scholarly journals Dehydrocrenatidine Inhibits Voltage-Gated Sodium Channels and Ameliorates Mechanic Allodia in a Rat Model of Neuropathic Pain

Toxins ◽  
2019 ◽  
Vol 11 (4) ◽  
pp. 229 ◽  
Author(s):  
Fang Zhao ◽  
Qinglian Tang ◽  
Jian Xu ◽  
Shuangyan Wang ◽  
Shaoheng Li ◽  
...  
Keyword(s):  
Neuropathic Pain ◽  
Rat Model ◽  
Analgesic Effect ◽  
Neuronal Excitability ◽  
Active Components ◽  
Action Potential Firing ◽  
Voltage Gated ◽  
Voltage Gated Sodium Channels ◽  
Ic50 Values ◽  
Medical Plant

Picrasma quassioides (D. Don) Benn, a medical plant, is used in clinic to treat inflammation, pain, sore throat, and eczema. The alkaloids are the main active components in P. quassioides. In this study, we examined the analgesic effect of dehydrocrenatidine (DHCT), a β-carboline alkaloid abundantly found in P. quassioides in a neuropathic pain rat model of a sciatic nerve chronic constriction injury. DHCT dose-dependently attenuated the mechanic allodynia. In acutely isolated dorsal root ganglion, DHCT completely suppressed the action potential firing. Further electrophysiological characterization demonstrated that DHCT suppressed both tetrodotoxin-resistant (TTX-R) and sensitive (TTX-S) voltage-gated sodium channel (VGSC) currents with IC50 values of 12.36 μM and 4.87 µM, respectively. DHCT shifted half-maximal voltage (V1/2) of inactivation to hyperpolarizing direction by ~16.7 mV in TTX-S VGSCs. In TTX-R VGSCs, DHCT shifted V1/2 of inactivation voltage to hyperpolarizing direction and V1/2 of activation voltage to more depolarizing potential by ~23.9 mV and ~12.2 mV, respectively. DHCT preferred to interact with an inactivated state of VGSCs and prolonged the repriming time in both TTX-S and TTX-R VGSCs, transiting the channels into a slow inactivated state from a fast inactivated state. Considered together, these data demonstrated that the analgesic effect of DHCT was likely though the inhibition of neuronal excitability.

scholarly journals Purification and Characterization of JZTx-14, a Potent Antagonist of Mammalian and Prokaryotic Voltage-Gated Sodium Channels

Toxins ◽  
2018 ◽  
Vol 10 (10) ◽  
pp. 408 ◽  
Author(s):  
Jie Zhang ◽  
Dongfang Tang ◽  
Shuangyu Liu ◽  
Haoliang Hu ◽  
Songping Liang ◽  
...  
Keyword(s):  
Sodium Channels ◽  
Resting State ◽  
Purification And Characterization ◽  
Voltage Gated ◽  
Voltage Gated Sodium Channels ◽  
Steady State Inactivation ◽  
Ic50 Values ◽  
Gating Modifier ◽  
Potent Antagonist

Exploring the interaction of ligands with voltage-gated sodium channels (NaVs) has advanced our understanding of their pharmacology. Herein, we report the purification and characterization of a novel non-selective mammalian and bacterial NaVs toxin, JZTx-14, from the venom of the spider Chilobrachys jingzhao. This toxin potently inhibited the peak currents of mammalian NaV1.2–1.8 channels and the bacterial NaChBac channel with low IC50 values (<1 µM), and it mainly inhibited the fast inactivation of the NaV1.9 channel. Analysis of NaV1.5/NaV1.9 chimeric channel showed that the NaV1.5 domain II S3–4 loop is involved in toxin association. Kinetics data obtained from studying toxin–NaV1.2 channel interaction showed that JZTx-14 was a gating modifier that possibly trapped the channel in resting state; however, it differed from site 4 toxin HNTx-III by irreversibly blocking NaV currents and showing state-independent binding with the channel. JZTx-14 might stably bind to a conserved toxin pocket deep within the NaV1.2–1.8 domain II voltage sensor regardless of channel conformation change, and its effect on NaVs requires the toxin to trap the S3–4 loop in its resting state. For the NaChBac channel, JZTx-14 positively shifted its conductance-voltage (G–V) and steady-state inactivation relationships. An alanine scan analysis of the NaChBac S3–4 loop revealed that the 108th phenylalanine (F108) was the key residue determining the JZTx-14–NaChBac interaction. In summary, this study provided JZTx-14 with potent but promiscuous inhibitory activity on both the ancestor bacterial NaVs and the highly evolved descendant mammalian NaVs, and it is a useful probe to understand the pharmacology of NaVs.

The Prolonged Analgesic Effect of Epidural Ropivacaine in a Rat Model of Neuropathic Pain

2008 ◽  
Vol 106 (1) ◽  
pp. 313-320 ◽  
Author(s):  
Chiyo Sato ◽  
Atsushi Sakai ◽  
Yumiko Ikeda ◽  
Hidenori Suzuki ◽  
Atsuhiro Sakamoto
Keyword(s):  
Neuropathic Pain ◽  
Rat Model ◽  
Analgesic Effect

scholarly journals Neuropathic Pain Develops Normally in Mice Lacking both Nav1.7 and Nav1.8

2005 ◽  
Vol 1 ◽  
pp. 1744-8069-1-24 ◽  
Author(s):  
Mohammed A Nassar ◽  
Alessandra Levato ◽  
L Caroline Stirling ◽  
John N Wood
Keyword(s):  
Neuropathic Pain ◽  
Sodium Channels ◽  
Sensory Neurons ◽  
Inflammatory Pain ◽  
Pain Thresholds ◽  
Voltage Gated ◽  
Voltage Gated Sodium Channels ◽  
Pain Symptoms ◽  
Α Subunits

Two voltage gated sodium channel α-subunits, Nav1.7 and Nav1.8, are expressed at high levels in nociceptor terminals and have been implicated in the development of inflammatory pain. Mis-expression of voltage-gated sodium channels by damaged sensory neurons has also been implicated in the development of neuropathic pain, but the role of Nav1.7 and Nav1.8 is uncertain. Here we show that deleting Nav1.7 has no effect on the development of neuropathic pain. Double knockouts of both Nav1.7 and Nav1.8 also develop normal levels of neuropathic pain, despite a lack of inflammatory pain symptoms and altered mechanical and thermal acute pain thresholds. These studies demonstrate that, in contrast to the highly significant role for Nav1.7 in determining inflammatory pain thresholds, the development of neuropathic pain does not require the presence of either Nav1.7 or Nav1.8 alone or in combination.

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