Effect of ANEPIII, a novel recombinant neurotoxic polypeptide, on sodium channels in primary cultured rat hippocampal and cortical neurons. Regul Pept

Department of Pharmacology, Shenyang Pharmaceutical University, Shenyang 110016, PR China.
Regulatory Peptides (Impact Factor: 1.83). 09/2010; 164(2-3):105-12. DOI: 10.1016/j.regpep.2010.05.010
Source: PubMed


Previous studies have shown that the recombinant neurotoxic polypeptide BmK ANEP (ANEPIII) displayed good anti-neuroexcitation activity as demonstrated by pharmacological tests of the blockade of chemical-induced convulsive seizures. In order to search for further anticonvulsant mechanism of action of ANEPIII, the effects of ANEPIII on sodium channels were assessed using the whole-cell patch clamp recordings in primary cultures of rat hippocampal and cortical neurons. ANEPIII decreased the sodium currents in a voltage-dependent manner, which appeared as a shift of the current-voltage relation to positive potentials. The effect was reversible after washing. The concentration-responsiveness measured in hippocampal and cortical neurons revealed an IC(50) value of 124.6 nM and 192.7 nM, respectively. Furthermore, ANEPIII 1000 nM significantly shifted the activation curves of sodium current in hippocampal and cortical neurons to more positive potentials and the recovery from inactivation of sodium current was significantly slower. Voltage-dependent inactivation curves of sodium channels in hippocampal and cortical neurons did not change in the presence of 1000 nM ANEPIII. Thus, our results demonstrated that ANEPIII in submicromolar concentrations was a voltage-dependent, reversible blocker of sodium current in hippocampal and cortical neurons. It is concluded that these phenomena may explain, at least in part, the anti-neuroexciting properties of this peptide.

7 Reads
  • Source
    • "Recording electrodes were filled with an internal solution containing (in mM): 140 CsCl, 10 EGTA, 0.1 CaCl 2 , 2 MgCl 2 , 10 HEPES, 2 ATP, and pH 7.2 adjusted with Tris. Patch-clamp electrodes were pulled with a P-97 puller, and had a resistance of 3–5 MX [25]. Peak current amplitudes were measured before and after a 3–5-min incubation with AGAP. "
    [Show abstract] [Hide abstract]
    ABSTRACT: A previous study showed that antitumor-analgesic peptide (AGAP), a novel recombinant polypeptide, which had been expressed in Escherichia coli, exhibits analgesic and antitumor effects in mice. In the present study, we investigated the underlying analgesic mechanism of AGAP. The effect of AGAP on voltage-gated calcium channels (VGCCs) was assessed in acutely isolated rat dorsal root ganglia (DRG) neurons using the whole-cell patch clamp technique. The results showed that AGAP potently inhibited VGCCs, especially high-voltage activated (HVA) calcium channels. AGAP inhibited HVA and T-type calcium currents in a dose-dependent manner, but had no significant effect on their dynamic functions in rat small-diameter DRG neurons. AGAP inhibited N- and L-type calcium currents at 78.2% and 57.3%, respectively. Thus, the present study demonstrates that AGAP affects calcium currents through the inhibition of N-, L- and T-type channels in DRG neurons, explaining the potential mechanisms of antinociception.
    Preview · Article · Sep 2014 · Biochemical and Biophysical Research Communications
  • Source
    • "VGCCs and subsequently modulate the Ca 2+ entry into neurons. The facilitation of Ca 2+ entries into nerve terminals by modulating the opening of VGCCs may further increase the amount of the released excitatory amino acids, which increase the excitability of the neurons (Li et al., 2010). There is a residual after-effect of consecutive daily applications of rTMS. "
    [Show abstract] [Hide abstract]
    ABSTRACT: Repetitive transcranial magnetic stimulation (rTMS) is able to induce alteration in cortical activity and excitability that outlast the period of stimulation, which is long-term depression (LTD) or long-term potentiation (LTP)-like. Accumulating evidence shows that Na(+), Ca(2+) and K(+) channels are important for the regulation of neuronal excitability. To investigate the possible mechanisms of rTMS on regulation of intrinsic excitability in hippocampal neurons, the male or female Sprague-Dawley rats aged 2-3 days or 7-8 days were treated with 14 or 7-day's low frequency (1Hz) rTMS (400 stimuli/day), respectively. After that, the effects of rTMS on ion channels such as: Na(+)-channel, A-type K(+)-channel and Ca(2+)-channel in rat hippocampal CA1 pyramidal neurons were performed by standard whole-cell patch-clamp technique. The results showed that the peak amplitude and maximal rise slope of evoked single action potential (AP) were significantly increased after 14-day's rTMS treatment. Meanwhile, the AP threshold was significantly more depolarized in neurons after 14-day's rTMS treatment than neurons in control group that without rTMS treatment. The spontaneous excitatory post-synaptic currents (sEPSCs) frequency and amplitude of CA1 pyramidal neurons in groups with rTMS treatment (both 7d and 14d) were obviously increased compared with the age-matched control group. Furthermore, we found that electrophysiological properties of Na(+)-channel were markedly changed after rTMS treatment, including negative-shifted activation and inactivation curves, as well as fasten recovery rate. After rTMS application, the IA amplitude of K(+)-channel was reduced; the activation and inactivation curves of K(+)-channel were significantly shifted to right. Time constant of recovery from inactivation was also more rapid. Moreover, rTMS induced an obvious increment in the maximal current peak amplitude of Ca(2+)-channel. At the same time, there was a significant rightward shift in the activation curve and inactivation curves of Ca(2+)-channel. These data suggest that rTMS can enhance the AP and sEPSCs of hippocampal CA1 neurons. Altered electrophysiological properties of Na(+)-channel, A-type K(+) channels and Ca(2+) channels contribute to the underling mechanisms of rTMS-induced up-regulation of neural excitability.
    Full-text · Article · May 2013 · Brain research
  • [Show abstract] [Hide abstract]
    ABSTRACT: Drug molecules which can block the function of ion channels are important in the treatment of several disorders which are all generally characterized by abnormal membrane excitability, that is autoimmune disorders, hypertension, cardiac arrhythmias and heart failure, Alzheimer’s as well as Parkinson’s diseases, and many others. Molecular Docking, Molecular Dynamics simulations, quantum chemical calculations, QM/MM calculations and 2D-, 3D- and 4D-QSAR, ADMET prediction have been widely used to drug discovery. In this article, we have highlighted the most recent applications of molecular modeling techniques to ion channels blockers and given the perspective.
    No preview · Chapter · Jan 2011