Electron microscopic immunocytochemical detection of PSD-95, PSD-93, SAP-102, and SAP-97 at postsynaptic, presynaptic, and nonsynaptic sites of adult and neonatal rat visual cortex

Membrane-associated guanylate kinases (MAGUKs) assemble protein complexes at sites of cell-cell contact. At excitatory synapses in brain, MAGUKs localize to the postsynaptic density (PSD) and interact with N-methyl-D-aspartate (NMDA) glutamate receptors and downstream signaling proteins. However, NMDA receptors are not restricted to the PSDs, as electron microscopic immunocytochemical (EM-ICC) results indicate that NMDA receptors also occur at nonsynaptic portions of dendrites, perhaps functioning as reserves for rapid insertion into synaptic membranes in response to appropriate synaptic activity. NMDA receptors also occur in axons, at least in part to support glutamate-dependent enhancement of transmitter release. In this study, a systematic EM-ICC survey was performed to determine whether the distributions of four neuronal MAGUKs-PSD-95, PSD-93, SAP-102, and SAP-97-resemble that of NMDA receptors. Quantitative analysis revealed that the density of PSD-95 over thick PSDs of asymmetric axo-spinous synaptic junctions is 2-3-fold the level in the immediately adjacent cytoplasm of spines and terminals, while symmetric synapses show no association with PSD-95. Similarly, all four MAGUKs occur over PSDs of spines. However, we also detected MAGUK immunoreactivity, albeit more diffusely, along presynaptic membranes and in the cytoplasm of axons and dendritic shafts. In fact, the overall distribution of PSD-95 within the neuropil is equally prevalent along plasma membranes (including synaptic portions) as in the cytoplasm, away from plasma membranes. These results suggest that MAGUKs have dual roles: to maintain receptors at synapses and to regulate shuttling of receptors between nonsynaptic and synaptic sites.

Chronic Sildenafil Improves Erectile Function and Endothelium-dependent Cavernosal Relaxations in Rats: Lack of Tachyphylaxis

OBJECTIVES

Sildenafil is a widely-prescribed effective on-demand treatment of erectile dysfunction (ED). Chronic treatment with sildenafil could help patients with ED.

METHODS

The effects of an 8-week long treatment with sildenafil (60 mg/kg/d sc) in male Sprague Dawley rats were evaluated on electrically-elicited erectile responses in vivo before and after an acute injection of sildenafil (0.3mg/kg iv). In addition, endothelium-dependent and -independent relaxations of strips of corpus cavernosum in vitro were examined. All experiments were performed 36 hours after the last injection of sildenafil.

RESULTS

Endothelium-dependent relaxations of cavernosal strips to acetylcholine were enhanced after chronic treatment with sildenafil while relaxations to A23187 or sodium nitroprusside were unchanged. Frequency-dependent erectile responses elicited by cavernous nerve stimulation were significantly improved. Moreover, the erectile responses to acute sildenafil were greater in chronically-treated rats with sildenafil.

CONCLUSIONS

This is the first report providing experimental support for chronic dosing with sildenafil which could be of use for patients that are poor responders to on-demand treatment. Chronic sildenafil may regulate the transduction pathway leading to the activation of eNOS but has no effect on NO bioavailability or on the cGMP pathway, thereby eliminating a possible concern for tachyphylaxis.

Vaginal physiological changes in a model of sexual arousal in anesthetized rats

The understanding of the pathophysiology of female sexual dysfunction suffers from the lack of a convenient model for the study of female genital sexual response. In this study, systemic arterial blood pressure (BP) as well as partial oxygen tension, temperature, and blood engorgement of the vagina [using laser-Doppler flowmetry in arbitrary units (AU)] were measured in anesthetized, ovariectomized (1 wk before the start of the experiment) female rats. Vaginal sexual arousal was replicated by electrical stimulation of the pelvic nerve (PNS). PNS induced reproducible increases in the different vaginal parameters (from baseline value, respectively: 16 +/- 10 to 30 +/- 12 mmHg; 34.9 +/- 0.6 to 36 +/- 0.6 degrees C; 450 +/- 196 to 1,500 +/- 360 AU; P < 0.05, paired t-test) and BP (90 +/- 7 to 123 +/- 13 mmHg, P < 0.05, paired t-test). Vaginal vascular resistance was significantly decreased during PNS (from 0.23 +/- 0.15 to 0.08 +/- 0.02 mmHg/AU). Vaginal wall tension was also measured with a force transducer. PNS induced an increase in vaginal wall tension (1.0 +/- 0.2 g), followed by a decrease under the prestimulation value. Intravenous atropine sulfate (1 mg/kg) injection abolished the increase in vaginal wall tension without significantly affecting vaginal vascular resistance. Intravenous vercuronium bromide (2 mg/kg) injection abolished the decrease in vaginal wall tension. Concomitant electrical stimulation of the paravertebral sympathetic chain inhibited vaginal response induced by PNS. Electrical stimulation of the medial preoptic area of the hypothalamus induced a response qualitatively equivalent to PNS with a significant decrease of vaginal vascular resistance. These data support that vaginal contractions involve both smooth and striated muscles and indicate that neural control of vaginal sexual arousal have great similarities in male and female rats.

Insertion of a double pigtail ureteral stent for the prevention of urological complications in renal transplantation: a prospective randomized study

PURPOSE

Urologists successfully use ureteral stents to protect the ureterovesical anastomosis in nontransplant patients.

MATERIALS AND METHODS

We determined the value of ureteral stents in transplant patients. The frequency of urological complications (leaks, obstructions and urinary tract infections) was compared in a prospective randomized series of 194 kidney transplantations (97 with and 97 without a double pigtail ureteral stent).

RESULTS

In the stent group 1 patient had a urinary leak and 35 had urinary tract infections (including 2 cases of Corynebacterium cystitis). In the no stent group 6 patients had urinary leaks, 4 had obstructions and 32 had urinary tract infections. The 1-year patient and graft survival rates were similar in both groups, and renal function at 1 year was also similar (229 versus 208 mumol./l. creatinine in the stent and no stent groups, respectively). A small number of stent related complications occurred (2 stent breakages and 1 stent migration). No stones formed in any case.

CONCLUSIONS

Ureteral stent insertion significantly decreases the rate of vesicoureteral leakage and obstruction in renal transplantation.

Signalling pathways involved in sildenafil-induced relaxation of human bladder dome smooth muscle

BACKGROUND AND PURPOSE

The mechanism(s) of action responsible for the beneficial effects of phosphodiesterase 5 (PDE5) inhibitors including sildenafil on lower urinary tract symptoms suggestive of benign prostate hyperplasia are unclear. In particular, the role of the NO-cGMP signalling pathway in regulating human bladder dome smooth muscle relaxation is questionable. Thus, we assessed the ability of a PDE5 inhibitor, sildenafil, to relax such tissue, and identified the signalling pathways involved in this relaxation.

EXPERIMENTAL APPROACH

Human bladder samples were obtained from 20 patients with no overactive bladder undergoing cystectomy for bladder cancer. Detrusor strips were mounted isometrically in Krebs-HEPES solution. Concentration-response curves for sildenafil (10 nM-30 microM) were generated in the presence of various inhibitors on carbachol-induced pre-contraction.

KEY RESULTS

Sildenafil relaxed carbachol-pre-contracted human detrusor strips, starting at 3 microM. This effect was not modified by NO donors, S-nitroso-N-acetylpenicillamine (10 microM) or sodium nitroprusside (300 nM), but was significantly inhibited by inhibition of guanylate cyclase (with ODQ, 10 microM) or adenylyl cyclase (with MDL-12,330A, 10 microM), by the ATP-sensitive potassium channel inhibitor, glibenclamide (10 microM), or inhibition of the large (with iberiotoxin, 30 nM) or small (with apamin, 100 nM) conductance calcium-activated potassium channels.

CONCLUSIONS AND IMPLICATIONS

Sildenafil-induced relaxation of human detrusor smooth muscle involved cGMP-, cAMP- and K(+) channel-dependent signalling pathways, with a minor contribution from NO. The effect of this sildenafil-induced relaxation on the clinical benefit of PDE5 inhibitors on urinary storage symptoms in men deserves further investigation.

Erectile dysfunction in spontaneously hypertensive rats: pathophysiological mechanisms

Hypertensive men have a higher prevalence of erectile dysfunction (ED) than the general population. Experimental evidence of ED in hypertensive animals is scarce. This study evaluates the erectile function of spontaneously hypertensive rats (SHR) and age-matched normotensive Wistar-Kyoto rats (WKY) in vivo by the increase in intracavernosal pressure after electrical stimulation of the cavernous nerve (CN) and by isometric tension studies on corporal strips. Frequency-dependent erectile responses to CN stimulations were reduced in SHR. Phenylephrine induced lower corporal contractions in SHR although pD2 values were similar to WKY. Endothelium-dependent relaxations to ACh were impaired significantly in SHR, and indomethacin improved these relaxations in both WKY and SHR, the latter thus reaching values similar to WKY. Corporal relaxations to sodium nitroprusside were enhanced in SHR. Thus a dysfunctional alpha-adrenergic contraction of the corporal smooth muscle, an increased cyclooxygenase-dependent constrictor tone, and/or a defect in endothelium-dependent reactivity are associated with the altered erectile mechanisms in SHR. Drugs targeting endothelial dysfunction may delay the occurrence of ED as a complication of hypertension.

Erectile dysfunction: an early marker for hypertension? A longitudinal study in spontaneously hypertensive rats

Erectile dysfunction (ED) is another manifestation of vascular disease. We evaluated the natural history of ED in the spontaneously hypertensive rat (SHR) and the respective participation of associated pathophysiological modifications, i.e., endothelial dysfunction and tissue remodeling. SHR and their normotensive counterparts [Wistar-Kyoto rats (WKY)] of 6, 12, and 24 wk of age (n = 12) were used to evaluate erectile function, erectile and aortic tissue reactivity, and remodeling. Erectile responses in SHR are reduced at all ages (P < 0.001). In both aortic and erectile tissues of SHR and WKY, relaxations to ACh are altered progressively with age, although more markedly in SHR. They are decreased at 12 wk of age in erectile tissue of SHR compared with WKY (maximal relaxation: -19.2 +/- 2.8% vs. -28.3 +/- 3.9%, P < 0.001) but only at 24 wk of age in aortas (-47.9 +/- 6.4% vs. -90.5 +/- 2.9%, P < 0.001). Relaxations to sodium nitroprusside are unaltered in aortic rings of both strains but enhanced in erectile tissue of SHR at 12 wk of age. Major modifications in the distribution of collagen I, III, and V in SHR occur in both types of tissue and are detectable sooner in erectile tissue compared with aortic tissue. The onset of ED is detectable before the onset of hypertension in the SHR. Structural and functional alterations, while similar, occur earlier in erectile compared with vascular tissue. If confirmed in humans, ED could be an early warning sign for hypertension, and common therapeutic strategies targeting both ED and hypertension could be investigated.

Assessment of erectogenic properties of apomorphine and yohimbine in man

1. In a four period, double-blind, placebo-controlled study, apomorphine (0.009 mg kg-1 subcutaneous route) and yohimbine (0.30 mg kg-1 i.v. route) were administered to 10 male healthy volunteers. Penile circumference was monitored using plethysmography and subjective sexual arousal was self-assessed. Data were collected before, during and after a stimulation session during which 50 erotic slides were projected to the subjects. 2. Apomorphine induced an erection starting from the fourth minute post-injection, and potentiated the visually-induced response. Self assessment showed increased tumescence and rigidity without modifications of sexual arousal. 3. Yohimbine did not modify penile diameter without stimulation and did not affect the physiological response to erotic stimuli. 'Sexual excitement' was decreased by yohimbine during the post-stimulation phase. One subject experienced severe anxiety while he was infused with yohimbine. 4. These results are discussed with reference to animal data and to recent studies carried out in impotent patients.

Effects of potassium channel modulators on human detrusor smooth muscle myogenic phasic contractile activity: potential therapeutic targets for overactive bladder

OBJECTIVES

Increased urinary bladder detrusor smooth muscle phasic contractility has been suggested to be associated with idiopathic bladder overactivity (OAB). We examined the role of voltage-dependent L-type calcium channels, adenosine triphosphate-sensitive potassium (K(ATP)) channels, and calcium-activated potassium (BK(Ca) and SK(Ca)) channels in the regulation of human detrusor phasic contractile activity.

METHODS

Isolated human bladder strip phasic contractions were measured and quantified as the mean area under the force-time curve, amplitude, and frequency of phasic contractions in 22 bladder samples.

RESULTS

Human detrusor strips displayed myogenic phasic contractions in the presence of atropine (10(-6) M), phentolamine (10(-6) M), propranolol (10(-6) M), suramin (10(-5) M), and tetrodotoxin (10(-6) M). The L-type calcium channel inhibitor nifedipine (300 nM) abolished the contractile activity. Blockade of K(ATP) channels by glibenclamide (1 and 10 microM) did not alter myogenic contractions. In contrast, the K(ATP) channel opener pinacidil (10 microM) markedly inhibited phasic contractility. Iberiotoxin (100 nM) and apamin (100 nM), potent and selective inhibitors of BK(Ca) and SK(Ca) channels, respectively, significantly increased the area under the force-time curve and the amplitude of contractions.

CONCLUSIONS

Phasic contractions of human detrusor are dependent on calcium entry through L-type calcium channels. BK(Ca) and SK(Ca) channels play a key role in the modulation of human detrusor smooth muscle phasic contractility. Furthermore, these observations support the concept that increasing conductance through K(ATP), BK(Ca), and SK(Ca) channels may represent attractive pharmacologic targets for decreasing phasic contractions of detrusor smooth muscle in OAB.

A comparison of the effects of tamsulosin and alfuzosin on neurally evoked increases in bladder neck and seminal vesicle pressure in rats

OBJECTIVE

To assess the effects of the alpha 1-adrenoceptor antagonists alfuzosin and tamsulosin on the physiological events associated with ejaculation in the rat, because when these drugs are used for treating symptomatic benign prostatic hyperplasia in men they may affect ejaculation by impairing bladder neck closure and seminal vesicle contraction.

MATERIALS AND METHODS

In clinical trials the incidence of ejaculatory disorders in men is typically < 1% with alfuzosin and 4-18% with tamsulosin. The effects of tamsulosin and alfuzosin on bladder neck and seminal vesicle pressures (BNP and SVP) in the rat were analysed. Increases in BNP and SVP were induced in urethane-anaesthetized. Wistar rats by electrical stimulation (ES) of the hypogastric nerve (HN) before and after an intravenous injection with vehicle, 3 or 10 micrograms/kg of tamsulosin or alfuzosin (10 rats/group). The mean amplitude and area under the curve (AUC) of the BNP and SVP were expressed as the percentage of the response to ES of HN before the treatment.

RESULTS

The amplitude and AUC of the SVP were significantly decreased by both doses of tamsulosin, and marginally decreased by the same doses of alfuzosin. The amplitude of the BNP was significantly decreased by 3 and 10 micrograms/kg of tamsulosin and 10 micrograms/kg alfuzosin, and marginally decreased by 3 micrograms/kg alfuzosin. The AUC of the BNP was significantly decreased by both doses of tamsulosin, but barely affected by alfuzosin at the same doses.

CONCLUSION

Over the doses assessed, alfuzosin had significantly less deleterious effect on increases in BNP and SVP induced by ES of the HN than had tamsulosin.

Brain oxytocin receptors mediate ejaculation elicited by 7-hydroxy-2-(di-N-propylamino) tetralin (7-OH-DPAT) in anaesthetized rats

BACKGROUND AND PURPOSE

The involvement of the neuropeptide oxytocin in the control of male sexual responses is documented although its exact mechanisms of action, and especially the site(s) of action, are not fully delineated. In order to clarify this issue, we tested the effects of a peptide oxytocin antagonist delivered through different routes on sexual responses elicited, in anaesthetized male rats, by i.c.v. 7-hydroxy-2-(di-N-propylamino) tetralin (7-OH-DPAT), a dopamine agonist, preferentially active on D3 receptors.

EXPERIMENTAL APPROACH

Seminal vesicle pressure (SVP) and bulbospongiosus muscle (BS) electromyograms were recorded as physiological markers of emission and expulsion phases of ejaculation respectively and intracavernosal pressure (ICP) was monitored as a physiological marker of erection.

KEY RESULTS

When injected i.v., the oxytocin antagonist did not impair 7-OH-DPAT-induced SVP and ICP responses while BS burst frequency was diminished. When delivered i.c.v., the oxytocin antagonist dose-dependently inhibited occurrence of 7-OH-DPAT-induced sexual responses. When delivered intrathecally (i.t.) at the level of the 6th lumbar (L6) segment, but not the 13th thoracic (T13) segment, the oxytocin antagonist reduced the duration of BS responses and the occurrence of ejaculation without impairing ICP responses.

CONCLUSIONS AND IMPLICATIONS

Brain oxytocin receptors mediate male sexual responses elicited by i.c.v. 7-OH-DPAT in anaesthetized rats whereas L6 spinal oxytocin receptors only impair the occurrence of ejaculation. Peripheral oxytocin receptors are marginally involved in 7-OH-DPAT-induced sexual responses. These findings should be considered for the development of potential pharmacological treatment of premature ejaculation in man.

Bioelectrical impedance analysis (BIA)-derived phase angle (PA) is a practical aid to nutritional assessment in hospital in-patients

BACKGROUND

Nutritional status can be difficult to assess. Bioelectrical impedance analysis (BIA)-derived phase angle (PA), and the plasma markers citrulline and transthyretin (pre-albumin) have the potential to assist, but the protocol of fasting and resting for BIA renders the investigation impractical for routine use, especially so in populations at high risk of malnutrition.

AIMS

1 To clarify whether starving and resting are necessary for reliable measurement of PA. 2 To identify whether PA, citrulline and transthyretin correlate with nutritional status.

METHODS

Eighty consenting adult in-patients were recruited. Nutritional status was determined by subjective global assessment (SGA) used as gold standard. The Malnutrition Universal Screening Tool (MUST) was used and anthropometric measurements were performed. Serum was analysed for citrulline and transthyretin. PA was measured using Bodystat 4000. The PA was considered to define malnutrition when lower than reference ranges for sex and age, and severe malnutrition if more than 2 integers below the lower limit. Anthropometric measurements were categorised according to WHO reference centiles. Ordinal logistic regression estimated the strength of association of PA, citrulline and transthyretin with SGA. PA values in the different metabolic states were compared using paired t tests.

RESULTS

All 80 subjects completed the BIA and the nutritional assessments in the 3 different states; 14 declined to provide blood samples for the biochemical assays. Malnutrition was identified in 32 cases, severe malnutrition in 14 cases, the remaining 34 cases were deemed not to be malnourished. PA was strongly inversely associated with SGA (Odds Ratio [OR] per unit increase = 0.21, CI 0.12-0.37, p < 0.001). PA was not influenced by exercise (p = 0.134) or food intake (p = 0.184). Transthyretin was inversely associated with malnourished/severely malnourished states (OR = 0.98, 95% CI 0.97-0.99, p = 0.001), but had poorer predictive values than PA. There was no significant association between citrulline concentration and SGA (OR = 1.01, 95% CI 0.99-1.04, p = 0.348).

CONCLUSIONS

The BIA-derived PA reliably identifies malnutrition. It is strongly associated with SGA but requires less skill and experience, and out-performs circulating transthyretin, rendering it a promising and less operator-dependent tool for assessing nutritional status in hospital patients. Our novel demonstration that fasting and bed-rest are unnecessary consolidates that position.

Vardenafil decreases bladder afferent nerve activity in unanesthetized, decerebrate, spinal cord-injured rats

BACKGROUND

Phosphodiesterase type 5 inhibitors (PDE5-Is) improve storage symptoms in benign prostatic hyperplasia patients, despite a lack of effect on peak urinary flow rate. Moreover, vardenafil improves urodynamic parameters in spinal cord-injured (SCI) patients with neurogenic detrusor overactivity (NDO). SCI rats also display NDO characterized by nonvoiding contractions (NVCs) during bladder filling, resulting in an increased bladder afferent nerve firing (BANF).

OBJECTIVE

We postulated that vardenafil could improve urodynamic parameters by reducing BANF. The effect of vardenafil has been investigated on intravesical pressure by cystometry experiments while recording BANF in response to bladder filling.

DESIGN, SETTING, AND PARTICIPANTS

Complete T7-T8 spinalization was performed in 15 female adult Sprague-Dawley rats (250-275 g).

MEASUREMENTS

At 21-29 d postspinalization, fine filaments were dissected from the L6 dorsal roots and placed across a bipolar electrode. Bladder afferent nerve fibers were identified by electrical stimulation of the pelvic nerve and bladder distension. SCI rats were decerebrated before cystometry experiments. Bladders were filled to determine the maximal bladder filling volume (BFV) for each rat. Then, after bladder stabilization at 75% of maximal BFV, saline (n=7) or vardenafil 1 mg/kg (n=8) was delivered intravenously. NVCs and BANF were recorded for 45 min.

RESULTS AND LIMITATIONS

In all SCI rats, BANF was already present and regular at resting conditions (26.2±4.1 spikes per second). During bladder filling, intravesical pressure (IVP) slowly increased with transient NVCs superimposed. Concomitantly, BANF progressively increased up to 2.4-fold at maximal BFV (2.08±0.24 ml). After stabilization at submaximal BFV, BANF was increased by 186±37%. Vardenafil injection induced an immediate decrease in NVCs compared to saline (p<0.001) and BANF (52% decrease vs 28% in saline after 45 min; p<0.001).

CONCLUSIONS

Systemic vardenafil reduced both NVCs and BANF in unanesthetized, decerebrate, SCI rats. These findings provide new insights into the mechanism of action by which PDE5-Is improve storage symptoms in SCI patients.

D2-like receptors mediate the expulsion phase of ejaculation elicited by 8-hydroxy-2-(di-N-propylamino)tetralin in rats

The mechanism of action by which 8-hydroxy-2-(di-N-propylamino)tetralin (8-OH-DPAT) facilitates ejaculation in conscious rats is not clearly established. The serotonin (5-HT) 1A agonist 8-OH-DPAT may actually act on cerebral dopaminergic receptors to exert its proejaculatory effect. The present work was undertaken to clarify this issue by testing various compounds i.c.v. delivered in an experimental model of the expulsion phase of ejaculation in anesthetized Wistar rats. Intracerebroventricular delivery of 8-OH-DPAT dose-dependently (ED(50) = 17 microg) induced rhythmic contractions of bulbospongiosus (BS) muscles, which are of paramount importance for the expulsion of semen, occurring in the form of cluster of bursts evidenced by the recording of BS muscle electrical activity. The 5-HT1A antagonist WAY100635 (N-[2-[4-(2-methoxyphenyl)-1-piperazinyl]ethyl]-N-2-pyridinylcyclohexanecarboxamide) (20 microg) i.c.v. coadministered with 8-OH-DPAT (20 microg) was unable to inhibit the effect of 8-OH-DPAT on BS muscle contractile activity. Conversely, raclopride (40 microg) and spiperone (10 microg), both dopamine D2-like receptor antagonists, i.c.v. coinjected with 8-OH-DPAT (20 microg), abolished BS muscle contractions. The involvement of D2-like receptors was further supported by the fact that the D2-like agonist quinelorane (20 microg i.c.v.) also induced BS muscle rhythmic contractions. Our data demonstrate that D2-like receptors mediate the induction by 8-OH-DPAT of rhythmic BS muscle contractions and suggest that i.c.v. delivery of D2-like receptor agonists to anesthetized rats represents a relevant experimental model to study the expulsion phase of ejaculation.

Inhibition of ejaculation by the non-peptide oxytocin receptor antagonist GSK557296: a multi-level site of action

BACKGROUND AND PURPOSE

Oxytocin (OT) plays a major role in the control of male sexual responses. Notably, blockade of OT receptors has been reported to inhibit ejaculation in animals. The study aimed to investigate the action of a highly selective, non-peptide OT antagonist GSK557296 in a model of pharmacologically induced ejaculation in anaesthetized rats. The site of action was assessed by investigating different delivery routes for this compound.

EXPERIMENTAL APPROACH

Urethane-anaesthetized Wistar rats were implanted with a cerebral ventricle cannula for i.c.v. injections or with a subdural catheter for intrathecal (i.t.) GSK557296 injections. Occurrence of ejaculation was assessed following i.v. 7-hydroxy-2-(di-N-propylamino)tetralin (7-OH-DPAT), a dopamine D3 receptor agonist. In addition, seminal vesicle pressures (SVP) and bulbospongiosus muscle (BS) EMG were recorded as physiological markers of emission and expulsion phases of ejaculation respectively.

KEY RESULTS

Highest i.v. GSK557296 dose reduced occurrence of ejaculation and increases in SVP but had no effect on BS-EMG. I.c.v. GSK557296 dose dependently inhibited ejaculation, increases in SVP and BS contractions. At spinal thoracic level, GSK557296 dose dependently inhibited ejaculation and increases in SVP but BS-EMG was impaired only with the highest dose. When delivered at lumbar level, GSK557296 dose dependently inhibited ejaculation, increases in SVP and BS contractions.

CONCLUSIONS AND IMPLICATIONS

In the 7-OH-DPAT-induced ejaculation model, GSK557296 acts peripherally and centrally to inhibit ejaculation with different modalities. Blockade of brain OT receptors seems to be the most effective mechanism of action. Targeting central OT receptors with highly selective antagonist seems a promising approach for the treatment of premature ejaculation.

Relaxation of phasic contractile activity of human detrusor strips by cyclic nucleotide phosphodiesterase type 4 inhibition

OBJECTIVES

Detrusor smooth muscle relaxation is mainly mediated by the cyclic adenosine monophosphate (cAMP) pathway. Elevation of cAMP levels by phosphodiesterase type 4 (PDE4) inhibition relaxes smooth muscles of various origins. We aimed to determine the effect of a PDE4 inhibitor, rolipram, on human detrusor contractions.

METHODS

Human bladder strips (from 20 different donors) with no known overactive bladder (OAB) were studied in organ baths. Detrusor samples with or without urothelium were incubated with carbachol 10(-6)mol/l (in presence or absence of forskolin, 3.10(-7)mol/l) or with KCl 10mmol/l to enhance phasic contractile activity. Concentration response curves for rolipram or vehicle were then performed.

RESULTS

Rolipram (10(-9) to 3.10(-5)mol/l) induced a moderate relaxing effect on carbachol-induced contractions. This effect was enhanced when cAMP levels were increased by forskolin (the maximal effect was 53.0+/-5.1 vs. 83.1+/-5.7%, p<0.01) or in strips with urothelium. In contrast, rolipram (10(-9) to 10(-4)mol/l) drastically inhibited phasic contractile activity: The developed tension, the area under the curve, and the amplitude of phasic activity were reduced to 64.8+/-3.6, 91.2+/-5.3, and 82.3+/-7.3%, respectively, versus 23.6+/-9.5, 34.7+/-18.8, and 18.0+/-16.2% for vehicle, respectively (p<0.05). Frequency of phasic activity was 0.96+/-0.45 contractions per minute versus 2.6+/-0.18 for vehicle (p<0.001). In strips with urothelium, the inhibitory effect of rolipram on phasic contractile activity was similar.

CONCLUSIONS

PDE4 isoenzymes are strongly involved in the regulation of phasic myogenic activity of human bladder strips. Because an increase of this phasic activity may play a role in the pathophysiology of detrusor overactivity, PDE4 inhibitors might represent an attractive strategy for the treatment of OAB.

Percutaneous antegrade dilation of ureteral strictures in kidney transplants

Transplant ureteral stricture can be treated by either incisional surgery or percutaneous endoluminal dilation. We present 17 cases of percutaneous antegrade endoluminal dilation. The results of this procedure were satisfactory, with a 70% success rate that seems to be maintained during long-term followup. The results were better if dilation was done on a short and recent juxta-anastomotic stricture stented with a 10F Double-J* catheter for 2 months.

Skin autofluorescence predicts major adverse cardiovascular events in patients with type 1 diabetes: a 7-year follow-up study

Background

Advanced glycation end-products play a role in diabetic vascular complications. Their optical properties allow to estimate their accumulation in tissues by measuring the skin autofluorescence (SAF). We searched for an association between SAF and major adverse cardiovascular events (MACE) incidence in subjects with Type 1 Diabetes (T1D) during a 7 year follow-up.

Methods

During year 2009, 232 subjects with T1D were included. SAF measurement, clinical [age, sex, body mass index (BMI), comorbidities] and biological data (HbA1C, blood lipids, renal parameters) were recorded. MACE (myocardial infarction, stroke, lower extremity amputation or a revascularization procedure) were registered at visits in the center or by phone call to general practitioners until 2016.

Results

The participants were mainly men (59.5%), 51.5 ± 16.7 years old, with BMI 25.0 ± 4.1 kg/m², diabetes duration 21.5 ± 13.6 years, HbA1C 7.6 ± 1.1%. LDL cholesterol was 1.04 ± 0.29 g/L, estimated Glomerular Filtration Rates (CKD-EPI): 86.3 ± 26.6 ml/min/1.73 m². Among these subjects, 25.1% were smokers, 45.3% had arterial hypertension, 15.9% had elevated AER (≥ 30 mg/24 h), and 9.9% subjects had a history of previous MACE. From 2009 to 2016, 22 patients had at least one new MACE: 6 myocardial infarctions, 1 lower limb amputation, 15 revascularization procedures. Their SAF was 2.63 ± 0.73 arbitrary units (AU) vs 2.08 ± 0.54 for other patients (p = 0.002). Using Cox-model, after adjustment for age (as the scale time), sex, diabetes duration, BMI, hypertension, smoking status, albumin excretion rates, statin treatment and a previous history of MACE, higher baseline levels of SAF were significantly associated with an increased risk of MACE during follow-up (HR = 4.13 [1.30–13.07]; p = 0.02 for 1 AU of SAF) and Kaplan–Meier curve follow-up showed significantly more frequent MACE in group with SAF upper the median (p = 0.001).

Conclusion

A high SAF predicts MACE in patients with T1D.

Electronic supplementary material

The online version of this article (10.1186/s12933-018-0718-8) contains supplementary material, which is available to authorized users.

ORIGINAL RESEARCH—BASIC SCIENCE: Erectile Dysfunction in Hypercholesterolemic Atherosclerotic Apolipoprotein E Knockout Mice

INTRODUCTION

Erectile dysfunction (ED) and cardiovascular diseases share the same risk factors. Although the use of hypercholesterolemic rabbit models has proven to be useful to illustrate the link between ED and hypercholesterolemia, the cost of daily maintenance of the animals and necessity for important amounts of drug have limited their use.

AIM

We aimed to develop a new model of atherosclerosis-associated ED in a well-known experimental model of atherosclerosis, the apolipoprotein E knockout (ApoE KO) mouse.

METHODS

Erectile function was evaluated by recording frequency-dependent increases in intracavernous pressure following electrical stimulation of the cavernous nerve in 26-, 32-, and 38-week-old ApoE KO mice fed a Western-type diet and age-matched C57BL6/J anesthetized mice. Atherosclerotic lesions were evaluated by planimetry in oil red O-stained aortas.

RESULTS

We found that in contrast to C57BL6/J mice, ApoE mice displayed atherosclerotic lesions covering 22% of the aortic luminal surface at 26 weeks of age and increasing to 27% and 35% at 32 weeks and 38 weeks of age, respectively. The amplitude of erectile responses to electrical stimulation of the cavernous nerve was markedly impaired in 26-week-old ApoE KO mice as compared with age-matched C57BL6/J mice. Impairment in erectile function persisted in ApoE KO mice 32 and 38 weeks of age.

CONCLUSIONS

The ApoE KO mouse, a well-characterized model to study disorders associated with hypercholesterolemia and atherosclerosis in cardiovascular research, could therefore be suitable for investigation of disease-modifying effects of new therapeutic strategies aiming to target both atherosclerosis and ED.

Spinal proerectile effect of apomorphine in the anesthetized rat

Considering the presence of dopaminergic receptors in the lumbosacral spinal cord, we tested whether apomorphine could exert a proerectile effect by acting at the spinal level. Intracavernous (ICP) and blood pressures (BP) were measured in anesthetized rats. ICP rises were quantified (duration, percentage of ICPmaximum/meanBP (ICPmax/BPx100), area under ICP curve (AUC/BP) and sum of AUC/BP after intravenous (i.v.) and intrathecal (i.t.) injections of apomorphine alone or in presence of i.t. oxytocin (10 ng). Both 10 and 30 microg i.v. apomorphine dosings elicited erectile events evidenced by ICP rises. Upon the 30 microg i.v. injection, duration of ICP rises were increased from 25+/-10 to 69+/-18 s (P<0.001), ICPmax/BPx100 from 21+/-3 to 50+/-14% (P=0.001), AUC/BP from 3+/-1 to 14+/-6 s (P=0.002) and sum of AUC/BP from 5+/-7 to 34+/-35 s (P=0.021). Upon 30 microg i.t. injections of apomorphine at the lumbosacral level, the number of ICP rises was increased from 0.2+/-0.4 to 3.0+/-1.5, ICPmax/BPx100 from 16+/-9 to 43+/-12 and sum of AUC/BP from 1+/-3 to 31+/-15 s compared to vehicle injection (P<0.05 for all parameters). Injection of 30 microg i.v. or i.t. apomorphine non-significantly enhanced the number and amplitude of the ICP rises induced by 10 ng i.t. oxytocin. However, the enhancement of the amplitude of the ICP rises elicited by i.t. oxytocin was more pronounced with i.t. apomorphine than with i.v. apomorphine. These results suggest the existence of a spinal site of action for apomorphine which may (1) participate to generation of erection and (2) exerts a facilitator effect on erection of supraspinal origin.

Combination of BAY 60-4552 and vardenafil exerts proerectile facilitator effects in rats with cavernous nerve injury: a proof of concept study for the treatment of phosphodiesterase type 5 inhibitor failure

BACKGROUND

Radical prostatectomy (RP) is frequently responsible for erectile dysfunction (ED). Post-RP patients often show a failure to respond to phosphodiesterase type 5 (PDE5) inhibitors.

OBJECTIVE

The acute effect of BAY 60-4552, the soluble guanylate cyclase (sGC) stimulator, and vardenafil were evaluated alone or in combination on erectile responses to electrical stimulation of the cavernous nerve (ES CN) in rats with cavernous nerve (CN) crush injury-induced ED.

DESIGN, SETTING, AND PARTICIPANTS

Male adult Sprague-Dawley rats underwent laparotomy (sham, n=10) or bilateral CN crush injury (n=56). After 3 wk of recovery, erectile function was evaluated under urethane anaesthesia following ES CN at different frequencies.

MEASUREMENTS

The acute effects of intravenous (IV) injection of vehicle, vardenafil 0.03 mg/kg, BAY 60-4552 0.03 mg/kg or 0.3 mg/kg, or a BAY 60-4552 0.03 mg/kg plus vardenafil 0.03 mg/kg combination were evaluated in CN-crushed rats.

RESULTS AND LIMITATIONS

Bilateral CN crush injury followed by a 3-wk recovery period decreased erectile responses to ES CN by about 50%. In CN-crushed rats, IV vardenafil 0.03 mg/kg and BAY 60-4552 (0.03 or 0.3 mg/kg) increased erectile responses to ES CN to the same extent: Δ intracavernosal pressure/mean arterial pressure (ICP/MAP) at 10 Hz ES CN was 21±1% after vehicle, 25±3% (p<0.001) after vardenafil, and 26±5% and 27±5% after BAY 60-4552 0.03 mg/kg (p<0.01) and 0.3 mg/kg (p<0.001), respectively. The combination of vardenafil with BAY 60-4552 in CN-crushed rats totally restored erectile responses to ES CN equivalent to sham rats (ΔICP/MAP at 10 Hz ES CN: 34±4% after BAY 60-4552/vardenafil combination vs 39±4% in sham rats; not significant).

CONCLUSIONS

The present study supports the concept that the combined administration of a sGC stimulator, BAY 60-4552, and vardenafil provides synergistic beneficial effects and might therefore salvage patients who experience treatment failures with PDE5 inhibitors after RP.