DFL23448, A Novel Transient Receptor Potential Melastin 8-Selective Ion Channel Antagonist, Modifies Bladder Function and Reduces Bladder Overactivity in Awake Rats

Abstract

The transient receptor potential melastin 8 ion channel (TRPM8) is implicated in bladder sensing but limited information on TRPM8 antagonists in bladder overactivity is available. This study characterizes a new TRPM8-selective antagonist (DFL23448 [5-(2-ethyl-2H-tetrazol-5-yl)-2-(3-fluorophenyl)-1,3-thiazol-4-ol]) and evaluates it in cold-induced behavioral tests and tests on bladder function and experimental bladder overactivity in vivo in rats. DFL23448 displayed IC 50 values of 10 and 21 nM in hTRPM8 human embryonic kidney 293 cells activated by Cooling Agent 10 or cold, but it had limited activity (IC 50 . 10 mM) at transient receptor potential vanilloids TRPV1, TRPA1, or TRPV4 or at various G protein-coupled receptors. In rats, DFL23448 administered intravenously or orally had a half-life of 37 minutes or 4.9 hours, respectively. DLF23448 (10 mg/kg i.v.) reduced icilininduced "wet dog-like" shakes in rats. Intravesical DFL23448 (10 mg/l), but not vehicle, increased micturition intervals, micturition volume, and bladder capacity. During bladder overactivity by intravesical prostaglandin E 2 (PGE 2 ), vehicle controls exhibited reductions in micturition intervals, micturition volumes, and bladder capacity by 37%-39%, whereas the same parameters only decreased by 12%-15% (P , 0.05-0.01 versus vehicle) in DFL23448-treated rats. In vehicle-treated rats, but not in DFL23448-treated rats, intravesical PGE 2 increased bladder pressures. Intravenous DFL23448 at 10 mg/kg, but not 1 mg/kg DFL23448 or vehicle, increased micturition intervals, micturition volumes, and bladder capacity. During bladder overactivity by intravesical PGE 2 , micturition intervals, micturition volumes, and bladder capacity decreased in vehicle-and 1 mg/kg DFL23448-treated rats, but not in 10 mg/kg DFL23448-treated rats. Bladder pressures increased less in rats treated with DFL23448 10 mg/kg than in vehicle-or 1 mg/kg DFL23448-treated rats. DFL23448 (10 mg/kg i.v.), but not vehicle, prevented cold stress-induced bladder overactivity. Our results support a role for bladder TRPM8-mediated signals in experimental bladder overactivity.

Antinociceptive effect of two novel transient receptor potential melastatin 8 antagonists in acute and chronic pain models in rat

“…In contrast with the above preclinical results, in the first clinical trial conducted in healthy volunteers using a TRPM8 antagonist, PF‐05105679, the compound showed a clear pharmacological activity on cold pain in the absence of hypothermia at any dose tested (Winchester et al, ), paving the way to further clinical investigation on this class of molecules. Several new TRPM8 antagonists have been reported to be effective in vitro in the nanomolar range and investigated for their therapeutic potential in the treatment of cold hypersensitivity in different neuropathic pain models and in the management of urological disorders (Patel et al, ; Lehto et al, ; Mistretta et al, ). To confirm the involvement of this channel in pain, it has been demonstrated that TRPM8 is necessary for the detection of chemical and thermal cooling stimuli in some sensory neurons and that TRPM8 knockout CCI‐mice did not exhibit significant increase in acetone‐induced cold allodynia (Colburn et al, ).…”

TRP Channels as Lower Urinary Tract Sensory Targets

“…Several new antagonists have been described [124,125], and some of them have been tested in animals for their effects on normal LUT and in models of LUT disorders [80,82,126,127,128,129,130].…”

TRPM8 and Migraine

“…Several studies have shown activation of bladder TRPM8 decreases volume of bladder filling and decreases voiding intervals while antagonists cause the opposite effects, leading to the possibility of TRPM8 antagonists as therapeutics for conditions such as overactive bladder. Two recent preclinical studies further support this concept, one using menthol as a TRPM8 activator to increase activity of mechanically sensitive bladder afferents while the other used a newly characterized TRPM8 antagonist, DFL23448, to attenuate overactive bladder symptoms . There is also interest in TRPM8 as a therapeutic target for cancer as channel expression has been demonstrated in numerous tumor types .…”

“…Two recent preclinical studies further support this concept, one using menthol as a TRPM8 activator to increase activity of mechanically sensitive bladder afferents while the other used a newly characterized TRPM8 antagonist, DFL23448, to attenuate overactive bladder symptoms. 73,74 There is also interest in TRPM8 as a therapeutic target for cancer 75 as channel expression has been demonstrated in numerous tumor types. 76 However, it remains unclear at this point how to target the channel as activation of TRPM8 can either promote tumor survival or decrease tumor viability, depending on the tumor.…”

“…Recent examples of novel TRPM8 modulators include compounds 12 (inhibitor) and 21 (activator), 78 and the blockers PF-05105679, 79 AMG2850, 70 compound 45 80 (this compound is the same as AMG1161 in 67 ), RQ-00203078, 81 another compound 12, 82 and DFL23448. 73 Interestingly, a recent report from a team at Amgen used commercially available TRPM8 antibodies that recognize epitopes on the extracellular surface as antagonists to block channel function. 83 Use of one of these antibodies as an antagonist (ACC-049) was able to block multiple modes of channel activation (eg, cold, menthol, and icilin) in both cell lines and DRG neurons providing proof of concept that antagonist antibodies for TRPM8 can potentially be developed.…”