Spinal blockage of P/Q‐ or N‐type voltage‐gated calcium channels modulates functional and symptomatic changes related to haemorrhagic cystitis in mice

Abstract

BACKGROUND AND PURPOSESpinal voltage-gated calcium channels (VGCCs) are pivotal regulators of painful and inflammatory alterations, representing attractive therapeutic targets. We examined the effects of epidural administration of the P/Q-and N-type VGCC blockers Tx3-3 and Phα1β, respectively, isolated from the spider Phoneutria nigriventer, on symptomatic, inflammatory and functional changes allied to mouse cyclophosphamide (CPA)-induced haemorrhagic cystitis (HC). The effects of P. nigriventer-derived toxins were compared with those displayed by MVIIC and MVIIA, extracted from the cone snail Conus magus. EXPERIMENTAL APPROACHHC was induced by a single i.p. injection of CPA (300 mg·kg -1 ). Dose-and time-related effects of spinally administered P/Q and N-type VGCC blockers were assessed on nociceptive behaviour and macroscopic inflammation elicited by CPA. The effects of toxins were also evaluated on cell migration, cytokine production, oxidative stress, functional cystometry alterations and TRPV1, TRPA1 and NK1 receptor mRNA expression. KEY RESULTSThe spinal blockage of P/Q-type VGCC by Tx3-3 and MVIIC or N-type VGCC by Phα1β attenuated nociceptive and inflammatory events associated with HC, including bladder oxidative stress and cytokine production. CPA produced a slight increase in bladder TRPV1 and TRPA1 mRNA expression, which was reversed by all the toxins tested. Noteworthy, Phα1β strongly prevented bladder neutrophil migration, besides HC-related functional alterations, and its effects were potentiated by co-injecting the selective NK1 receptor antagonist CP-96345. CONCLUSIONS AND IMPLICATIONSOur results shed new light on the role of spinal P/Q and N-type VGCC in bladder dysfunctions, pointing out Phα1β as a promising alternative for treating complications associated with CPA-induced HC.

Rho Kinase and Protein Kinase C Pathways are Responsible for Enhanced Carbachol Contraction in Permeabilized Detrusor in a Rat Model of Cystitis

“…Furthermore, the activation of voltage‐gated calcium 3.2 T‐type channels is related to bladder pain and referred hyperalgesia in mice with cyclophosphamide‐induced cystitis . P/Q‐type and N‐type voltage‐gated calcium channels are involved in nociceptive and inflammatory events .…”

Intrathecal administration of TRPA1 antagonists attenuate cyclophosphamide-induced cystitis in rats with hyper-reflexia micturition

“…This proposal is further supported by previous findings showing that TRPA1 mediates sustained hyperalgesic responses in different models [ 14 , 27 ]. Indeed, it has been demonstrated that spinal blockage of the N-type and P/Q-type VGCC (voltage-gated calcium channel) could attenuate inflammatory and nociceptive events associated with cystitis [ 10 ]. Consistent to this notion, TRPA1 located on DRG contributes to the transmission of nociceptive information to second-order neurons in the spinal dorsal horn [ 14 , 26 ].…”

“…The main syndrome of acute cystitis is urinary frequency, urgency and dysuria in addition to the impairment of patient quality of life. Chemical cystitis is the key adverse effect observed with cyclophosphamide (CY) chemotherapy, and it results from the formation of acrolein, which is a known agonist of TRPA1 [ 9 , 10 ]. The TRPA1 channel has been suggested to mediate mechanical and nociceptive sensitivity in both physiological and pathological states of the lower urinary tract [ 11 ].…”

Evaluation of DNA damage in spinal cord and mutagenic effect of a Phα1β recombinant toxin with analgesic properties from the Phoneutria nigriventer spider

“…In fact, these toxins have different antinociceptive effects when compared with ω‐CTx‐MVIIA, which have been explained due to diverse actions on N‐type VGCC or due to inhibition on other VGCC such as R‐type, P/Q‐type and L‐type . In addition, Phα1β and CTK 01512‐2 have shown antagonism on TRPA1 channels, besides acting on VGCC, which may increase not only their antinociceptive effects, but also their adverse reaction . Otherwise, ω‐CTx‐MVIIA is a selective and reversible blocker of the N‐type VGCC, preventing calcium influx .…”

“…N‐type VSCC are widely found in spinal cord neurons and control the release of neurotransmitters, playing an important role in the ascending peripheral pain to the brain . Some studies have shown that Phα1β toxin has antinociceptive action in several rodent pain models, showing effects on acute and persistent pain, including visceral, neuropathic, inflammatory, surgical and cancer pains …”