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  • Title: Relative potency of synthetic analogs of Ptychodiscus brevis toxin in depressing synaptic transmission evoked in neonatal rat spinal cord in vitro.
    Author: Singh JN, Das Gupta S, Gupta AK, Dube SN, Deshpande SB.
    Journal: Toxicol Lett; 2002 Mar 10; 128(1-3):177-83. PubMed ID: 11869828.
    Abstract:
    Effects of Ptychodiscus brevis toxin (PbTx) analogs on the spinal synaptic transmission in neonatal rats in vitro were evaluated. PbTx1/PbTx2 had aromatic groups and PbTx3/PbTx4 had aliphatic groups. All the analogs depressed monosynaptic reflex (MSR) and polysynaptic reflex (PSR) in a concentration-dependent manner. The maximal depression of MSR (75% from initial) and PSR (96%) was at 84 microM for PbTx1. Concentration to produce 25% inhibition from initial (IC25) by PbTx1 for MSR and PSR was < or =2.8 microM. The maximal depression of MSR (80%) was at 96 microM and PSR (100%) was at 32 microM by PbTx2. IC25 for MSR and PSR were 5.5 microM and <3.2 microM, respectively. PbTx3 decreased MSR by 25% maximally (=IC25) at 36 microM. The depression of PSR fluctuated and was maximal (75%) at 108 microM and IC25 was 6.2 microM. PbTx4 depressed MSR and PSR at the maximum of 35% at 32 microM and IC25 for MSR was 8.3 microM and for PSR was 35 microM. Rank order of potency of toxins for depressing MSR was PbTx1>PbTx2>>PbTx4>PbTx3; and for PSR it was PbTx2>PbTx1>PbTx3>>PbTx4. Results indicate that the toxins having aromatic groups exhibited greater neurotoxicity.
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