Modulation by desmopressin of neuronal activity in brainstem micturition center

Effects of vasopressin receptor agonists on detrusor smooth muscle tone in young and aged bladders: Implications for nocturia treatment

PURPOSE

The main goal of this study was to determine the effects of arginine vasopressin (AVP) and desmopressin on bladder contractility and to examine whether the effects of these vasopressin receptor (VR) agonists differ in young versus aged animals. These aims were addressed using urinary bladders from young (3 months) and aged (24 month) female Fischer 344 rats that were isolated and dissected into strips for isometric tension recordings. Bladder strips were exposed to AVP and desmopressin through the perfusate, and tension changes recorded.

RESULTS

In young rat bladders, AVP, an agonist at both vasopressin-1 receptors (V₁Rs) and vasopressin-2 receptor (V₂Rs), concentration-dependently caused contraction of bladder strips with a sensitivity that was greater in young versus aged bladder strips. Removal of the mucosa did not alter the sensitivity of young bladder strips to AVP yet enhanced the AVP sensitivity of aged bladder strips. The differential sensitivity to AVP between young denuded and aged denuded bladder strips was similar. In contrast to AVP, desmopressin (V₂R selective agonist) relaxed bladder strips. This response was reduced by removal of the mucosa in young, but not aged, bladder strips.

CONCLUSION

These findings support a direct role for VRs in regulating detrusor tone with V₁Rs causing contraction and V₂Rs relaxation. In aged bladders, the contractile response to V₁R activation is attenuated due to release of a mucosal factor that attenuates V₁R-induced contractions. Also in aged bladders, the relaxation response to V₂R activation is attenuated by lack of release of a mucosal factor that contributes to V₂R-induced relaxation. Thus age-associated changes in the bladder mucosa impair the effects of VRs on bladder tone. Because the V₂R signaling system is impaired in the older bladder, administering an exogenous V₂R agonist (e.g., desmopressin) could counteract this defect. Thus, desmopressin could potentially increase nighttime bladder capacity through detrusor relaxation in concert with decreased urine production, reducing nocturnal voiding frequency.

Children with nocturnal enuresis and attention deficit hyperactivity disorder: A separate entity?

INTRODUCTION

There is ongoing debate about whether nocturnal enuresis (NE) is affected by the presence of attention deficit hyperactivity disorder (ADHD) in children. Clarifying this relationship could categorize them as a separate entity, potentially requiring a different management from enuretic children without ADHD.

AIMS

To study whether (1) children with ADHD exhibited greater severity of enuresis and associated voiding symptoms compared with children without ADHD, (2) whether there was a difference in enuretic response to treatment between children with/without ADHD, (3) whether previously prescribed medication for ADHD affected severity of enuresis or voiding symptoms, and response to treatment.

METHODS

Data on all consecutive children seen with primary NE and ADHD and age- and gender-matched children with NE without ADHD over the course of 2 years were extracted from our database. Controls were identified using a random number generator to choose patients within each age/gender group. Changes in Dysfunctional Voiding Scoring System (DVSS) and Bristol scores were assessed before and after treatment for NE using repeated measures ANOVAs. Number of weekly wet nights was compared between the groups before and after the treatment of enuresis. Children with more than a 50% decrease in number of wet nights per week were categorized as responding to treatment.

RESULTS

Compared with controls, ADHD children (N = 95) had significantly more severe voiding symptoms, NE and constipation (Table). No significant differences were found between children on ADHD medication (63.2%) and those who were not on ADHD medication (36.8%) on any of the demographic and pre-treatment clinical parameters. Similar enuretic response rates to behavioral modification alone were seen in both study (13.5%) and control (12.8%) groups (p = 0.73). Response to pharmacological treatment was seen in nine patients with ADHD (42.9%) and in six (20.7%) controls, with pharmacological intervention being significantly more effective than behavioral modification for patients with ADHD (p = 0.012). Additionally, no difference was found between ADHD patients on and off ADHD medication in terms of response to enuresis treatment.

CONCLUSION

In children with primary NE, the presence of ADHD was associated with more severe NE, voiding symptoms and constipation. The severity of voiding symptoms and/or NE was unrelated to the use of stimulant medication. The response to behavioral modification was comparable in both groups. However, patients with ADHD were significantly more responsive to medication for NE compared with behavioral modification, indicating a possible benefit for earlier pharmacological treatment for enuresis in this population subgroup.

Comparison of nocturia response to desmopressin treatment in elderly men with and without nocturnal polyuria in real-life practice

OBJECTIVES

To evaluate the safety and efficacy of low-dose desmopressin in elderly men with and without nocturnal polyuria (NP) in real-life practice.

METHODS

Patients with lower urinary tract symptoms (LUTS)/ benign prostate hyperplasia (BPH) who were≧ 65 years old with refractory nocturia were enrolled in this study. We retrospectively analysed elderly men treated with adding desmopressin to current medications for nocturia according to category of the baseline nocturnal urine volume. The 48-h frequency volume chart (FVC), International Prostate Symptom Score (IPSS) and quality of life (QoL) were initially assessed and re-evaluated 12 weeks later. Serum sodium level was checked 1 week, 4 weeks, and 12 weeks after initiation of desmopressin therapy or suspected hyponatremia event. The mean change in numbers of nocturnal voids was evaluated for efficacy of treatment.

RESULTS

A total of 136 patients were included with 55 in non-NP group and 81 in NP group. Hypertension was more common in NP group in regard of comorbidities. During treatment period, there were significant reductions of nocturnal voids from 4.22 ± 1.38 to 2.31 ± 0.98 (p < 0.001) in non-NP group and from 4.52 ± 1.23 to 2.07 ± 0.89 (p < 0.001) in NP group. The reduction in nocturnal voids was more significant in NP group (2.44 ± 1.15 vs. 1.91 ± 1.48, p = 0.003). The mean decrease in serum sodium levels were 3.89 ± 1.22 mmol/l (p < 0.001) in non-NP group and 4.69 ± 3.5 mmol/l (p < 0.001) in NP group at the extreme value.

CONCLUSIONS

Long-term treatment with low-dose desmopressin is safe and effective for nocturia with or without NP in elderly patients with LUTS/BPH during real-life practice. Patients should be well informed about the disease and are closely followed.

Connection between expression of inducible nitric oxide synthase (iNOS) in skull base chordoma and lower urinary tract symptoms

OBJECTIVE

To provide first insights into the potential role of iNOS expressed by skull base chordoma, which causes brainstem compression in and around Barrington's nucleus, and its effect on the micturition center.

METHODS

Urodynamic testing of 22 symptomatic patients was performed. All women and men with skull base chordoma treated in two hospitals in Germany between 1986 and 2007 were studied. Lower urinary tract symptoms (LUTS) were documented in patients with acute brainstem compression due to local chordoma growth positive for iNOS expression. Brain magnetic resonance (MRI) images of the lesions of the symptomatic patients were performed.

RESULTS

Of 74 treated patients, 22 (7 women, 15 men) with a median age of 37 years were evaluated with voiding diaries and computer urodynamic investigation. Urodynamic testing of 22 symptomatic patients with positive iNOS expression of skull base chordoma revealed detrusor overactivity in 55 %, low-compliance bladder in 14 %, detrusor sphincter dyssynergia in 45 % and uninhibited sphincter relaxation in 27 %. There was a significant correlation between strong iNOS expression (score 3-6) in skull base chordoma and severe urinary symptoms (p = 0.003, Spearman ρ = 0.526).

CONCLUSIONS

The expression of iNOS in skull base chordoma compressing the dorsolateral pons, in and around Barrington's nucleus, may influence the pontine micturition center (PMC) and be responsible for lower urinary tract symptoms. Nitric oxide may possibly act as a neurotransmitter. We assume that the high infiltration of chordoma with monocyte/macrophages enhances the release of nitric oxide, as monocyte/macrophages are the main source of iNOS.

Comparison of nocturia response to desmopressin treatment between patients with normal and high nocturnal bladder capacity index

OBJECTIVE

To compare efficacy of desmopressin for treatment of nocturia between patients with normal and high nocturnal bladder capacity index (NBCi).

METHODS

Retrospective analysis of adult patients treated with desmopressin for nocturia. Patients were analyzed according to high or normal NBCi value before treatment.

RESULTS

55 patients were identified, aged 49-84, 47 males, 8 females, who started desmopressin 0.2 mg nocte between 2009 and 2011. Two groups (N: normal and H: high NBCi) were similar regarding number, gender, age, 24 h urine volume, and nocturnal urine volume. On treatment, nocturnal volume decreased by mean of 364 mL. Number of nightly voids decreased in N group from 3.11 to 1.50, in H from 3.96 to 1.44. Nocturnal polyuria and nocturia indices also decreased significantly. NBCi remained the same in N group (0.56 on therapy) and in H group decreased to mean 0.63. All on-treatment values were statistically similar in N and H groups. Pretreatment differences were abolished with treatment. NBCi was significantly correlated to nocturia reduction-larger reduction was observed in patients with higher NBCi. In 8/55 patients, hyponatremia was detected, but without clinical consequences.

CONCLUSIONS

The results indicate that the effectiveness of desmopressin on nocturia is not dependent upon the patient's pretreatment NBCi.

Desmopressin is an effective treatment for mixed nocturia with nocturnal polyuria and decreased nocturnal bladder capacity

To investigate the efficacy and safety of desmopressin in patients with mixed nocturia, Patients aged ≥ 18 yr with mixed nocturia (≥ 2 voids/night and a nocturnal polyuria index [NPi] >33% and a nocturnal bladder capacity index [NBCi] >1) were recruited. The optimum dose of oral desmopressin was determined during a 3-week dose-titration period and the determined dose was maintained for 4 weeks. The efficacy was assessed by the frequency-volume charts and the sleep questionnaire. The primary endpoint was the proportion of patients with a 50% or greater reduction in the number of nocturnal voids (NV) compared with baseline. Among 103 patients enrolled, 94 (79 men and 15 women) were included in the analysis. The proportion of patients with a 50% or greater reduction in NV was 68 (72%). The mean number of NV decreased significantly (3.20 to 1.34) and the mean nocturnal urine volume, nocturia index, NPi, and NBCi decreased significantly. The mean duration of sleep until the first NV was prolonged from 118.4 ± 44.1 to 220.3 ± 90.7 min (P<0.001). The overall impression of patients about their quality of sleep improved. Adverse events occurred in 6 patients, including one asymptomatic hyponatremia. Desmopressin is an effective and well-tolerated treatment for mixed nocturia.

Effect of 1-desamino-8-D-arginine vasopressin on prepulse inhibition of startle supports a central etiology of primary monosymptomatic enuresis

OBJECTIVE

To test the hypothesis that 1-desamino-8-D-arginine vasopressin (dDAVP) has an effect on prepulse inhibition (PPI) of startle in patients with primary monosymptomatic enuresis (PME), thus indicating a central effect.

STUDY DESIGN

Patients with PME (n = 21, age 6 to 12 years) were enrolled in a prospective, randomized, double-blinded, cross-over study. Startle reflexes and PPI were measured under dDAVP treatment versus placebo.

RESULTS

The data show that dDAVP has a significant effect on PPI, raising it from 38.88% under placebo to the age-related normal level of 62.6% with dDAVP treatment (P = .0127).

CONCLUSIONS

Our findings revive the concept of a central pathophysiology of PME and offer a different explanation for the effects of dDAVP, which not only acts on the kidney, but also is (as is AVP) a central neurotransmitter with a signal cascade on relevant reflex mechanisms.

Relief of Nocturnal Enuresis by Desmopressin Is Kidney and Vasopressin Type 2 Receptor Independent

Primary nocturnal enuresis (PNE) is a common problem in childhood and adolescence. Although various treatments are highly effective, a common underlying hypothesis on the pathogenesis is lacking. The success of desmopressin, a synthetic analogue of the antidiuretic hormone vasopressin, has been attributed to increased renal water reabsorption that is mediated by activation of the renal vasopressin V2 receptor (V2R). However, this effect does not explain other symptoms of PNE, such as the failure to arouse upon bladder distension. This study identified a family in which one child displayed PNE and coexisting nephrogenic diabetes insipidus, as a result of a novel nonsense mutation in the V2R gene (C358X). Cell-biologic investigations revealed that V2R-C358X is retained in the endoplasmic reticulum and is unstable, which explains his nephrogenic diabetes insipidus. Consistently, extrarenal V2R-mediated responses were absent in the patient who was treated with desmopressin. Administration of desmopressin, however, changed his PNE into nocturia, because he now still voided unchanged high urinary volumes at night but woke up and went to the bathroom. Withdrawal of desmopressin was accompanied by bedwetting, whereas reintroduction again relieved the symptoms. Therefore, these data indicate that neither a functioning renal concentration system nor a functional V2R is needed for the therapeutic benefit of desmopressin in PNE. Rather, it suggests that another vasopressin receptor and other organ(s) is the target for desmopressin to relieve PNE.