title: Venom from Anemesia species of spider modulates high voltage-activated Ca(2+) currents from rat cultured sensory neurones and excitatory post synaptic currents from rat hippocampal slices.
abstract: The actions of crude venom from Anemesia species of spider were investigated in cultured dorsal root ganglion neurones from neonatal rats and hippocampal slices. Using mass spectrometry (MALDI-TOF MS), 10-12 distinct peptides with masses between about 3 and 10kDa were identified in the crude spider venom. At a concentration of 5 microg/ml crude Anemesia venom transiently enhanced the mean peak whole cell voltage-activated Ca(2+) current in a voltage-dependent manner and potentiated transient increases in intracellular Ca(2+) triggered by 30mM KCI as measured using Fura-2 fluorescence imaging. Additionally, 5-8 microg/ml Anemesia venom increased the amplitude of glutamatergic excitatory postsynaptic currents evoked in hippocampal slices. Omega-Conotoxin GVIA (1 microM) prevented the increase in voltage-activated Ca(2+) currents produced by Anemesia venom. This attenuation occurred when the cone shell toxin was applied before or after the spider venom. Anemesia venom (5 microg/ml) created no significant change in evoked action potentials but produced modest but significant inhibition of voltage-activated K(+) currents. At a concentration of 50 microg/ml Anemesia venom only produced reversible inhibitory effects, decreasing voltage-activated Ca(2+) currents. However, no significant effects on Ca(2+) currents were observed with a concentration of 0.5 microg/ml. The toxin(s) in the venom that enhanced Ca(2+) influx into sensory neurones was heat-sensitive and was made inactive by boiling or repetitive freeze-thawing. Boiled venom (5 microg/ml) produced significant inhibition of voltage-activated Ca(2+) currents and freeze-thawed venom inhibited Ca(2+) transients measured using Fura-2 fluorescence. Our data suggest that crude Anemesia venom contains components, which increased neuronal excitability and neurotransmission, at least in part this was mediated by enhancing Ca(2+) influx through N-type voltage-activated Ca(2+) channels.
authors.affiliation: Uzbek Academy of Science, Institute of Physiology & Biophysics, Tashkent, Uzbekistan.
authors.forename: D
authors.initials: D
authors.lastname: Kalikulov
authors.forename: A
authors.initials: A
authors.lastname: Ayar
authors.forename: F
authors.initials: F
authors.lastname: Nuritova
authors.forename: B G
authors.initials: BG
authors.lastname: Frenguelli
authors.forename: D
authors.initials: D
authors.lastname: McClelland
authors.forename: D J
authors.initials: DJ
authors.lastname: Martin
authors.forename: I
authors.initials: I
authors.lastname: Davidson
authors.forename: R H
authors.initials: RH
authors.lastname: Scott
mesh_terms: D000200:Action Potentials / Q000187:drug effects; D000818:Animals; D002118:Calcium / Q000378:metabolism*; D015220:Calcium Channels / Q000378:metabolism; D002478:Cells, Cultured; D004553:Electric Conductivity; D019706:Excitatory Postsynaptic Potentials / Q000187:drug effects*; D005260:Female; D005453:Fluorescence; D005727:Ganglia, Spinal / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D006624:Hippocampus / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D066298:In Vitro Techniques; D008297:Male; D009475:Neurons, Afferent / Q000187:drug effects* / Q000378:metabolism*; D018408:Patch-Clamp Techniques; D011188:Potassium / Q000378:metabolism / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley; D013111:Spider Venoms / Q000494:pharmacology*; D013112:Spiders; D013997:Time Factors
chemical_list: D015220:Calcium Channels; D013111:Spider Venoms; D011188:Potassium; D002118:Calcium