Document Detail

Ptychodiscus brevis toxin-induced depression of spinal reflexes involves 5-HT via 5-HT3 receptors modulated by NMDA receptor.
MedLine Citation:
PMID:  17014958     Owner:  NLM     Status:  MEDLINE    
The involvement of 5-hydroxytryptaminergic (5-HT) system for the Ptychodiscus brevis toxin (PbTx)-induced depression of spinal reflexes was evaluated. The reflex potentials were recorded at ventral root by stimulating the corresponding dorsal root in neonatal rat spinal cord in vitro. Superfusion of PbTx (2.8-84microM) depressed the monosynaptic (MSR) and polysynaptic (PSR) reflexes in a concentration-dependent manner. The depression of the reflexes was maximal with 84microM of the toxin. Ondansetron (0.1microM), a 5-HT(3) receptor antagonist, blocked the PbTx-induced depression of MSR and PSR. Spiperone (a 5-HT(2A) antagonist) or ketanserin (5-HT(2A/2C) antagonist and also at 5-HT(1B/1D)) failed to block the PbTx-induced depression of the reflexes. The 5-HT concentration of the cords was increased by four-fold after exposure to PbTx (28microM) and the increase was not seen in the cords pretreated with dl-2 amino-5-phosphonovaleric acid (APV, a NMDA receptor antagonist). Superfusion of 5-HT or phenylbiguanide (PBG, a 5-HT(3) receptor agonist) also produced depression of the spinal reflexes in a concentration-dependent manner. The 5-HT-induced depression of reflexes was blocked by ondansetron but not by spiperone. The results demonstrate that the PbTx-induced depression of spinal reflexes involves 5-hydroxytryptamine via 5-HT(3) receptors modulated by NMDA receptor.
Jitendra N Singh; Rajesh Gupta; Shripad B Deshpande
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't     Date:  2006-10-02
Journal Detail:
Title:  Neuroscience letters     Volume:  409     ISSN:  0304-3940     ISO Abbreviation:  Neurosci. Lett.     Publication Date:  2006 Nov 
Date Detail:
Created Date:  2006-10-24     Completed Date:  2007-01-04     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  7600130     Medline TA:  Neurosci Lett     Country:  Ireland    
Other Details:
Languages:  eng     Pagination:  70-4     Citation Subset:  IM    
Department of Physiology, Institute of Medical Sciences, Banaras Hindu University, Varanasi 221005, India.
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MeSH Terms
Biguanides / pharmacology
Depression, Chemical
Dinoflagellida / chemistry*
Dopamine Antagonists / pharmacology
Dose-Response Relationship, Drug
Ketanserin / pharmacology
Marine Toxins / toxicity*
Neurotoxins / toxicity*
Ondansetron / pharmacology
Receptors, N-Methyl-D-Aspartate / drug effects,  physiology*
Receptors, Serotonin, 5-HT3 / drug effects,  physiology*
Reflex / drug effects*
Serotonin / physiology*
Serotonin Antagonists / pharmacology
Spinal Cord / drug effects,  metabolism
Spinal Nerve Roots / physiology
Spiperone / pharmacology
Reg. No./Substance:
0/Biguanides; 0/Dopamine Antagonists; 0/Marine Toxins; 0/Neurotoxins; 0/Ptychodiscus brevis T2 toxin; 0/Receptors, N-Methyl-D-Aspartate; 0/Receptors, Serotonin, 5-HT3; 0/Serotonin Antagonists; 102-02-3/phenyl biguanide; 50-67-9/Serotonin; 74050-98-9/Ketanserin; 749-02-0/Spiperone; 99614-02-5/Ondansetron

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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