Combination therapy of testosterone enanthate and tadalafil on PDE5 inhibitor non-reponders with severe and intermediate testosterone deficiency.

Several studies have suggested combination therapy with testosterone supplementation in patients not responding to PDE5 inhibitors. Considering the pathophysiological basis for testosterone supplementation, the present study aims to identify whether combination therapy allows persistence of treatment effect after testosterone discontinuation. Furthermore, we evaluated whether the degree of testosterone depletion affects treatment outcome from combination therapy. Hypogonadal patients (<350 ng dl(-1)) with erectile dysfunction who previously did not respond to PDE5 inhibitors were treated with testosterone enanthate injections and daily tadalafil. Patients were stratified into two groups depending on the level of testosterone deficiency, with 250 ng dl(-1) as a reference point. Following testosterone supplementation (12 weeks) and combination therapy (12 weeks), patients with severe testosterone deficiency showed higher IIEF (International Index of Erectile Function) erectile function (EF) domain score (16.47±4.019 vs 12.36±4.051, P=0.001) and more patients responding satisfactorily to treatment by general assessment (57.9 vs 16.0%, P=0.009), despite reaching similar levels of serum total testosterone (602±169 ng dl(-1) vs 698±165 ng dl(-1), P=0.057). Testosterone supplementation was then discontinued and patients were maintained only on daily tadalafil (12 weeks). The severe depletion group maintained higher EF domain scores than baseline (13.06±3.38 vs 7.20±2.24, P=0.0004), despite testosterone levels returning to baseline. The results suggest that combination therapy was more beneficial to patients with severe testosterone depletion, possibly by improving underlying pathophysiology.

Treatment satisfaction with low-dose tamsulosin for symptomatic benign prostatic hyperplasia: results from a multicentre cross-sectional survey.

AIMS: To evaluate the efficacy and treatment satisfaction with low-dose (0.2 mg) tamsulosin in patients with symptomatic benign prostatic hyperplasia (BPH), and to investigate individual lower urinary tract symptoms according to treatment satisfaction. METHODS: A cross-sectional study was conducted in a total sample of 2574 patients from multiple centres. International Prostate Symptom Score (IPSS), prostate volume, uroflowmetry and combined medications were reviewed. Detailed questionnaires were used to assess treatment satisfaction and IPSS 8 weeks after treatment with low-dose tamsulosin. RESULTS: After 8 weeks of treatment with low-dose tamsulosin, IPSS improved significantly. Among the 2574 patients, 1,630 (63.42%) were satisfied and 940 patients (36.50%) were dissatisfied with low-dose tamsulosin. The reasons for dissatisfaction included efficacy problems (84.66%) and side effects (3.72%). Treatment satisfaction was affected by symptom duration, baseline IPSS, and prostate size (p = 0.0441, < 0.001, < 0.009, respectively). IPSS voiding (IPSS-V) and IPSS storage (IPSS-S) after treatment differed significantly depending on the degree of satisfaction (p < 0.001). IPSS-V after treatment did not improve in patients who were 'not satisfied' or 'totally not satisfied' (p = 0.170, 0.240, respectively). All the individual IPSS items except urgency (p = 0.1436) varied significantly with the degree of satisfaction (p < 0.001). CONCLUSIONS: Treating symptomatic BPH with low-dose tamsulosin improved IPSS, but more than one-third of patients were dissatisfied with the treatment. The main reason for dissatisfaction was efficacy problems, and the degree of satisfaction was related to symptom duration, baseline IPSS, and prostate size, and also to IPSS-V. In patients with severe LUTS, the tamsulosin dose should be increased earlier.

Positive emotional learning is regulated in the medial prefrontal cortex by GluN2B-containing NMDA receptors.

In rats, hedonic ultrasonic vocalizations (USVs) is a validated model of positive affect and is best elicited by rough-and-tumble play. Here we report that modulation of GluN2B-containing NMDA receptors (NMDAR) in the medial prefrontal cortex (MPFC) is involved in positive emotional learning. Rough and tumble play increased both GluN1 and GluN2B NMDAR subunit mRNA and protein levels in the frontal cortex. GLYX-13, a GluN2B-preferring, NMDAR glycine-site partial agonist (1 mg/kg, i.v.) significantly increased positive emotional learning whereas the GluN2B receptor-specific antagonist, ifenprodil (10 mg/kg, i.p.), inhibited positive emotional learning. Animals selectively bred for low rates of hedonic USVs were returned to wild-type levels of positive emotional learning following GLYX-13 treatment. MPFC microinjections of GLYX-13 (0.1-10 µg/side) significantly increased rates of positive emotional learning. Thus GluN2B-containing NMDARs may be involved in positive emotional learning in the MPFC by similar mechanisms as spatial/temporal learning in the hippocampus.

The effects of long-term administration of oral desmopressin on the baseline secretion of antidiuretic hormone and serum sodium concentration for the treatment of nocturia: a circadian study.

PURPOSE: We assessed the effects of long-term oral desmopressin on serum sodium and baseline antidiuretic hormone secretion in elderly patients with nocturia. MATERIALS AND METHODS: A total of 15 elderly male patients with severe nocturia (greater than 3 voids nightly) who did not show hyponatremia within 7 days of administration of 0.2 mg desmopressin were enrolled in this study. Desmopressin (0.2 mg) was administered orally nightly for 1 year. Before and 1 month after the 1-year medication 24-hour circadian studies were performed to monitor changes in antidiuretic hormone. Every 3 months during the 1-year medication serum changes and timed urine chemistry were monitored. RESULTS: Desmopressin significantly decreased nocturnal urine output and the number of nocturia episodes (p<0.01). Compared to before treatment desmopressin gradually decreased serum sodium and induced statistically but not clinically significant hyponatremia after 6 months of treatment. After discontinuing desmopressin serum sodium returned to the normal range in all patients. There were no significant differences when baseline and posttreatment endogenous antidiuretic hormone were compared. No serious systemic complications were found during medication. CONCLUSIONS: Long-term desmopressin administration gradually decreased the serum concentration and induced significant hyponatremia from 6 months in patients who did not show initial hyponatremia. Long-term administration of desmopressin for 1 year in elderly patients did not affect baseline antidiuretic hormone secretion. For long-term desmopressin administration serum sodium should be assessed regularly, at least every 6 months.

Galantamine increases excitability of CA1 hippocampal pyramidal neurons.

Galantamine is a third generation cholinesterase inhibitor and an allosteric potentiating ligand of nicotinic acetylcholine receptors. It enhances learning in aging rabbits and alleviates cognitive deficits observed in patients with Alzheimer's disease. We examined galantamine's effect on CA1 neurons from hippocampal slices of young and aging rabbits using current-clamp, intracellular recording techniques. Galantamine (10-200 microM) dose-dependently reduced the postburst afterhyperpolarization and the spike-frequency accommodation of CA1 neurons from both young and aging animals. These reductions were partially, but significantly, reversed by the addition of the muscarinic receptor antagonist, atropine (1 microM), to the perfusate. In contrast, the nicotinic acetylcholine receptor antagonist, alpha-bungarotoxin (10 nM), had no effect; i.e. alpha-bungarotoxin did not reverse the afterhyperpolarization and accommodation reductions. The allosteric potentiating ligand effect was examined by stimulating the Schaffer collateral and measuring the excitatory postsynaptic potentials for 30 min during bath application of galantamine. Galantamine (200 microM) significantly enhanced the excitatory postsynaptic potential amplitude and area over time. These effects were blocked by 10 nM alpha-bungarotoxin, supporting a role for galantamine as an allosteric potentiating ligand. We did not observe a facilitation of the excitatory postsynaptic potentials with 1 microM galantamine. However, when the excitatory postsynaptic potential was pharmacologically isolated by adding 10 microM gabazine (GABA(A) receptor antagonist) to the perfusate, 1 microM galantamine potentiated the subthreshold excitatory postsynaptic potentials into action potentials. We propose that the learning enhancement observed in aging animals and the alleviation of cognitive deficits associated with Alzheimer's disease after galantamine treatment may in part be due to the enhanced function of both nicotinic and muscarinic excitatory transmission on hippocampal pyramidal neurons.

Synergistic effects of sildenafil on relaxation of rabbit and rat cavernosal smooth muscles when combined with various vasoactive agents.

OBJECTIVE: To evaluate which vasoactive agents have synergistic effects on the cavernosal smooth muscles of rabbits and rats when the agents are combined with sildenafil. MATERIALS AND METHODS: Relaxation responses of cavernosal smooth muscle to single agents (phentolamine, moxisylyte, sodium nitroprusside, forskolin, vasoactive intestinal peptide, VIP, papaverine and sildenafil) in the rabbit, and prostaglandin-E1 and sildenafil in the rat, and to combinations of each agent plus sildenafil, were assessed in vitro. The response to sildenafil of the rabbit strips with and without incubation with l-arginine (1 mmol/L) for 20 min was also evaluated. The effective concentrations for a half-maximal response of single agents and combination solutions were compared. RESULTS: All single agents induced concentration-dependent relaxation of the rabbit and rat cavernosal smooth muscles. There was significant synergism on rabbit cavernosal smooth muscle when the sildenafil was combined with forskolin, sodium nitroprusside, VIP or phentolamine. There was also significant synergism with sildenafil plus prostaglandin-E1 in rat cavernosal muscles. There were no synergistic effects of combinations of sildenafil plus moxisylyte, papaverine or l-arginine. CONCLUSIONS: These results suggest potentially effective combined therapies of sildenafil and intraurethral or intracavernosal prostaglandin-E1, intracavernosal forskolin or VIP, or oral phentolamine for patients with erectile dysfunction who have no success after monotherapy with these agents.

Metrifonate decreases sI(AHP) in CA1 pyramidal neurons in vitro.

Metrifonate, a cholinesterase inhibitor, has been shown to enhance learning in aging rabbits and rats, and to alleviate the cognitive deficits observed in Alzheimer's disease patients. We have previously determined that bath application of metrifonate reduces the spike frequency adaptation and postburst afterhyperpolarization (AHP) in rabbit CA1 pyramidal neurons in vitro using sharp electrode current-clamp recording. The postburst AHP and accommodation observed in current clamp are the result of four slow outward potassium currents (sI(AHP), I(AHP), I(M), and I(C)) and the hyperpolarization activated mixed cation current, I(h). We recorded from visually identified CA1 hippocampal pyramidal neurons in vitro using whole cell voltage-clamp technique to better isolate and characterize which component currents of the AHP are affected by metrifonate. We observed an age-related enhancement of the slow component of the AHP tail current (sI(AHP)), but not of the fast decaying component of the AHP tail current (I(AHP), I(M), and I(C)). Bath perfusion of metrifonate reduced sI(AHP) at concentrations that cause a reduction of the AHP and accommodation in current-clamp recordings, with no apparent reduction of I(AHP), I(M), and I(C). The functional consequences of metrifonate administration are apparently mediated solely through modulation of the sI(AHP).

The M1 muscarinic agonist CI-1017 facilitates trace eyeblink conditioning in aging rabbits and increases the excitability of CA1 pyramidal neurons.

The M1 muscarinic agonist CI-1017 was administered intravenously to aging rabbits on a daily basis before and during hippocampally dependent trace eyeblink conditioning sessions. Circulating levels of CI-1017 were significantly related to the drug dose. The drug was found to significantly increase the rate and amount of learning in a dose-dependent manner with no significant effects on the amplitude, area, or latency of conditioned responses. There was no evidence of pseudoconditioning at the highest drug concentration, and the minimally effective dose produced only mild and temporary hypersalivation as a side effect. CI-1017 (10 microM) was also found to increase the excitability of CA1 pyramidal neurons recorded from hippocampal slices from young and aging naive rabbits as measured by changes in spike-frequency adaptation and the postburst afterhyperpolarization. These biophysical changes were reversed with either atropine (1 microM) or pirenzepine (1 microM). These results suggest that M1 agonists ameliorate age-related learning and memory impairments at least in part by reducing the afterhyperpolarization and spike-frequency adaptation of hippocampal pyramidal neurons and that M1 agonists may be an effective therapy for reducing the cognitive deficits that accompany normal aging and/or Alzheimer's disease.

Cholinergic facilitation of trace eyeblink conditioning in aging rabbits.

The hippocampus is importantly involved in learning and memory, and is severely impacted by aging. In in vitro hippocampal slices, both the post-burst afterhyperpolarization (AHP) and spike-frequency accommodation are reduced in hippocampal pyramidal neurons after hippocampally-dependent trace eyeblink conditioning, indications of increased cellular excitability. The AHP results from the activation of outward potassium currents, including sI(AHP) and muscarine-sensitive I(M). The AHP is significantly increased in aging hippocampal neurons, potentially contributing to age-associated learning deficits. Compounds which reduce the AHP and spike-frequency accommodation could facilitate learning in normal aging or in age-associated dementias such as Alzheimer's disease. The cholinesterase inhibitor metrifonate enhances trace eyeblink conditioning by aging rabbits and reduces the AHP and accommodation in hippocampal CA1 neurons in a dose-dependent manner. These reductions are mediated by muscarinic cholinergic transmission as they are blocked by atropine. Hippocampal neurons from metrifonate treated but behaviorally naive rabbits were more excitable and not desensitized to the effects of metrifonate since the AHP and accommodation were further reduced when metrifonate was bath applied to the neurons. These observations suggest that the facilitating effect of chronic metrifonate on acquisition of hippocampally dependent tasks is mediated at least partially by increasing the baseline excitability of CA1 pyramidal neurons. The issue of whether learning can be facilitated with muscarinic cholinergic agonists, in addition to cholinesterase inhibitors, was addressed by training aging rabbits during intravenous treatment with the M1 agonist CI1017. A dose-dependent enhancement of acquisition was observed, with rabbits receiving 1.0 or 5.0 mg/ml CI1017 showing comparably improved learning rates as those receiving 0.5 mg/ml or vehicle. Sympathetic side effects, mainly excess salivation, were seen with the 5.0 mg/ml dose. Post-training evaluations suggested that the effective doses of CI1017 were enhancing responsivity to the tone conditioned stimulus. These studies suggest that muscarinic cholinergic neurotransmission is importantly involved in associative learning; that learning in aging animals may be facilitated by enhancing cholinergic transmission; and that the facilitation may be mediated through actions on hippocampal neurons.

Metrifonate increases neuronal excitability in CA1 pyramidal neurons from both young and aging rabbit hippocampus.

The effects of metrifonate, a second generation cholinesterase inhibitor, were examined on CA1 pyramidal neurons from hippocampal slices of young and aging rabbits using current-clamp, intracellular recording techniques. Bath perfusion of metrifonate (10-200 microM) dose-dependently decreased both postburst afterhyperpolarization (AHP) and spike frequency adaptation (accommodation) in neurons from young and aging rabbits (AHP: p < 0.002, young; p < 0.050, aging; accommodation: p < 0.024, young; p < 0.001, aging). These reductions were mediated by muscarinic cholinergic transmission, because they were blocked by addition of atropine (1 microM) to the perfusate. The effects of chronic metrifonate treatment (12 mg/kg for 3 weeks) on CA1 neurons of aging rabbits were also examined ex vivo. Neurons from aging rabbits chronically treated with metrifonate had significantly reduced spike frequency accommodation, compared with vehicle-treated rabbits. Chronic metrifonate treatment did not result in a desensitization to metrifonate ex vivo, because bath perfusion of metrifonate (50 microM) significantly decreased the AHP and accommodation in neurons from both chronically metrifonate- and vehicle-treated aging rabbits. We propose that the facilitating effect of chronic metrifonate treatment on acquisition of hippocampus-dependent tasks such as trace eyeblink conditioning by aging subjects may be caused by this increased excitability of CA1 pyramidal neurons.

Pairing-specific long-term depression of Purkinje cell excitatory postsynaptic potentials results from a classical conditioning procedure in the rabbit cerebellar slice.

1. Using a rabbit cerebellar slice preparation, we stimulated a classical conditioning procedure by stimulating parallel fiber inputs to Purkinje cells with the use of a brief, high-frequency train of eight constant-current pulses 80 ms before climbing fiber inputs to the same Purkinje cell were stimulated with the use of a brief, lower frequency train of three constant-current pulses. In all experiments, we assessed the effects of stimulation by measuring the peak amplitude of Purkinje cell excitatory postsynaptic potentials (EPSPs) to single parallel fiber test pulses. 2. Intradendritically recorded Purkinje cell EPSPs underwent a long-term (> 20 min) reduction in peak amplitude (30%) after paired stimulation of the parallel and climbing fibers but not after unpaired or parallel fiber alone stimulation. We call this phenomenon pairing-specific long-term depression (PSD). 3. Facilitation of the peak amplitude of a second EPSP elicited by a parallel fiber train occurred both before and after paired stimulation suggesting that the locus of depression was not presynaptic. Depression of the peak amplitude of a depolarizing response to focal application of glutamate following pairings of parallel and climbing fiber stimulation added support to a suggested postsynaptic locus of the PSD effect. 4. The application of aniracetam potentiated EPSP peak amplitude by 40%, but these values returned to baseline as a result of pairings. With the removal of aniracetam from the bath 20 min after pairings, normal levels of pairing-specific EPSP depression were observed, indicating that the effect did not result from direct desensitization of alpha-amino-3-hydroxy-5-methyl-4-isoxazole-proprionic acid (AMPA) receptors. 5. Incubation of slices in the protein kinase inhibitor H-7 potentiated EPSP peak amplitudes slightly (9%), but peak amplitudes returned to baseline levels after pairings. The net reduction in EPSP peak amplitude of < 10% after pairings suggested that H-7 partially blocked PSD and that, in turn, PSD involved protein kinases. 6. The means of induction and the specificity of those means suggest that the phenomenology of PSD is fundamentally different from that of long-term depression. PSD only occurs with pairings of trains of parallel fiber and climbing fiber stimulation; it occurs without the need for bicuculline; and it can overcome the blocking effects of aniracetam. 7. Nevertheless, the involvement of protein kinases and the potential role of calcium suggest that the mechanisms involved in the induction of PSD and long-term depression have a number of features in common. 8. Because of the pairing-specific nature of the long-term synaptic depression observed in these experiments, PSD provides a mechanism that may contribute to the role of the cerebellar cortex in classical conditioning.

Conditioning-specific modification of the rabbit's unconditioned nictitating membrane response.

Robust classical conditioning modifies responding to the unconditioned stimulus (US) in the absence of the conditioned stimulus (CS), a phenomenon the researchers called conditioning-specific reflex modification. Unconditioned responses (URs) to periorbital stimulation varying in intensity and duration were assessed before and after 1, 3, or 6 days of paired, explicitly unpaired, or no presentations of tone and electrical stimulation. After 3 days of pairings, conditioned responding (CRs) reached 94%, and there was an increase in latency to the peak of URs. The peak latency increase was replicated in a second experiment where rabbits reached asymptotic conditioning during 6 days of pairings. There was also a conditioning-specific increase in the amplitude of URs. There were no UR changes as a function of low level of CRs following 1 day of pairings. Data suggest that there are learning-specific changes in pathways mediating the US/UR, as well as in those mediating the CS/CR.

Norepinephrine involvement in response to intracorporeal injection of papaverine in psychogenic impotence.

The levels of catecholamines in penile blood during a papaverine test were measured to investigate whether the secretion of endogenous catecholamines is involved in response to intracorporeal papaverine injection. The level of norepinephrine was higher in patients with psychogenic impotence than in the normal controls and patients with vasculogenic impotence (p less than 0.01), and it was significantly higher in negative responders than in positive responders in the psychogenic impotence group (p less than 0.001). There was no significant difference in the level of epinephrine among the groups. The false negative response to the papaverine test in psychogenically impotent men is believed to be derived from secretion of cavernous norepinephrine, which overwhelms the action of cavernous smooth muscle relaxation by papaverine.