1. G Model
NEUTOX-899; No of Pages 6
NeuroToxicology xxx (2008) xxx–xxx
Contents lists available at ScienceDirect
NeuroToxicology
Brief communication
Synaptic effects of low molecular weight components from Chilean Black
Widow spider venom
Jorge Parodi *, Fernando Romero
Laboratorio de Neurociencia-CEBIOR, Departamento de Ciencia Preclinicas, Facultad de Medicina, Universidad de la Frontera, Montevideo 0870, Temuco, Chile
A R T I C L E I N F O A B S T R A C T
Article history: a-Latrotoxin is the principal component of the venom from the euroasiatic Black Widow spider and has
Received 23 May 2008 been studied for its pharmacological use as a synaptic modulator. Interestingly, smaller molecular weight
Accepted 27 August 2008 fractions have been found to be associated with this toxin, but their cellular actions have not been studied
Available online xxx
in detail. The venom from the Chilean Black Widow spider (Latrodectus mactans) does not produce a-
latrotoxin, however it does contain several small polypeptides. We have recently demonstrated cellular
Keywords: effects of these peptides at the synaptic level using whole-cell patch clamp techniques. Purified venom
Synapses
from the glands of L. mactans was studied in 12 DIV rat hippocampal neuronal cultures. Venom at a
Venom
concentration of 10 nM was able to decrease neuronal conductance thereby increasing membrane
Spider
Toxic resistance. This effect on the passive properties of the neurons induced a change in action potential
Black Widow kinetics simulating the action of classic potassium channel blockers. These changes produced an increase
in spontaneous synaptic activity in rat hippocampal cultures in the presence of the venom in a
concentration- and time-dependent manner. These results indicate that venom from Chilean spider L.
mactans is capable of increasing cell membrane resistance, prolonging the action potential and
generating an increase in synaptic activity demonstrating an interesting pharmacological effect of these
low molecular weight fragments.
ß 2008 Elsevier Inc. All rights reserved.
1. Introduction cholinergic mediators (patent pending). These results raise ques-
tions about the mechanism of action of the toxin on smooth muscle.
The Chilean spider Latrodectus mactans pertains to the genus We postulated ionic mechanism, to explain same of these systemic
Latrodectus which is found worldwide (Garb et al., 2004) and is effects, based in the idea of described effects of low-molecular
known as the ‘‘Wheat Spider’’ or ‘‘Black Widow’’ and inhabits component from Black Widow venom, over muscle and alteration
various regions of Chile. The bite from this spider in humans the cellular physiology (Kiyatkin et al., 1992; Grishin et al., 1993). It
produces a systemic effect called latrodectism or systemic has been postulated that potassium currents, for the importance of
latrodectism and in some cases results in death (Schenone and these currents in the regulation of muscle contraction and the
Correa, 1985). participation over calcium homeostatic (Sanborn, 2000). A classic
Venom collected from Chilean L. mactans in the VIII and IX regions synaptic model was affects for a-latrotoxin and high-molecular
of Chile was shown to induce a sustained tonic effect in cardiac and weight peptides (Auger and Marty, 2000) and dependent of
smooth muscle (Romero et al., 2003). In smooth muscle, the potassium channels for normal regulation of synaptic activity
mechanism of contraction is related to the permeability of Na+ and (Pan and Stringer, 1997). We tested the effect of Chilean venom in
Ca2+ ions which modulate the contractile response (Nouailhetas hippocampal neuron, and reported the changes in synaptic activity,
et al., 1985) that has a fast, phasic component followed by a slower for have synaptic effects under control and postulate, mechanism
more sustained tonic component (Shimuta et al., 1982). Our studies over neuromuscular union. For another way, we choice a basic
in the deferent vessel of the rat revealed that the effect induced model of cell lines, for observation of passive electric properties of
by the L. mactans venom is partially dependent of adrenergic and membrane and not showed receptor or increased number of
channels (Varghese et al., 2006). For these reason used HEK 293 cells
for the observation of changes in membranes conductance. In the
present study was to analyze the possible participation of potassium
* Corresponding author at: Laboratorio de Neurociencia-CEBIOR, Facultad de
Medicina, Universidad de la Frontera, Montevideo 0870, Temuco, Chile.
conductance on the systemic effects observed with the venom of L.
Tel.: +56 45 734041. mactans, recording cellular effects associated a changes in potassium
E-mail address: jparodi@ufro.cl (J. Parodi). conductance in neurons and cells lines.
0161-813X/$ – see front matter ß 2008 Elsevier Inc. All rights reserved.
doi:10.1016/j.neuro.2008.08.006
Please cite this article in press as: Parodi J, Romero F. Synaptic effects of low molecular weight components from Chilean Black Widow
spider venom, Neurotoxicology (2008), doi:10.1016/j.neuro.2008.08.006

2. G Model
NEUTOX-899; No of Pages 6
2 J. Parodi, F. Romero / NeuroToxicology xxx (2008) xxx–xxx
2. Materials and methods scope (Nikon, Eclipse, TE200-u, Japan). The membrane potential
was adjusted to À60 mV, the current recorded at 50 ms intervals
2.1. Spider retrieval and filtered at 2 kHz using commercially available software (Axon
Instruments, Inc.). Tetrodotoxin (TTX, 100 nM), a Na+ voltage-
Female adult L. mactans spiders from Chile were captured dependent channel blocker, was added to the external solution to
during the summer months (December 2005 and January 2006) block excessive synaptic activity evoked by action potentials
from the area of Alto Bio in the VIII region (728160 5100 W, 78450 2400 S) thereby allowing the visualization of miniature synaptic currents
as previously described, taking care not to damage breeding zones (mIPSCs and mEPSCs). The patch electrodes were made of
(Romero et al., 2003). The specimens were maintained separate in borosilicate (WPI, Sarasota, USA) and prepared using a horizontal
individual jars for 30 days without food and given only water in pipette puller (Sutter Instruments, USA). The resistance of the
order to stimulate the production and concentration of venom in electrodes was less than 4 MV when filled with normal internal
the glands. solution.
Stock solutions for assays containing pharmacological com-
2.2. Venom retrieval pounds, drugs or different ligands were prepared weekly in
deionized distilled water and kept at 4 8C. For fast application of
The spiders were immersed in liquid nitrogen and after 1 min different compounds, a system of external tubes (200 mm internal
transferred to a phosphate saline buffer solution (PBS: NaH2PO4 diameter) situated 50 mm from the cells was used. Electrophysio-
0.1 M, Na2HPO4 0.01 M, NaCl 1.35 M, pH 7.4) at 4 8C. The glands logical recordings were done in the presence and absence of different
were removed and the membrane that binds them to the base was drugs, pharmacological compounds and ions. The solutions contain-
sectioned. Each glands with its poison secreting, was placed into a ing the different compounds flowed continuously from the inside of
tube containing PBS (25 pairs of glands for 100 ml of PBS) and the tubes by gravity and locally bathed the cell under study.
homogenized. The homogenate was immediately centrifuged at Neuronal recordings were done in the presence or absence of TTX
1000 Â g for 15 min and the supernatant was subsequently (100 nM) depending on whether the desired information was for
aliquoted, labeled total venom (TV) and frozen at À20 8C. The miniature currents or potential action recording, respectively.
protein content of the TV was measured using the Bradford
technique, with small modifications (BioRad Protein Assay). 2.6. Data analyse
2.3. Neuronal cultures The recordings were obtained in pClamp 9 from axon
instrument. The graphic was made using Origin 6 or prism 4, for
The animals were treated and handled according to NIH statistic analyze used Origin 6. The plotted are means Æ S.E. For
guidelines (National Institute of Health, USA). Timed (18 days) p < 0.05 the means are considered significant.
pregnant Sprague–Dawley rats were anaesthetized with ether and
euthanized by cervical dislocation. The embryos were quickly 3. Results
removed, decapitated and the brains placed in cold Hank’s
solution. Subsequently, the hippocampi were dissected; mechani- 3.1. Total venom alters cell membrane conductance
cally dissociated using trypsin, collagenase and DNase III and the
neurons were then plated at a density of 350,000 cells/ml onto Previous reports have shown that total venom from the Chilean
35 mm culture plates containing a monolayer of glia cells. Neurons L. mactans spider is capable of altering normal processes in isolated
were maintained in culture for 12 days in vitro (DIV) at which point organs (Romero et al., 2003; Romero et al., 2007). These effects
they were used for experiments. The culture media consisted of have been reported as secondary to the action of the venom on
80% MEM, 2 mM glutamine, and 10% fetal bovine serum. The media ionic channels and proton pumps such as the sodium/potassium
was replaced with fresh culture media every 3 days. All drugs, exchanger (Robello, 1989; Chanturiya and Nikoloshina, 1994). It is
pharmacological compounds and ions used in the different noteworthy that the Chilean species, although having similar toxic
experimental protocols were diluted in PBS buffer. effects, lacks the a-latrotoxin characteristic of the venom. We
decided to investigate if there was a mechanism which would
2.4. Cell cultures explain the changes at the isolated organ level that was related to
some of the ionic alterations previously described. Therefore, we
HEK Cells 293 (human embryonic kidney cells) are cultivated in studied the effect of extracellular application of TV from L. mactans
D-MEM (Dulbecco’s-modified Eagle medium, Life Technologies, in HEK 293 cells. Voltage–current curves for membrane con-
Inc.) supplemented by 10% of fetal bovine serum (Life Technologies ductance were performed, in voltage clamp mode, used a
Inc.) and streptomicina–penicillin (200 units each, Life Technol- depolarization protocol from À60 to 160 mV on HEK cells in the
ogies Inc). Growth is carried out fewer than 5% CO2 to 37 8C. The presence and absence of TV. Fig. 1 shows that HEK cells incubated
medium is changed every 3 days. 30 min with TV present a decrease in the slope, for a conductance
graph (Voltage vs. current plot) indicating an increase in
2.5. Whole-cell patch clamp membrane resistance (the inverses of conductance for this graph)
as compared with control. This finding suggests the possibility of
The culture media in the plate was replaced with an external ionic channel closure producing an increase in membrane
solution containing (in mM): 150 NaCl, 5.4 KCl, 2.0 CaCl2, 1.0 resistance or reduced the conductance (slope of the plot). To find
MgCl2, 10 glucose and 10 HEPES (pH 7.4). The internal solution out if this observation was reproducible with other known
contained (in mM): 120 KCl, 2.0 MgCl2, 2 ATP-Na2, 10 BAPTA, 0.5 molecules, we used the same protocol in cells cultured with TEA
GTP, 10 HEPES (pH 7.4). The cells were stabilized at 22 8C for (a potassium channel blocker) or with gramicidin, an agent known
30 min before starting the experiments. Current changes in the to perforate membranes (i.e. increase in conductance). Fig. 1B
neurons were detected using the whole-cell patch clamp demonstrates that both compounds vary the slope of the curves as
technique (Hamill et al., 1981) with an Axopatch-200B amplifier compared to control. Interestingly, the channel blocker TEA had a
(Axon Instruments, Inc., Burlingame, CA) and an inverted micro- similar effect as that observed with TV. The graph in Fig. 1C
Please cite this article in press as: Parodi J, Romero F. Synaptic effects of low molecular weight components from Chilean Black Widow
spider venom, Neurotoxicology (2008), doi:10.1016/j.neuro.2008.08.006

3. G Model
NEUTOX-899; No of Pages 6
J. Parodi, F. Romero / NeuroToxicology xxx (2008) xxx–xxx 3
Fig. 1. Effects of Chilean Latrodectus mactans venom extract on membrane conductance. The data were obtained from HEK 293 cells. The cultures were exposed to chronic
treatment with Chilean Latrodectus mactans venom extract (7.5 mg/ml, 30 min). (A) Shows an I–y relationship in absence or presence of venom. (B) Shows I–y curves that
compare the effects of gramicidin (10 mg/ml) and TEA (100 nM) with the venom. (C) Shows values for membrane resistance in the absence and presence of venom. The bars
are mean Æ S.E. from 16 different cells (*p < 0.05).
demonstrates the membrane resistance in the absence and 3.3. TV increases synaptic transmission in cultured hippocampal
presence of the venom. Cells exposed in acute manner with TV neurons
showed a significant increase in membrane resistance.
As previously mentioned, a-latrotoxin is capable of altering
3.2. Latrodectus venom alters membrane and action potentials in synaptic activity, however smaller peptides appear to have a
hippocampal neurons complementary effect. Our results suggest that in the absence of a-
latrotoxin, such as in our Chilean L. mactans model, the smaller
The effects of a-latrotoxin in the synapse has been described by fragments play an active role in producing the effect seen with the
several investigators; however the mechanism by which the venom. This is in agreement with the systemic effects observed with
venom induces changes is still unclear. It is currently accepted that the venom from Chilean L. mactans (Romero et al., 2003; Romero
the interaction of a-latrotoxin with cell membranes (Krasilnikov et al., 2007) as well as with experiments in isolated organs (Romero
and Sabirov, 1992; Orlova et al., 2000; Hlubek et al., 2003) results et al., 2003). Fig. 3A shows representative traces of synaptic activity
in the formation of a pore permeable to calcium and this is the in the absence or presence of TV. Neurons cultured in the presence of
mechanism by which the venom alters synaptic activity (Henkel TV display a significant increase in synaptic events. Interestingly,
and Sankaranarayanan, 1999). The presence of other small- denatured venom, boiled for 45 min at 96 8C, has no effect on the
molecular weight molecules having a synergistic action have been neurons indicating a specific participation of the peptides present in
described (Kiyatkin et al., 1992; Grishin et al., 1993). Our results, the venom (Fig. 3B). Fig. 3C and D reveal a time- and concentration-
however, suggest that the fragments we studied are capable of dependent action of TV as reflected in an increase in the frequency of
altering the normal functioning of isolated organs and could be events with longer incubation times and higher concentrations of
modifying membrane conductance. Fig. 2A shows representative the venom. Both figure, suggested a pharmacology effects over the
traces of action potentials from hippocampal neurons in the synapses, because induced to think a time depend effects and
absence or presence of TEA and TV. The traces indicate that TEA concentration response, two characteristic of physiological effect
alters the action potential, lengthening the repolarization phase over receptors or protein. In addition, Fig. 3C demonstrates that
(Schwartzkroin and Prince, 1980) which is mediated by potassium these effects are reversible because when the venom is removed, the
channels (Woodson et al., 1978). The venom is also able to alter the synaptic frequency returns to control levels. On the contrary, higher
action potential kinetics in a manner parallel to TEA suggesting concentrations of the venom are unable to alter synaptic activity
similar mechanisms. Fig. 2B current clamp traces, acquired in the suggesting an antagonistic effect (Fig. 3D), not explored but the
presence of TTX (100 nM) for prevented potential action, from interesting in biotechnology application. Therefore, we can suggest
neurons exposed to TEA or TV. As can be seen, TEA produces a that the alteration in synaptic activity in the presence of the venom
lengthening on the action potential, a similar effect found with TV. may be due to blockage of potassium channels, similar to TEA
Fig. 2C shows the change in membrane potential, acquired using sensible and changes in membrane potential.
current clamp, for measured the changes in the potential and Noteworthy, TV from L. mactans has demonstrated to be a
reveals that both TEA and TV significantly decrease the membrane potent stimulator of synaptic activity in cultured hippocampal
potential to values near the action potential threshold. These data neurons despite the fact that it lacks latrotoxin. Therefore, our data
demonstrate a change in the passive properties of the membranes provides the first evidence that polypeptides present in L. mactans
in the presence of TV, similar to TEA, indicating the closing of alter synaptic activity in a manner similar to a-latrotoxin, but for a
potassium channels. different mechanism.
Please cite this article in press as: Parodi J, Romero F. Synaptic effects of low molecular weight components from Chilean Black Widow
spider venom, Neurotoxicology (2008), doi:10.1016/j.neuro.2008.08.006

4. G Model
NEUTOX-899; No of Pages 6
4 J. Parodi, F. Romero / NeuroToxicology xxx (2008) xxx–xxx
Fig. 2. Effects of Chilean Latrodectus mactans venom extract on membrane potential from hippocampal neurons. The data were obtained from 12 DIV neurons exposed to acute
applications of Chilean Latrodectus mactans venom extract (7.5 mg/ml). (A) Shows action potential traces, in the absence and presence of TEA (100 nM) or venom (7.5 mg/ml).
(B) Shows membrane potential traces, with TTX (100 nM) in absence and presence of venom. (C) Graph showing membrane resistance values in the absence and presence of
venom. The bars are mean Æ S.E. from eight different neurons (*p < 0.05).
Fig. 3. Effects of Chilean Latrodectus mactans venom extract on synaptic activity. The data were obtained from 12 DIV neurons exposed to acute applications of Chilean
Latrodectus mactans venom extract (7.5 mg/ml). (A) Shows synaptic currents obtained in the absence and presence of venom or boiled venom. (B) Shows miniature synaptic
current frequency in the presence of the venom. (C) Graph of synaptic frequency at different times incubation and (D) data showing the effect of different concentrations of
the venom. The bars are mean Æ S.E. from 19 different neurons (*p < 0.05).
4. Discussion described a fractionation of the venom by HPLC–MS, and we found
the absence of the higher weight component, like a-latrotoxin, this
Previous report, in our laboratory and work for development a toxin, is the principal component in Black Widow venom and
patent (Under way in countries PCT) was provide information explain mostly of systemic effect secondary to this venom. A few
about the component of the Chilean venom, form L. mactans. We report, do it description of the low weight component, present in
Please cite this article in press as: Parodi J, Romero F. Synaptic effects of low molecular weight components from Chilean Black Widow
spider venom, Neurotoxicology (2008), doi:10.1016/j.neuro.2008.08.006

5. G Model
NEUTOX-899; No of Pages 6
J. Parodi, F. Romero / NeuroToxicology xxx (2008) xxx–xxx 5
the venom but not explored. The Chilean venom, not presents Conflict of interest: Patent pending.
higher component (minor to 10 kDa, data not show) but, the Funding source: FONDEF-D02I1024 and FONDEF-D05I10416.
Chilean venom can induce similar effects to another Black Widow
venom in absence of a-latrotoxin. Agreement with previous
References
studies (Romero et al., 2003, 2007), our data show that
polypeptides present in the venom from Chilean Lactrodectus Ashton AC, Volynski KE, Lelianova VG, Orlova EV, Van Renterghem C, Canepari M, et al.
mactans spiders increase spontaneous synaptic activity in hippo- Alpha-latrotoxin, acting via two Ca2+-dependent pathways, triggers exocytosis of
campal neurons and changes the passive properties of the two pools of synaptic vesicles. J Biol Chem 2001;276:44695–703.
Auger C, Marty A. Quantal currents at single-site central synapses. J Physiol
membrane, cells lines. 2000;526(Pt 1):3–11.
We suggested, potassium current, for the importance of this Baba A, Yasui T, Fujisawa S, Yamada RX, Yamada MK, Nishiyama N, et al. Activity-
current over membrane potential (Gutman et al., 2003) and the evoked capacitative Ca2+ entry: implications in synaptic plasticity. J Neurosci
2003;23:7737–41.
control in the synaptic activity (Dodson and Forsythe, 2004; Yuan
Chanturiya AN, Nikoloshina HV. Correlations between changes in membrane
and Chen, 2006). Work by Grider and Makhlouf (1988) demon- capacitance induced by changes in ionic environment and the conductance
strated that the tonic response in smooth muscle is dependent on of channels incorporated into bilayer lipid membranes. J Membr Biol
the influx of calcium into the cell. Similarly, synaptic activity is 1994;137:71–7.
Charlton MP, Smith SJ, Zucker RS. Role of presynaptic calcium ions and channels in
dependent on calcium homeostasis in the presynaptic button synaptic facilitation and depression at the squid giant synapse. J Physiol
(Cousin and Robinson, 2000). Therefore, the neuronal response 1982;323:173–93.
observed in the presence of total venom could be related to calcium Cousin MA, Robinson PJ. Ca(2+) influx inhibits dynamin and arrests synaptic vesicle
endocytosis at the active zone. J Neurosci 2000;20:949–57.
influx as a result of the change in membrane potential, secondary Darblade B, Behr-Roussel D, Oger S, Hieble JP, Lebret T, Gorny D, et al. Effects of
effect over calcium, for regulation of potassium channels (Pan and potassium channel modulators on human detrusor smooth muscle myogenic
Stringer, 1997; Yuan and Chen, 2006) (Fig. 2). phasic contractile activity: potential therapeutic targets for overactive bladder.
Urology 2006;68:442–8.
Studies done in isolated organ models determined that Dodson PD, Forsythe ID. Presynaptic K+ channels: electrifying regulators of synaptic
increased muscle contractility is due to changes in ionic con- terminal excitability. Trends Neurosci 2004;27:210–7.
ductance, for example potassium current (Doi et al., 2000; Doi S, Damron DS, Ogawa K, Tanaka S, Horibe M, Murray PA. K(+) channel
inhibition, calcium signaling, and vasomotor tone in canine pulmonary
Darblade et al., 2006). However, we have not described particular artery smooth muscle. Am J Physiol Lung Cell Mol Physiol 2000;279:
potassium current. Was explored the evidence of the activation L242–251.
or modulation of channels and the relation with another effects Garb JE, Gonzalez A, Gillespie RG. The Black Widow spider genus Latrodectus (Araneae:
Theridiidae): phylogeny, biogeography, and invasion history. Mol Phylogenet Evol
of the TV. The presences of Kv1.1 in the models used, are
2004;31:1127–42.
important suggested, because these channels are blocked by TEA Grider JR, Makhlouf GM. Contraction mediated by Ca++ release in circular and Ca++
and this channels are important regulator of membrane potential influx in longitudinal intestinal muscle cells. J Pharmacol Exp Ther 1988;244:
(Gutman et al., 2003). All this is in relation with our data, when 432–7.
Grishin EV, Himmelreich NH, Pluzhnikov KA, Pozdnyakova NG, Storchak LG, Volkova
showed changes in membrane conductance in the presence of TM, et al. Modulation of functional activities of the neurotoxin from Black Widow
the venom and TEA (Fig. 1) most likely due to alterations in the spider venom. FEBS Lett 1993;336:205–7.
TEA sensible conductances (Fig. 2). This finding is important Gutman GA, Chandy KG, Adelman JP, Aiyar J, Bayliss DA, Clapham DE, et al. Interna-
tional Union of Pharmacology. XLI. Compendium of voltage-gated ion channels:
since influx of calcium into the synaptic button occurs due to a potassium channels. Pharmacol Rev 2003;55:583–6.
change in membrane potential that can be regulated by Hamill OP, Marty A, Neher E, Sakmann B, Sigworth FJ. Improved patch-clamp tech-
potassium currents (Charlton et al., 1982; Baba et al., 2003). In niques for high-resolution current recording from cells and cell-free membrane
¨
patches. Pflugers Arch 1981;391:85–100.
addition, voltage-dependent calcium channels are sensitive to Henkel AW, Sankaranarayanan S. Mechanisms of alpha-latrotoxin action. Cell Tissue
variations in voltage resulting in either a higher or lower synaptic Res 1999;296:229–33.
activity (Parker, 2000). Hlubek M, Tian D, Stuenkel EL. Mechanism of alpha-latrotoxin action at nerve endings
of neurohypophysis. Brain Res 2003;992:30–42.
However, it is important to recognize that in the classic model Kiyatkin N, Dulubova I, Chekhovskaya I, Lipkin A, Grishin E. Structure of the low-
for the venom from this species of spider, a-latrotoxin is molecular weight protein copurified with alpha-latrotoxin. Toxicon 1992;30:
responsible for depleting synaptic vesicles (Ashton et al., 2001) 771–4.
Krasilnikov OV, Sabirov RZ. Comparative analysis of latrotoxin channels of different
by disregulating calcium influx and increasing synaptic activity
conductance in planar lipid bilayers. Evidence for cluster organization. Biochim
(Scheer et al., 1985; Magazanik et al., 1992) We did not study if Biophys Acta 1992;1112:124–8.
these effects are reproducible with the venom from L. mactans, Magazanik LG, Fedorova IM, Kovalevskaya GI, Pashkov VN, Bulgakov OV, Grishin EV.
however we postulate a new effect of small molecular weight Selective presynaptic insectotoxin (alpha-latroinsectotoxin) isolated from Black
Widow spider venom. Neuroscience 1992;46:181–8.
peptides presents in this venom. We suggested, channels Nouailhetas VL, Shimuta SI, Paiva AC, Paiva TB. Calcium and sodium dependence of the
modulation for induce changes describes pervious in our biphasic response of the guinea-pig ileum to agonists. Eur J Pharmacol
laboratory and possible to think in a potassium channels, for 1985;116:41–7.
Orlova EV, Rahman MA, Gowen B, Volynski KE, Ashton AC, Manser C, et al. Structure of
explain some of the effects describes or conductances sensible to alpha-latrotoxin oligomers reveals that divalent cation-dependent tetramers form
TEA. More research is needed to study the chronic effects of these membrane pores. Nat Struct Biol 2000;7:48–53.
peptides in order to better understand the systemic effects Pan E, Stringer JL. Role of potassium and calcium in the generation of cellular bursts in
the dentate gyrus. J Neurophysiol 1997;77:2293–9.
produced by the venom in the spider L. mactans from Chile and Parker D. Activity and calcium-dependent mechanisms maintain reliable inter-
for postulated the channel or channels altered for this venom. We neuron synaptic transmission in a rhythmic neural network. J Neurosci
do it a fast report for a possible mechanism for this venom and 2000;20:1754–66.
Robello M. Dependence of the conductance of the alpha-latrotoxin channel on applied
continued explored the effects of single peptides, for a biotechnol-
potential and potassium concentration. Biochim Biophys Acta 1989;978:
ogy development. 179–84.
Romero F, Altieri E, Urrutia M, Jara J. Venom of Latrodectus mactans from Chile (Araneae,
Theridiidae): effect on smooth muscle. Rev Biol Trop 2003;51:305–12.
Acknowledgments
Romero F, Cunha MA, Sanchez R, Ferreira AT, Schor N, Oshiro ME. Effects of arachno-
toxin on intracellular pH and calcium in human spermatozoa. Fertil Steril
We thank to Dr. Luis Aguayo, by the opportunity to use 2007;87:1345–9.
equipment and expertise to perform these studies Sanborn BM. Relationship of ion channel activity to control of myometrial calcium. J
Soc Gynecol Invest 2000;7:4–11.
F.R. and J.P. were supported by the Fondef-Conicyt Chile No. Scheer H, Madeddu L, Wanke E, Ferroni A, Meldolesi J. ‘‘Pure’’ presynaptic stimulatory
DO5I10416. toxins and ion transport. Regul Pept Suppl 1985;4:53–8.
Please cite this article in press as: Parodi J, Romero F. Synaptic effects of low molecular weight components from Chilean Black Widow
spider venom, Neurotoxicology (2008), doi:10.1016/j.neuro.2008.08.006

6. G Model
NEUTOX-899; No of Pages 6
6 J. Parodi, F. Romero / NeuroToxicology xxx (2008) xxx–xxx
Schenone H, Correa LE. Some practical knowledge of the biology of the spider Varghese A, Tenbroek EM, Coles J Jr, Sigg DC. Endogenous channels in HEK cells and
Latrodectus mactans and the latrodectism syndrome in Chile. Bol Chil Parasitol potential roles in HCN ionic current measurements. Prog Biophys Mol Biol
1985;40:18–23. 2006;90:26–37.
Schwartzkroin PA, Prince DA. Effects of TEA on hippocampal neurons. Brain Res Woodson PB, Schlapfer WT, Barondes SH. Amplitude and rate of decay of post-tetanic
1980;185:169–81. potentiation are controlled by different mechanisms. Brain Res 1978;157:
Shimuta SI, Nouailhetas VL, Valero VB, Paiva AC, Paiva TB. Effect of sodium concentra- 33–46.
tion and of atropine on the contractile response of the guinea-pig ileum to Yuan LL, Chen X. Diversity of potassium channels in neuronal dendrites. Prog Neurobiol
¨
potassium ions. Pflugers Arch 1982;394:186–90. 2006;78:374–89.
Please cite this article in press as: Parodi J, Romero F. Synaptic effects of low molecular weight components from Chilean Black Widow
spider venom, Neurotoxicology (2008), doi:10.1016/j.neuro.2008.08.006