Taming the cannabinoids: new potential in the pharmacologic control of lower urinary tract dysfunction

Summary of European Association of Urology (EAU) Guidelines on Neuro-Urology

CONTEXT

Most patients with neuro-urological disorders require life-long medical care. The European Association of Urology (EAU) regularly updates guidelines for the diagnosis and treatment of these patients.

OBJECTIVE

To provide a summary of the 2015 updated EAU Guidelines on Neuro-Urology.

EVIDENCE ACQUISITION

Structured literature searches in several databases were carried out to update the 2014 guidelines. Levels of evidence and grades of recommendation were assigned where possible.

EVIDENCE SYNTHESIS

Neurological disorders often cause urinary tract, sexual, and bowel dysfunction. Most neuro-urological patients need life-long care for optimal life expectancy and quality of life. Timely diagnosis and treatment are essential to prevent upper and lower urinary tract deterioration. Clinical assessment should be comprehensive and usually includes a urodynamic investigation. The neuro-urological management must be tailored to the needs of the individual patient and may require a multidisciplinary approach. Sexuality and fertility issues should not be ignored. Numerous conservative and noninvasive possibilities of management are available and should be considered before a surgical approach is chosen. Neuro-urological patients require life-long follow-up and particular attention has to be paid to this aspect of management.

CONCLUSIONS

The current EAU Guidelines on Neuro-Urology provide an up-to-date overview of the available evidence for adequate diagnosis, treatment, and follow-up of neuro-urological patients.

PATIENT SUMMARY

Patients with a neurological disorder often suffer from urinary tract, sexual, and bowel dysfunction and life-long care is usually necessary. The update of the EAU Guidelines on Neuro-Urology, summarized in this paper, enables caregivers to provide optimal support to neuro-urological patients. Conservative, noninvasive, or minimally invasive approaches are often possible.

Pioneering drugs for overactive bladder and detrusor overactivity: Ongoing research and future directions

The ongoing research on pioneering drug candidates for the overactive bladder (OAB) aimed to overcome the limitations of currently licensed pharmacotherapies, such as antimuscarinics, β3-adrenergic agents, and botulinum neurotoxin, has been reviewed performing a systematic literature review and web search. The review covers the exploratory agents alternative to available medications for OAB and that may ultimately prove to be therapeutically useful in the future management of OAB patients based on preclinical and early clinical data. It emerges that many alternative pharmacological strategies have been discovered or are under investigation in disease-oriented studies. Several potential therapeutics are known for years but still find obstacles to pass the clinical stages of development, while other completely novel compounds, targeting new pharmacological targets, have been recently discovered and show potential to translate into clinical therapeutic agents for idiopathic and neurogenic OAB syndrome. The global scenario of investigational drugs for OAB gives promise for the development of innovative therapeutics that may ultimately prove effective as first, combined or second-line treatments within a realistic timescale of ten years.

Cannabinoids and the endocannabinoid system in lower urinary tract function and dysfunction

AIMS

To review knowledge on cannabinoids and the endocannabinoid system in lower urinary tract function and dysfunction.

METHODS

Review of MEDLINE using defined search terms, and manual analysis. Articles published in English were included.

RESULTS AND DISCUSSION

Components of the endocannabinoid system—cannabinoid (CB)receptor types 1 and 2, anandamide, and fatty acid amide hydrolase (FAAH), which degrades anandamide and related fatty-acid amides—have been located to lower urinary tract tissues of mice, rats, monkeys, and humans. Studies have located CB receptors in urothelium and sensory nerves and FAAH in the urothelium. CB receptor- and FAAH-related activities have also been reported in the lumbosacral spinal cord. Data on supraspinal CB functions in relation to micturition are lacking. Cannabinoids are reported to reduce sensory activity of isolated tissues, cause antihyperalgesia in animal studies of bladder inflammation, affect urodynamics parameters reflecting sensory functions in animals models, and appear to have effects on storage symptoms in humans. FAAH inhibitors have affected sensory bladder functions and reduced bladder overactivity in rat models. Cannabinoids may modify nerve-mediated functions of isolated lower urinary tract tissues.

CONCLUSIONS

Evidence suggests components of the endocannabinoid system are involved in regulation of bladder function, possibly at several levels of the micturition pathway. It is unclear if either CB receptor has a dominant role in modification of sensory signals or if differences exist at peripheral and central nervous sites. Amplification of endocannabinoid activity by FAAH inhibitors may be an attractive drug target in specific pathways involved in LUTS.

Spinal cord FAAH in normal micturition control and bladder overactivity in awake rats

PURPOSE

We assessed whether spinal inhibition of the cannabinoid degrading enzyme FAAH would have urodynamic effects in normal rats and rats with bladder overactivity induced by partial urethral obstruction or prostaglandin E2. We also determined the expression of FAAH, and the cannabinoid receptors CB1 and CB2 in the sacral spinal cord.

MATERIALS AND METHODS

We used 44 rats for functional (cystometry) and Western blot experiments. The FAAH inhibitor oleoyl ethyl amide (3 to 300 nmol) was administered intrathecally (subarachnoidally) or intravenously. The expression of FAAH and CB1/CB2 receptors was determined by Western blot.

RESULTS

Oleoyl ethyl amide given intrathecally affected micturition in normal rats and rats with bladder overactivity but effects were more pronounced in the latter. In normal rats oleoyl ethyl amide only decreased micturition frequency, while it decreased frequency and bladder pressures in rats with bladder overactivity. Intravenous oleoyl ethyl amide (3 to 300 nmol) had no urodynamic effect. FAAH and CB1/CB2 receptors were expressed in the rat sacral spinal cord. The expression of CB1/CB2 receptors but not FAAH was higher in obstructed than in normal rats.

CONCLUSIONS

FAAH inhibition in the sacral spinal cord by oleoyl ethyl amide resulted in urodynamic effects in normal rats and rats with bladder overactivity. The spinal endocannabinoid system may be involved in normal micturition control and it appears altered when there is bladder overactivity.

Diuretic effects of cannabinoids

In vivo effects of cannabinoid (CB) agonists are often assessed using four well-established measures: locomotor activity, hypothermia, cataleptic-like effects, and analgesia. The present studies demonstrate that doses of CB agonists that produce these effects also reliably increase diuresis. Diuretic effects of several CB agonists were measured in female rats over 2 hours immediately after drug injection, and results were compared with hypothermic effects. Direct-acting CB1 agonists, including Δ(9)-tetrahydrocannabinol, WIN 55,212 [R-(1)-[2,3-dihydro-5-methyl-3-[(morpholinyl)methyl]pyrrolo[1,2,3-de]-1,4-benzoxazinyl]-(1-naphthalenyl)methanone mesylate], AM2389 [9β-hydroxy-3-(1-hexyl-cyclobut-1-yl)-hexahydrocannabinol], and AM4054 [9β-(hydroxymethyl)-3-(1-adamantyl)-hexahydrocannabinol], produced dose-dependent increases in diuresis and decreases in colonic temperature, with slightly lower ED(50) values for diuresis than for hypothermia. The highest doses of cannabinoid drugs yielded, on average, 26-32 g/kg urine; comparable effects were obtained with 10 mg/kg furosemide and 3.0 mg/kg trans-(-)-3,4-dichloro-N-methyl-N-[2-(1-pyrrolidinyl)cyclohexyl]benzeneacetamide (U50-488). Methanandamide (10.0 mg/kg) had lesser effect than other CB agonists, and the CB2 agonist AM1241 [1-(methylpiperidin-2-ylmethyl)-3-(2-iodo-5-nitrobenzoyl)indole], the anandamide transport inhibitor AM404, and the CB antagonist rimonabant did not have diuretic effects. In further studies, the diuretic effects of the CB1 agonist AM4054 were similar in male and female rats, displayed a relatively rapid onset to action, and were dose-dependently antagonized by 30 minutes pretreatment with rimonabant, but not by the vanilloid receptor type I antagonist capsazepine, nor were the effects of WIN 55,212 antagonized by the CB2 antagonist AM630 [(6-iodo-2-methyl-1-[2-(4-morpholinyl)ethyl]-1H-indol-3-yl](4-methoxyphenyl) methanone)]. These data indicate that cannabinoids have robust diuretic effects in rats that are mediated via CB1 receptor mechanisms.