Increased plasma norepinephrine concentration in cats with interstitial cystitis

Small Fiber Polyneuropathy May Be a Nexus Between Autonomic Nervous System Dysregulation and Pain in Interstitial Cystitis/Bladder Pain Syndrome

Interstitial cystitis/bladder pain syndrome (IC/BPS) is a highly heterogeneous chronic and debilitating condition which effects millions of women and men in the United States. While primarily defined by urinary symptoms and pain perceived to be emanating from the bladder, IC/BPS patients frequently have co-occurring conditions and symptoms, many of which affect diverse body systems related to autonomic nervous system function. The impact on the autonomic system appears to stem from increased sympathetic innervation of the urinary tract, along with increased systemic sympathetic tone and decreased parasympathetic tone. Concurrent with these findings is evidence for destruction of peripheral sympathetic innervation to the sweat glands which may relate to small fiber polyneuropathy. It is unknown to what degree the wider alterations in autonomic function are also related to destruction/alterations in the small fibers carrying autonomic innervation. This potential nexus is an important point of investigation to better understand the unclarified pathophysiology of interstitial cystitis/bladder pain syndrome, the numerous co-occurring symptoms and syndromes, and for the identification of novel targeted therapeutic strategies.

Stress-induced autonomic dysregulation of mitochondrial function in the rat urothelium

AIM

Chronic stress exacerbates the symptoms of most pain disorders including interstitial cystitis/bladder pain syndrome (IC/BPS). Abnormalities in urothelial cells (UTC) occur in this debilitating bladder condition. The sequence of events that might link stress (presumably through increased sympathetic nervous system-SNS activity) to urothelial dysfunction are unknown. Since autonomic dysregulation, mitochondrial dysfunction, and oxidative stress all occur in chronic pain, we investigated whether chronic psychological stress initiated a cascade linking these three dysfunctions.

METHODS

Adult female Wistar Kyoto rats were exposed to 10 days of water avoidance stress (WAS). Bladders were then harvested for Western blot and single cell imaging in UTC cultures.

RESULTS

UTC from WAS rats exhibited depolarized mitochondria membrane potential (Ψm ∼30% more depolarized compared to control), activated AMPK and altered UT mitochondria bioenergetics. Expression of the fusion protein mitofusion-2 (MFN-2) was upregulated in the mucosa, suggesting mitochondrial structural changes consistent with altered cellular metabolism. Intracellular calcium levels were elevated in cultured WAS UTC, consistent with impaired cellular function. Stimulation of cultured UTC with alpha-adrenergic (α-AR) receptor agonists increased reactive oxidative species (ROS) production, suggesting a direct action of SNS activity on UTC. Treatment of rats with guanethidine to block SNS activity prevented most of WAS-induced changes.

CONCLUSIONS

Chronic stress results in persistent sympathetically mediated effects that alter UTC mitochondrial function. This may impact the urothelial barrier and signaling, which contributes to bladder dysfunction and pain. This is the first demonstration, to our knowledge, of a potential autonomic mechanism directly linking stress to mitochondrial dysfunction.

A new perspective on the pathogenesis of chronic renal disease in captive cheetahs (Acinonyx jubatus)

The sustainability of captive cheetah populations is limited by high mortality due to chronic renal disease. This necropsy study, conducted on 243 captive cheetahs from one institution, investigated the relationships between focal palatine erosions, gastritis, enterocolitis, glomerulosclerosis, chronic renal infarcts, renal cortical and medullary fibrosis, and renal medullary amyloidosis at death. Associations between the individual renal lesions and death due to chronic renal disease and comparisons of lesion prevalence between captive bred and wild born and between normal and king coated cheetahs were also assessed. All lesions were significantly positively correlated with age at death. Renal medullary fibrosis was the only lesion associated with the likelihood of death being due to chronic renal disease, and cheetahs with this lesion were younger, on average, than cheetahs with other renal lesions. Alimentary tract lesions were not associated with amyloidosis. All lesions, except for palatine erosions, were more common in wild born than in captive bred cheetahs; the former were older at death than the latter. Having a king coat had no clear effect on disease prevalence. These results suggest that age and renal medullary fibrosis are the primary factors influencing the pathogenesis of chronic renal disease in captive cheetahs. Apart from amyloidosis, these findings are analogous to those described in chronic renal disease in domestic cats, which is postulated to result primarily from repetitive hypoxic injury of renal tubules, mediated by age and stress. Cheetahs may be particularly susceptible to acute renal tubular injury due to their propensity for stress and their extended life span in captivity, as well as their adaptation for fecundity (rather than longevity) and adrenaline-mediated high speed prey chases. The presence of chronic renal disease in subadult cheetahs suggests that prevention, identification and mitigation of stress are critical to the successful prevention of chronic renal disease in captive cheetahs.

Animal Modelling of Interstitial Cystitis/Bladder Pain Syndrome

The etiology of interstitial cystitis/bladder pain syndrome (IC/BPS) remains elusive and may involve multiple causes. To better understand its pathophysiology, many efforts have been made to create IC/BPS models. Most existing models of IC/BPS strive to recreate bladder-related features by applying noxious intravesical or systemic stimuli to healthy animals. These models are useful to help understand various mechanisms; however, they are limited to demonstrating how the bladder and nervous system respond to noxious stimuli, and are not representative of the complex interactions and pathophysiology of IC/BPS. To study the various factors that may be relevant for IC/BPS, at least 3 different types of animal models are commonly used: (1) bladder-centric models, (2) models with complex mechanisms, and (3) psychological and physical stressors/natural disease models. It is obvious that all aspects of the human disease cannot be mimicked by a single model. It may be the case that several models, each contributing to a piece of the puzzle, are required to recreate a reasonable picture of the pathophysiology and time course of the disease(s) diagnosed as IC/BPS, and thus to identify reasonable targets for treatment.

Sympathetic nervous system and chronic bladder pain: a new tune for an old song

Chronic bladder pain (CBP) patients present with pelvic pain or discomfort during bladder filling, for at least a period of 6 months, which may be accompanied by lower urinary tract symptoms such as frequency, nocturia, and urgency. However, both the etiology of CBP and pathophysiological mechanisms are not well described. A number of clinical and basic animal model findings support involvement of sympathetic nervous system in chronic pain syndromes such as CBP. Examples include sympathetic overactivity and high plasma or urinary catecholamine levels that have a high correlation with nociceptive symptoms. In this review, we explored the current evidence in support of the involvement of sympathetic overactivity in CBP. As bladder inflammation often occurs among subgroups of CBP patients, we discuss the possible role of sympathetic nervous system in mastocytosis as well examples examples of animal models that further support the involvement of sympathetic dysfunction in CBP. As there is substantive evidence for cross-organ sensitization in the pelvis can lead to co-morbidity of genitourinary and gastrointestinal dysfunctions, we also include how sympathetic dysfunction may play a role in a number of co-morbid chronic pain syndromes.

Interstitial Cystitis - Elucidation of Psychophysiologic and Autonomic Characteristics (the ICEPAC Study): design and methods

BACKGROUND AND PURPOSE

Interstitial cystitis/bladder pain syndrome (IC/BPS) is relatively common and associated with severe pain, yet effective treatment remains elusive. Research typically emphasized the bladder's role, but given the high presence of systemic comorbidities, the authors hypothesized a pathophysiologic nervous system role. This paper reports the methodology and approach to study the nervous system in women with IC/BPS. The study compares neurologic, urologic, gynecologic, autonomic, gastrointestinal, and psychological features of women with IC/BPS, their female relatives, women with myofascial pelvic pain (MPP), and healthy controls to elucidate the role of central and peripheral processing.

METHODS AND RESULTS

In total, 228 women (76 IC/BPS, 76 MPP, 38 family members, and 38 healthy controls) will be recruited. Subjects undergo detailed screening, structured neurologic examination of limbs and pelvis, tender point examination, autonomic testing, electrogastrography, and assessment of comorbid functional dysautonomias. Interpreters are blinded to subject classification. Psychological and stress response characteristics are examined with assessments of stress, trauma history, general psychological function, and stress response quantification. As of December 2012, data collection is completed for 25 healthy controls, 33 IC/BPS ± MPP, eight MPP, and three family members. Recruitment rate is accelerating and strategies emphasize maintaining and encouraging investigator participation in study science, internet advertising, and presentations to pelvic pain support groups.

CONCLUSION

The study represents a comprehensive, interdisciplinary approach to sampling autonomic and psychophysiologic characteristics of women with IC/BPS. Despite divergent opinions on study methodologies based on specialty experiences, the study has proven feasible to date and different perspectives have proved to be one of the greatest study strengths.

Pharmacodynamic effects of ivabradine, a negative chronotropic agent, in healthy cats

OBJECTIVE

To determine the pharmacodynamic effects of oral ivabradine in cats.

ANIMALS

Eight healthy, adult domestic short hair cats.

METHODS

Each cat underwent four study periods of 24 h, receiving either one dose of placebo or ivabradine (0.1 mg/kg, 0.3 mg/kg, and 0.5 mg/kg) in a single-blind randomized crossover study. Clinical tolerance was assessed hourly for the first 8 h, at 12 h, and at the end of the 24-h study period. Heart rate and blood pressure were monitored continuously for 18-24 h via radiotelemetry after each treatment. Response to stress (acoustic startle) was studied before (t = 0) and after treatment (t = 4 h). Statistical comparisons were made using a linear mixed models and 1-way and 2-way repeated measures ANOVA.

RESULTS

Heart rate (min(-1)) decreased significantly (P < 0.05) in a dose-dependent manner with peak negative chronotropic effects observed 3 h after ivabradine (mean ± SD; placebo, 144 ± 20; ivabradine 0.1 mg/kg, 133 ± 22; ivabradine 0.3 mg/kg, 112 ± 20; and ivabradine 0.5 mg/kg, 104 ± 11). Heart rate (min(-1)) was still reduced (P < 0.05) 12 h after ivabradine (0.3 mg/kg; 128 ± 18 and 0.5 mg/kg; 124 ± 16) compared to placebo (141 ± 21). The tachycardic response to acoustic startle was significantly (P < 0.01) blunted at all 3 doses of ivabradine. Myocardial oxygen consumption estimated by the rate-pressure product was significantly reduced (P < 0.05) for all doses of ivabradine. No effect of ivabradine on systolic, diastolic, and mean blood pressure was identified and no clinically discernable side effects were observed.

CONCLUSION

These findings indicate that a single oral dose of ivabradine predictably lowers heart rate, blunts the chronotropic response to stress, and is clinically well tolerated in healthy cats. This makes ivabradine potentially interesting in the treatment of feline heart disease where ischemia is of pathophysiologic importance.

Idiopathic cystitis in domestic cats--beyond the lower urinary tract

Signs of lower urinary tract (LUT) disease in domestic cats can be acute or chronic, and can result from variable combinations of abnormalities within the lumen of the LUT, the parenchyma of the LUT itself, or other organ system(s) that then lead to LUT dysfunction. In the majority of cats with chronic signs of LUT dysfunction, no specific underlying cause can be confirmed after standard clinical evaluation of the LUT, so these cats typically are classified as having idiopathic cystitis. A syndrome in human beings commonly known as interstitial cystitis (IC) shares many features in common with these cats, permitting comparisons between the two species. A wide range of similarities in abnormalities has been identified between these syndromes outside as well as inside the LUT. A variety of potential familial and developmental risk factors also have been identified. These results have permitted generation of the hypothesis that some of these people have a disorder affecting the LUT rather than a disorder of the LUT. This perspective has suggested alternative diagnostic strategies and novel approaches to treatment, at least in cats. The purpose of this review is to summarize research investigations into the various abnormalities present in cats, to compare some of these findings with those identified in human beings, and to discuss how they might modify perceptions about the etiopathogenesis, diagnosis, and treatment of cats with this disease. Dedication: I dedicate this contribution to Professor Dennis J. Chew, whose collaboration, patience, and support made it all possible.

A protocol for managing urethral obstruction in male cats without urethral catheterization

OBJECTIVE

To determine efficacy of a protocol for managing urethral obstruction (UO) in male cats without urethral catheterization.

DESIGN

Clinical trial.

ANIMALS

15 male cats with UO in which conventional treatment had been declined.

PROCEDURES

Laboratory testing and abdominal radiography were performed, and cats with severe metabolic derangements or urinary calculi were excluded. Treatment included administration of acepromazine (0.25 mg, IM, or 2.5 mg, PO, q 8 h), buprenorphine (0.075 mg, PO, q 8 h), and medetomidine (0.1 mg, IM, q 24 h) and decompressive cystocentesis and SC administration of fluids as needed. Cats were placed in a quiet, dark environment to minimize stress. Treatment success was defined as spontaneous urination within 72 hours and subsequent discharge from the hospital.

RESULTS

Treatment was successful in 11 of the 15 cats. In the remaining 4 cats, treatment was considered to have failed because of development of uroabdomen (n=3) or hemoabdomen (1). Cats in which treatment failed had significantly higher serum creatinine concentrations than did cats in which treatment was successful. Necropsy was performed on 3 cats in which treatment had failed. All 3 had severe inflammatory disease of the urinary bladder, but none had evidence of bladder rupture.

CONCLUSIONS AND CLINICAL RELEVANCE

Results suggested that in male cats, a combination of pharmacological treatment, decompressive cystocentesis, and a low-stress environment may allow for resolution of UO without the need for urethral catheterization. This low-cost protocol could serve as an alternative to euthanasia when financial constraints prevent more extensive treatment.

Randomized controlled trial of the efficacy of short-term amitriptyline administration for treatment of acute, nonobstructive, idiopathic lower urinary tract disease in cats

OBJECTIVE

To determine whether short-term amitriptyline administration would be efficacious in the treatment of acute, nonobstructive, idiopathic lower urinary tract disease in cats.

DESIGN

Randomized controlled trial.

ANIMALS

31 untreated male and female cats with acute, nonobstructive, idiopathic lower urinary tract disease.

PROCEDURES

Cats were treated with amitriptyline (5 mg/d; n = 16) or a placebo (15) for 7 days and monitored for pollakiuria, hematuria, and adverse events. Cats were reexamined 1 month after treatment, and owners were interviewed by telephone 6, 12, and 24 months after treatment.

RESULTS

2 amitriptyline-treated cats were excluded from analyses because of acquired urinary tract infection. Clinical signs resolved by day 8 in 8 amitriptyline-treated and 10 control cats. There were no apparent differences in likelihood or rate of recovery from pollakiuria or hematuria between groups. Overall, clinical signs recurred significantly faster and more frequently in amitriptyline-treated than control cats. However, after excluding recurrences within 21 days of treatment, risk of recurrence was similar in both groups. Increasing age was significantly associated with increased likelihood and rate of recovery from hematuria and with decreased risk of recurrence of signs.

CONCLUSIONS AND CLINICAL RELEVANCE

Results suggest that short-term amitriptyline treatment has no benefit in terms of resolution of pollakiuria and hematuria in cats with idiopathic lower urinary tract disease and may be associated with an increased risk of recurrence.