Characterization of the Binding of Omega-Conopeptides to Different Classes of Non-L-Type Neuronal Calcium Channels

doi:10.1006/mcne.1994.1026

Molecular and Cellular Neuroscience

Volume 5, Issue 3, June 1994, Pages 219-228

https://doi.org/10.1006/mcne.1994.1026 Get rights and content

Abstract

The interaction of two synthetic ω-conopeptides SNX111 (MVIIA) and SNX-230 (MVIIC) both derived from the marine snail Conus magus, with non-L-type neuronal voltage-sensitive calcium channels (VSCC) in rat brain synaptosomal preparations has been investigated with the aid of well-characterized ¹²⁵I derivatives of the two peptides. To assess the effects of iodination on the binding characteristics of SNX-111 and SNX-230, the corresponding peptides containing monoiodotyrosine in place of tyrosine, namely, SNX-259 ([¹²⁷I]SNX-111) and SNX260 ([¹²⁷I]SNX-230), respectively, were prepared by solid-phase synthesis. Saturation analysis showed that [¹²⁷I]SNX-111 and [¹²⁷I]SNX-230 bound to two distinct classes of high-affinity sites with apparent K_d's of 9 and 11 pM and B_max's of 0.54 and 2.2 pmol/mg protein, respectively. Kinetic analysis revealed that both peptides exhibited high association rates as well as rapid dissociation rates in contrast to the ¹²⁵I derivative of the synthetic ω-conopeptide from Conus geographus, GVIA (SNX- 124), which binds irreversibly to N-type channels in rat brain synaptosomes. Competition binding experiments with [¹²⁵I]SNX-111 and [¹²⁵I]SNX-124 established that both of them bind to the same site, namely, N-type VSCC. The site detected by the binding of [¹²⁵I]SNX-230 is distinct from N-type VSCC since SNX-111 has very low affinity (K_i = 135 nM) in competition studies. Recent findings that a novel high-voltage-activated calcium channel in rat cerebellar granule neurons is resistant to blockers of L-, N-, and P-type VSCC but is highly sensitive to SNX-230 suggest that the [¹²⁵I]SNX-230 binding site may represent this novel type of calcium channel or another, as yet undescribed, VSCC.

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2014, Pharmacology Biochemistry and Behavior
Citation Excerpt :
Considerable research in the last decade has focused on N-type calcium channel inhibitors for the development of novel analgesic drugs (Altier and Zamponi, 2004). ω-Conotoxin MVIIA is a selective, reversible and potent blocker of N-type HVCCs (Kristipati et al., 1994; Wang et al., 1998), and it inhibits both neuronal excitability and neurotransmission ω-Conotoxin MVIIA was originally isolated from the cone snail Conus magnus and was subsequently chemically synthesized and called ziconotide. Due to its peptide nature, ziconotide is not orally available, and it must be delivered directly into the CNS via intrathecal administration.
The effects of intrathecal administration of the toxins Phα₁β and ω-conotoxin MVIIA were investigated in visceral nociception induced by an intraperitoneal injection of acetic acid and an intracolonic application of capsaicin. The pretreatments for 2 h with the toxins reduced the number of writhes or nociceptive behaviors compared with the control mice. Phα1β administration resulted in an Imax of 84 ± 6 and an ID₅₀ of 12 (5–27), and ω-conotoxin MVIIA resulted in an Imax of 82 ± 9 and an ID₅₀ of 11 (4–35) in the contortions induced by the intraperitoneal injection of acetic acid. The administration of Phα1β resulted in an Imax of 64 ± 4 and an ID₅₀ of 18 (9–38), and ω-conotoxin MVIIA resulted in an Imax of 71 ± 9 and an ID₅₀ of 9 (1–83) in the contortions induced by intracolonic capsaicin administration. Phα1β (100/site) or ω-conotoxin MVIIA (30 pmol/site) pretreatments caused a reduction in CSF glutamate release in mice intraperitoneally injected with acetic acid or treated with intracolonic capsaicin. The toxin pretreatments reduced the ROS levels induced by intraperitoneal acetic acid injection. Phα1β, but not ω-conotoxin MVIIA, reduced significantly the ROS levels induced by intracolonic capsaicin administration.
Perspective: Phα1β is a ω-toxin with high therapeutic index and a broader action on calcium channels. It shows analgesic effect in several rodents' models of pain, including visceral pain, suggesting that this toxin has the potential to be used in clinical setting as a drug in the control of persistent pathological pain.
Effect of ω-conotoxin MVIIA and Phα1β on paclitaxel-induced acute and chronic pain
2013, Pharmacology Biochemistry and Behavior
The treatment with the chemotherapeutic agent paclitaxel produces a painful peripheral neuropathy, and is associated with an acute pain syndrome in a clinically significant number of patients. However, no standard therapy has been established to manage the acute pain or the chronic neuropathic pain related to paclitaxel. In the present study, we evaluated the analgesic potential of two N-type voltage-gated calcium channel (VGCC) blockers, ω-conotoxin MVIIA and Phα1β, on acute and chronic pain induced by paclitaxel. Adult male rats were treated with four intraperitoneal injections of paclitaxel (1 + 1 + 1 + 1 mg/kg, in alternate days) and the development of mechanical hyperalgesia was evaluated 24 h (acute painful stage) or 15 days (chronic painful stage) after the first paclitaxel injection. Not all animals showed mechanical hyperalgesia 24 h after the first paclitaxel injection, but those that showed developed a more intense mechanical hyperalgesia at the chronic painful stage. Intrathecal administration (i.t.) of ω-conotoxin MVIIA (3–300 pmol/site) or Phα1β (10–300 pmol/site) reduced the mechanical hyperalgesia either at the acute or at the chronic painful stage induced by paclitaxel. When administered at the acute painful stage, ω-conotoxin MVIIA (300 pmol/site, i.t.) and Phα1β (300 pmol/site, i.t.) prevented the worsening of chronic mechanical hyperalgesia. Furthermore, Phα1β (30-300 pmol/site, i.t.) elicited less adverse effects than ω-conotoxin MVIIA (10-300 pmol/site, i.t.). Taken together, our data evidence the involvement of N-type VGCC in pain sensitization induced by paclitaxel and point out the potential of Phα1β as a safer alternative than ω-conotoxin MVIIA to treat the pain related to paclitaxel.
Therapeutic applications of conotoxins
2009, Botulinum Toxin: Therapeutic Clinical Practice and Science, Expert Consult - Online and Print
Therapeutic Applications of Conotoxins
2009, Botulinum Toxin: Therapeutic Clinical Practice and Science
Analgesic effect in rodents of native and recombinant Phα1β toxin, a high-voltage-activated calcium channel blocker isolated from armed spider venom
2008, Pain
Calcium influx through neuronal voltage-sensitive calcium channels (VSCC_S) mediates nociceptive information in the spinal dorsal horn. In fact, spinally administered VSCC_S blockers, such as ω-conotoxin MVIIA, have analgesic effect apart of their low therapeutic index and many side effects. Here we study the analgesic potential of Phα1β, a calcium channel blocker, in rodent models of acute and persistent pain. Spinally administered Phα1β showed higher efficacy and long-lasting analgesia in a thermal model of pain, when compared with ω-conotoxin MVIIA. Moreover, Phα1β was more effective and potent than ω-conotoxin MVIIA not only to prevent, but especially to reverse, previously installed persistent chemical and neuropathic pain. Furthermore, the analgesic action of both toxins are related with the inhibition of Ca²⁺-evoked release of pro-nociceptive neurotransmitter, glutamate, from rat spinal cord synaptosomes and decrease of glutamate overflow in cerebrospinal fluid. When side effects were assessed, we found that Phα1β had a therapeutic index wider than ω- conotoxin MVIIA. Finally, recombinant Phα1β expressed in Escherichia coli showed marked analgesic activity similar to the native toxin. Taken together, the present study demonstrates that native and recombinant Phα1β have analgesic effects in rodent models of pain, suggesting that this toxin may have potential to be used as a drug in the control of persistent pathological pain.
Continuous intrathecal infusion of ziconotide for treatment of chronic malignant and nonmalignant pain over 12 months: A prospective, open-label study
2008, Neuromodulation
This study aims to assess the safety and efficacy of long-term intrathecal (IT) ziconotide infusion.
In this prospective study, 155 patients with severe chronic pain (48 with malignant pain, 107 with nonmalignant pain) who had been responsive to short-term IT ziconotide in a double-blind, placebo-controlled study received long-term, open-label IT ziconotide monotherapy. Efficacy assessments included the mean percentage change on the visual analog scale of pain intensity from baseline in the study of origin; safety was monitored by adverse event (AE) reports, periodic laboratory tests, and vital sign measurements.
At the last available observation, the visual analog scale of pain intensity scores had decreased by a mean of 36.9% from baseline in the short-term trial (N = 144; 95% CI: 30.1–43.7%; p < 0.0001). The mean IT ziconotide dose remained stable over 12 months in the 31 patients who participated in the study for ≥ one year. Ziconotide-related AEs were reported in 147 out of 155 patients (94.8%); 39.4% of patients discontinued treatment because of AEs, the majority of which were considered ziconotide related.
Ziconotide IT monotherapy provided patients with analgesia for 12 months in this open-label study, with an acceptable benefit/risk profile and no evidence of tolerance.

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Regular ArticleCharacterization of the Binding of Omega-Conopeptides to Different Classes of Non-L-Type Neuronal Calcium Channels

Abstract

Regular Article
Characterization of the Binding of Omega-Conopeptides to Different Classes of Non-L-Type Neuronal Calcium Channels