2 in preparations from intact, but not from castrated rats. Moreover, aortic prostacyclin release dropped by about 40% after E2 treatment in tissues from both intact and castrated animals. Similarly, smooth muscle sensitivity to NO significantly decreased following castration and E2 treatment, as assessed by responses to sodium nitroprusside. Finally, no differences among groups were detected in platelet thromboxane A2 production. Thus, vascular responses in male rats were not improved by androgen deprivation alone or by E2 treatment, whose effects differed in the presence or absence of androgens. These findings provide evidence for the gender specificity of the vascular effects of estrogen and may be consistent with a beneficial role of physiologic levels of male sex hormones in arterial function.

Different sensitivities of p42 mitogen-activated protein kinase to phorbol ester and okadaic acid tumor promoters among cell types

The operational equivalence of different types of tumor promoters was studied by comparing immediate, early, and late effects of okadaic acid (OA) and 12-O-tetradecanoylphorbol-13-acetate (TPA) on the phosphorylation state of p42 mitogen-activated protein kinase isoform (ERK2) in eight different cell lines. In normal human and mouse fibroblasts, both agents stimulated immediate/early (15-60 min) phosphorylation of ERK2. In mouse 3T3 cells, enhanced phosphorylation of ERK2 was detected only within the first hour of treatment with TPA but not with OA. The early response to both TPA and OA, in turn, was lost in another established cell line, the PNT2 prostate epithelial cells, where we could detect increased levels of phosphorylated ERK2 only after a 24-hr treatment with OA. When the effect of OA was evaluated in different PNT cell strains, we observed that their capacity to respond to this agent, by stabilizing phosphorylated forms of ERK2, was lost in less differentiated strains. In HeLa S3 and HTC tumor cells, however, neither TPA nor OA treatment led to any detectable increase in ERK2 phosphorylation at any time point analyzed. We conclude that the effects of OA and TPA on the phosphorylation states of ERK2 could be related to the cell type, and that the operational equivalence between these two different tumor promoters is maximal in normal cells.

Diabetes abolishes the vascular protective effects of estrogen in female rats

Estrogen is known to exert a protective effect against cardiovascular disease. However, women with diabetes have three times the risk as compared with age-matched non-diabetic women. Our previous study on aortic rings of ovariectomized (OVX) female rats treated with 17-beta-estradiol (E2) demonstrated that the beneficial effect of estrogen is related to the basal release of NO from endothelial cells. In the present study, in order to understand why estrogen protection is abolished in diabetes, we tested vascular responses in OVX, streptozotocin-diabetic female rats and their non-diabetic controls receiving or not E2 replacement. Concentration-response curves to norepinephrine (NE) showed attenuation of the contractile response in E2-treated diabetic, with respect to non-diabetic preparations. This response was further impaired in diabetic, E2-deprived rats. The basal release of NO, as evaluated by concentration-related responses to N(G)-methyl-L-arginine acetate in NE-precontracted aortic rings, was found to be impaired in E2-treated diabetic rats, no further effect being induced by E2 deprivation. The endothelium-dependent relaxation produced by carbachol did not change between groups, whereas the relaxation produced by histamine was enhanced by both diabetes and E2 deprivation. However, E2 treatment counteracted the response to histamine only in preparations from non-diabetic animals. Finally, the relaxation induced by sodium nitroprusside, an endothelium-independent relaxant agent, was comparable between groups. These findings suggest that the lack of protective effects of estrogen in diabetes may be mainly ascribed to the failure of estrogen to reverse the impaired basal release of NO and the abnormal relaxation to histamine, which are observed in the aorta of diabetic rats.

Coordinate changes of polyamine metabolism regulatory proteins during the cell cycle of normal human dermal fibroblasts

In human dermal fibroblasts, brought to quiescence (G0) by serum starvation, the S phase peaked 24 h and G2/M phases 36 h after serum re-addition. Under the same conditions, ornithine decarboxylase mRNA peaked at 12 h, decreased markedly in S phase and remained low until 48 h. Conversely, ornithine decarboxylase antizyme transcript dropped to its lowest level at 12 h, while reaching its highest values between 24 and 48 h. Ornithine decarboxylase activity followed essentially the pattern of its mRNA, but relative changes were much greater. S-Adenosylmethionine decarboxylase transcript and enzyme activity also peaked at around 12 h, decreasing thereafter. Spermidine/spermine N1-acetyltransferase mRNA and activity reached the highest values at 36-48 h. Putrescine concentration increased up to 18 h and fell dramatically in the S phase, remaining low thereafter. Both spermidine and spermine reached peaks at 18 h and decreased in the S phase, but not nearly as much as putrescine. We discuss how this comprehensive study may help to understand the involvement of polyamines in the control of cell proliferation.

Presence of constitutive endothelial nitric oxide synthase immunoreactivity in urothelial cells of hamster proximal urethra

Electrical field stimulation caused frequency-dependent relaxations in precontracted strips of hamster proximal urethra, which were attenuated by L-N(G)-nitroarginine methyl ester (10(-4) M) and completely blocked by tetrodotoxin (10(-6) M). Strips of hamster urethra devoid of urothelium showed reduced relaxant responses to electrical field stimulation which were abolished by L-N(G)-nitroarginine methyl ester (10(-4) M). Western blot analysis showed the presence of a constitutive endothelial nitric oxide synthase in the urothelial layer, suggesting that urothelium may release nitric oxide in response to electrical field stimulation and that this release is blocked by tetrodotoxin. It is suggested that the urothelium may contribute to relaxations of the smooth muscle of hamster urethra produced by nerve stimulation.

ATP and vasoactive intestinal polypeptide relaxant responses in hamster isolated proximal urethra

1. Nitric oxide (NO) is known from previous studies to be the principle transmitter in NANC inhibitory nerves supplying the hamster urethra. However, the identity of the cotransmitter(s) responsible for the responses remaining following block with L-NG-nitroarginine methyl ester (L-NAME) is not known. 2. Electrical field stimulation (EFS) of circular strips of hamster proximal urethra precontracted with arginine vasopressin (AVP 10(-8) M), and in the presence of phentolamine (10(-6) M), propranolol (10(-6) M) and atropine (10(-6) M), caused frequency-dependent relaxation, which was attenuated by suramin (10(-4) M) and reactive blue 2 (RB2; 2 x 10(-4) M), but not by pyridoxalphosphate-6-azophenyl-2',4'-disulphonic acid (PPADS; 10(-4) M), alpha-chymotrypsin (10-50 u ml(-1)) or by the vasoactive intestinal polypeptide (VIP) antagonist, [Lys1, Pro2,5, Arg3,4, Tyr6]-VIP, (5 x 10(-7)-10(-6) M). In the presence of indomethacin (10(-6) M) frequency-dependent relaxations to EFS were enhanced, particularly at the lower frequencies of stimulation. EFS-induced relaxation was blocked by tetrodotoxin (10(-6) M), indicating its neurogenic origin. 3. Exogenous ATP (10(-7)-10(-3) M) produced concentration-related relaxations which were attenuated by the P2-purinoceptor antagonists suramin (10(-4) M) and RB2 (2 x 10(-4) M) but not by PPADS (10(-4) M). ATP-induced relaxations were also reduced significantly by indomethacin (10(-6) M). The inhibitory responses to ATP were urothelium- and NO-independent, since they were not affected by either removal of urothelium or by L-NAME (10(-4) M). 4. Exogenous VIP (10(-9)-10(-7) M) induced concentration-related relaxations which were not affected by urothelium removal, L-NAME (10(-4) M), alpha-chymotrypsin (10-50 u ml(-1)) or by [Lys1, Pro2,5, Arg3,4, Tyr6]-VIP (3 x 10(-7)-10(-6) M). Nevertheless, suramin (10(-4) M) and RB2 (2 x 10(-4) M) but not PPADS (10(-4) M) antagonized the VIP-induced relaxant responses. Calcitonin gene-related peptide (CGRP: 10(-9)-10(-7) M) was devoid of any effect or only elicited a small relaxant response in AVP-precontracted strips. 5. Exogenous prostaglandin E2 (PGE2; 10(-9)-3 x 10(-6) M) and the NO donor, sodium nitroprusside (SNP; 10(-8)-3 x 10(-5) M) elicited concentration-related relaxations on the hamster proximal urethra which were not attenuated by suramin (10(-4) M), RB2 (2 x 10(-4) M), or by PPADS (10(-4) M), indicating a specific inhibitory effect of the antagonists used. 6. In summary, these results are consistent with the view that ATP is an inhibitory transmitter released from inhibitory nerves supplying the NANC relaxation of hamster proximal urethra. The relaxant effect of ATP is NO- and urothelium-independent. The present study did not demonstrate whether VIP is released from parasympathetic nerves during EFS, since both alpha-chymotrypsin and [Lys1, Pro2,5, Arg3,4, Tyr6]-VIP were ineffective on neurogenic responses.

Neurogenic and non-neurogenic responses in the urinary bladder of hibernating hamster

1. Purinergic and cholinergic components of parasympathetic neurotransmission and contractile responses to exogenous alpha,beta-methylene ATP, acetylcholine, substance K, substance P, calcitonin gene-related peptide, vasoactive intestinal polypeptide and capsaicin have been investigated in the urinary bladder of hibernating hamsters (4 weeks), cold exposed (4 weeks) and age-matched controls. 2. Electrical field stimulation (EFS) evoked increased frequency-dependent contractions in the detrusor strips from hibernating hamsters compared with those obtained from cold-exposed and age-matched animals. Tetrodotoxin (10(-6) M) completely blocked the frequency-dependent contractions in all groups. 3. The purinergic component of the parasympathetic neurotransmission was not affected in hibernating and cold-exposed animals while the cholinergic component was increased with respect to age-matched animals. The neurogenic response to EFS, still present after incubation with atropine (10(-6) M) and suramin (10(-4) M), was attenuated by indomethacin (10(-6) M) and blocked by tetrodotoxin (10(-6) M). 4. Exogenous administration of alpha,beta-methylene ATP elicited a significantly reduced contraction in strips from hibernating and cold-exposed hamsters relative to age-matched animals. The contractile response to exogenous acetylcholine was greater in the detrusors from hibernating hamsters than in cold-exposed and age-matched animals. Substance K elicited reduced contractions in preparations from hibernating animals compared with cold-exposed and control animals. Calcitonin gene-related peptide, vasoactive intestinal polypeptide, substance P and capsaicin did not elicit any relaxant or contractile response either at resting tone or in carbachol (5 x 10(-7) M)-precontracted tissues. 5. In summary, our findings indicate that 4 weeks of hibernation can significantly increase neurogenic responses in the hamster urinary bladder. This appears to be due to an increase in postjunctional responses to acetylcholine. In contrast, there was a decrease of the postjunctional responses to the parasympathetic cotransmitter ATP and also to the sensory-motor neurotransmitter substance K.

Age-related changes in purinergic and adrenergic components of sympathetic neurotransmission in guinea-pig seminal vesicles

1. Purinergic and adrenergic components of sympathetic neurotransmission and contractile responses to exogenous alpha,beta-methylene ATP and noradrenaline have been investigated in the seminal vesicles of 1-day (new-born), 2-weeks (young), 12-weeks (adult) and 2-years old (aged) guinea-pigs. 2. In seminal vesicles of new-born guinea-pigs electrical field stimulation (EFS; 80 V, 0.5 ms for 30 s, 2-32 Hz) evoked tonic frequency-related contractions. In 2-weeks old guinea-pigs the tonic contraction masked an initial phasic component of the neurogenic responses, whereas in 12-weeks and 2-years old guinea-pigs, neurogenic responses were biphasic, a phasic response being followed by a tonic contraction. In all experimental groups, prazosin (10(-6) M) blocked the tonic contraction while desensitization of P2X receptors by alpha,beta-methylene ATP (10(-4) M) abolished the phasic responses. 3. The phasic purinergic component of the neurogenic response was significantly higher in 12-weeks and 2-years old animals, compared with 2-weeks old guinea-pigs. At 32 Hz phasic contractions were (mN mg(-1) tissue): 0.047+/-0.012, 0.018+/-0.040 and 0.147+/-0.026 in 2-weeks, 12-weeks and 2-years old guinea-pigs, respectively. In contrast, the tonic adrenergic component of the neurogenic contraction significantly declined at 12-weeks and 2-years compared with 2-weeks old guinea-pigs. 4. Contractile responses (mN mg(-1) tissue) to the highest concentration of alpha,beta-methylene ATP tested were significantly higher in 2-weeks (0.248+/-0.022) than in 1-day old animals (0.113+/-0.012) and decreased in 12-weeks (0.163+/-0.016) and 2-years old guinea-pigs (0.200+/-0.008). The pD2 values for the purinoceptor agonist were also significantly lower in adult (4.74+/-0.20) and aged guinea-pigs (5.22+/-0.08) compared with 2-weeks old animals (5.91+/-0.27). Conversely, responses to the highest concentration of noradrenaline gradually decreased with age, without significant changes in the pD2 values. Contractile responses to KCl (240 mM) did not differ significantly between the experimental groups. 5. These results demonstrate age-related changes in purinergic and adrenergic components of sympathetic neurotransmission in the guinea-pig seminal vesicles. The purinergic component is absent in new-born animals and it appears fully developed in adult and old guinea-pigs, while the adrenergic component decreases with age. Pre- and postjunctional mechanisms contributing to the age-related changes of sympathetic neurotransmission are discussed.

Inhibitors of phosphoprotein phosphatases 1 and 2A cause activation of a 53 kDa protein kinase accompanying the apoptotic response of breast cancer cells

Treatment of MCF-7 breast cancer cells with 50 nM okadaic acid triggers an apoptotic response which is accompanied by a 7-fold increase in the activity of a protein kinase with a relative molecular mass of 53 kDa. The activity of the kinase was stimulated by cell treatment with inhibitors of phosphoprotein phosphatase 1 and 2A, but not by stressing conditions. Okadaic acid-induced stimulation of the 53 kDa protein kinase was not abolished by coincubation of cells with cycloheximide. We conclude that stimulation of the 53 kDa protein kinase by inhibitors of phosphoprotein phosphatases involves pre-existing molecular components whose activity depends on the phosphorylation state of serine/threonine residues.

A pharmacological and histochemical study of hamster urethra and the role of urothelium

1. Electrical field stimulation (EFS) of circular strips of hamster proximal urethra caused frequency-dependent relaxations at raised tone. Phentolamine (10(-6) M), propranolol (10(-6) M) and atropine (10(-6) M) were present throughout the experiment. Neurogenic relaxation was attenuated by L-NG-nitroarginine methyl ester (L-NAME) (10(-4) M), was restored by L-arginine (3 x 10(-3) M) but not by D-arginine (3 x 10(-3) M) and completely blocked by tetrodotoxin (10(-6) M). Neurogenic relaxation was also reduced by suramin (10(-4) M) and totally blocked by suramin together with L-NAME. Strips of hamster urethra devoid of urothelium showed little, if any, relaxant response to EFS. 2. An immunohistochemical study showed nitric oxide synthase-immunoreactive nerves in the smooth muscle layers and in the lamina propria, just beneath the urothelium, but no nitric oxide synthase (NOS) staining in the urothelial layer. 3. Noradrenaline elicited a significantly greater contraction in strips without urothelium than in control strips. L-NAME (10(-4) M) did not affect noradrenaline-induced contraction in both control and urothelium-free strips. The contractile response to acetylcholine was not dependent on the presence or absence of urothelium. Nevertheless the response induced by exogenous acetylcholine (10(-3) M) was increased by L-NAME (10(-4) M), both in intact and in urothelium-free strips. 4. Prostaglandin E2 (10(-8)-5 x 10(-6) M) and 2-methyl-thio-ATP (10(-9)-10(-5) M) relaxed proximal urethra. Suramin (10(-4) M) significantly inhibited the relaxation induced by 2-methyl-thio-ATP. The amplitude of these responses was not significantly different between intact and urothelium-free strips and was not blocked by L-NAME (10(-4) M). 5. These results suggest that nitric oxide (NO) is the principal transmitter involved in the non-adrenergic, non-cholinergic (NANC) relaxation of hamster proximal urethra possibly together with another inhibitory transmitter released from nerves. NO can be released from nerves located in the circular smooth muscle layer and in the lamina propria rather than in the urothelium. The reduced neurogenic relaxation in urothelium-free preparations suggests that a NO-dependent inhibitory factor is released from the urothelium. In addition, ATP and prostaglandin E2 may be involved, together with NO, in the urethra during micturition.

The biphasic response of rat vesical smooth muscle to ATP

1. Adenosine-5'-triphosphate (ATP) is known to exert a variety of biological effects via the activation of either ionotropic P2x- or G-protein coupled P2Y-purinoceptor subtypes. In this study the effects induced by ATP and ATP analogues on rat bladder strips were characterized at resting tone and in carbachol-prestimulated tissues. 2. ATP exerted a clear concentration-dependent biphasic response, which was maximal at 1 mM concentration and was characterized by an immediate and transient contraction, followed by a slower sustained relaxation. The receptor mediating contraction was susceptible to desensitization by ATP and by the ATP analogue, alpha,beta-methyleneATP (alpha,beta-meATP) showing the typical features of the P2x-purinoceptor; conversely, ATP-evoked relaxation did not undergo tachyphylaxis following either ATP or alpha,beta-meATP. 3. The slower and sustained relaxant phase seemed to be due to activation of P2Y-purinoceptors, based on responses obtained with the P2Y agonist, 2-methyl-thioATP (2-meSATP) and, more importantly, based on the clear involvement of the G-proteins. In fact, the G-protein activator, guanosine 5'-O-(3-thiotriphosphate) (GTP gamma S) significantly potentiated and the G-protein blocking agent, guanosine 5'-O-(2-thio-diphosphate) (GDP beta S) completely abolished the ATP-induced relaxation. No effects were exerted by these two G-protein modulators on the ATP-induced contraction. 4. The relaxant component of the ATP response of bladder tissue was not significantly influenced by nitro-benzyl-thioinosine (NBTI) or by 8-phenyltheophylline (8-PT), suggesting that the contribution of the ATP metabolite adenosine to this response was negligible. Moreover, relaxation evoked by ATP and by the adenosine analogue, 5'-N-ethylcarboxamidoadenosine (NECA) was additive.5. Suramin was unable to modify either the relaxant or the contractile responses of bladder strips to ATP. However, when tested on the concentration-response curve to the slowly hydrolysable P2x-agonist alpha,beta-meATP, a rightward shift was detected, suggesting that ATP contractile responses are mediated by suramine-sensitive P2x-purinoceptors.6. Uridine-5'-triphosphate (UTP) only induced a rapid and concentration-dependent contraction of the rat bladder preparation, which was not desensitized by pre-exposure to alpha,beta-meATP, suggesting that UTP responses were not mediated by the 'classical' P2X-purinoceptor.7. It is therefore concluded that both P2x- and P2y-purinoceptors, which mediate ATP-induced contraction and relaxation, respectively, are present in rat bladder. Moreover, removal of epithelium did not affect ATP-elicited contraction, whereas ATP-induced relaxation was significantly augmented. These data suggest that P2x- and P2Y- purinoceptors are localized in smooth muscle cells and that the relaxant response is probably modulated by excitatory factor(s) released by epithelial cells.

Effect of substance P and capsaicin on stomach fundus and ileum of streptozotocin-diabetic rats

The in vitro responses of longitudinal preparations of rat stomach fundus and ileum to capsaicin at 1, 8, 4, 16 and 26 weeks and to substance P at 1 and 8 weeks from diabetes induction were studied. The results were compared with those obtained in age-matched control rats. The contractile responses to exogenous substance P and capsaicin were not affected in the stomach fundus from diabetic rats. Atropine (1 microM) did not antagonize the substance P-induced response whereas it inhibited about 90% of the capsaicin-induced response in controls and about 60% of the response in diabetic rats. At the resting tone, capsaicin induced a relaxation followed by a contraction in stomach fundus of control rats. Only a contraction was evoked in diabetic rats. In carbachol (0.05-0.1 microM) pre-stimulated strips, a complete restoration of the biphasic response was obtained in the diabetic state. The contractile response elicited by exogenous substance P was not significantly increased in the ileum preparations from diabetic rats; nevertheless the EC50 value for substance P was reduced 8 weeks after the onset of diabetes. The response elicited by capsaicin in the ileum of control rats was also biphasic. The capsaicin-induced contraction was greater in tissue from diabetic rats as compared with controls and relaxation was not evident. An age-related decrease of the contraction was also evident in both groups. Atropine (1 microM) partially antagonized the responses to substance P and capsaicin. The inhibition of the responses with atropine was more evident in control than in diabetic rats. These results suggest that the myogenic actions of several agonists in these two tissues are differently modified in experimental diabetes.

Effect of substance P and capsaicin on urinary bladder of diabetic rats and the role of the epithelium

The in vitro responses of rat urinary bladder, to substance P and capsaicin were studied at 1, 4, 16, and 26 weeks of diabetes induction by streptozotocin. We also studied the role of epithelium in these responses. The results were compared with those obtained in age-matched control rats. The bladder contractile response to exogenous substance P was similar in both groups at all stages (1-26 weeks) studied, whereas the bladder response to capsaicin gradually decreased with the progression of diabetes. Atropine did not inhibit these responses whereas indomethacin slightly reduced substance P- but not capsaicin-induced responses in control and diabetic rats. The removal of epithelium slightly increased the substance P- and capsaicin-induced responses in control tissue; these responses were significantly reduced in tissue excised from diabetic rats. Our results indicate that, in rat urinary bladder, diabetes (1) provokes an impairment of capsaicin-sensitive sensory fibers but not of the cholinergic system even at an early stage (4 weeks) of the disease, (2) has no effect on the sensitivity of smooth muscle cells to substance P, (3) stimulates the release of epithelial contracting factors, partially non-prostanoic. Furthermore epithelium removal impairs acetylcholine-induced contraction in bladder excised from diabetic rats but not in controls.

A possible role for urinary bladder epithelium in bradykinin-induced contraction in diabetic rats

Diabetes provokes a greater responsiveness of rat urinary bladder preparations to bradykinin and a greater formation and release of prostaglandin F2 alpha, without affecting prostaglandin E2 release significantly. Inhibition of cyclooxygenase by indomethacin (1 microM) inhibits the contraction elicited by bradykinin and leads to identical contractile responses of control and diabetic urinary bladder strips. Removal of the urinary bladder epithelium does not modify the contractile response evoked by bradykinin in control preparations but significantly decreases the contraction of preparations of diabetic tissues. Quantitatively, the activity of control urinary bladder strips with epithelium and the activity of diabetic preparations without epithelium are the same. More prostaglandin F2 alpha is released into the medium by urinary bladder strips devoid of epithelium in both control and in diabetic rats. These results indicate a role for epithelial cells in the smooth muscle contraction evoked by bradykinin in diabetic rats.