Registration Dossier

Toxicological information

Neurotoxicity

Currently viewing:

Administrative data

Endpoint:
neurotoxicity
Remarks:
other: acute experiment in ganglion of mollusk
Type of information:
experimental study
Adequacy of study:
other information
Study period:
1998
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: no glp, no guideline, but well documented

Data source

Reference
Reference Type:
publication
Title:
Unnamed
Year:
2000
Report Date:
1998

Materials and methods

Test guideline
Qualifier:
no guideline available
Principles of method if other than guideline:
Methods
The effects of SnCl_2 and Sn8CH_3)_2 on the acetylcholine-activated currents were studied in
identified neurons of the pulmonate mollusk Lymnaea stagnalis, using a two microelectrode
membrane patential clamping method and intracellular dialysis in conditions of fixed potential
and ion concentrations.
Adult animals were colleceted in Lake Kish-Balaton and kept in aquarium at a temperature of
20-22°C. Experiments were conducted either on neurons in whole gaglion preperations or after
isolation of induvidula nerve cells.
Ganglia were prepared and identified neurons were isolated. Experiments using the two micro-
electrode membrane potential clamping technique, dissected ganglia were incubated in physiological
saline containing 0.1% protease for 5 min at room temperature. Connective tissue was then
removed and ganglia were washed in physiological saline and stored in the refigerator at 4°C
for 1 -2 h.
Experiments were performed using identified neurons RPcD1, VV12, VDC and RPaD1. Standard solution
contained 44mM NaCl, 1.7 mM KCl, 4 mM CaCl_2, 10 mM HEPES, pH 7.4. Solution for intracellular
dialysis consists of 43.5 mM KOH, 20 mM KCl, 10 mM EGTA, 2.5 mM HEPES, pH 7.3. This membrane
potential clamping method used a Dagan 8500 amplifier and an Axopatch-1D amplifier. Two
independent mircolecetrodes filled with 2.5 M potassium acetate and 25 mM KCl were insered in
neurons. Potential steps and data analyis were carried out using an A/D-D/A concerter card and
a standalone program. Chemical compounds were obtained from Sigma and Reanal. All experiments
were conduceted at room temperature (20-22°C). Acetylcholine was applied by mircoperfusion or
by replacing the whole solution for 12-16 sec with intervals 4-5 m in.
GLP compliance:
no
Limit test:
no

Test material

Reference
Name:
Unnamed
Type:
Constituent
Test material form:
solid - liquid: suspension
Details on test material:
-

Test animals

Species:
other: mollusk
Strain:
other: Lymnaea stagnalis
Sex:
not specified

Administration / exposure

Route of administration:
other: not relevant, see method
Vehicle:
other: not relevant, see method
Analytical verification of doses or concentrations:
not specified
Frequency of treatment:
see method
Doses / concentrations
Remarks:
Doses / Concentrations:
see method
Basis:
other: see method
No. of animals per sex per dose:
see method
Control animals:
yes

Results and discussion

Effect levels

Dose descriptor:
other: inhibition of sodium channels
Effect level:
25 other: µM
Based on:
test mat.
Sex:
not specified
Remarks on result:
other:

Any other information on results incl. tables

see publication

Applicant's summary and conclusion

Conclusions:
Sn+2 inhibits reversible the sodiom channels in ganglion
Executive summary:

In isolated single neurone or in whole ganglia preparation, SnCl2 caused a decrease in the acetylcholine-induced inward current in a dose-dependent way. Threshold concentration was 0.1 mkM and saturated at 5 mkM SnCl2. After 10-min. pre-treatment with SnCl2 the effect was more obvious (by 20%) than after 3-min pre-treatment. Sn(CH3)2 decreased the amplitude of Ach-induced current similarly to the inorganic Sn. The effect of Sn(CH3)2 was irreversible. The findings support earlier data that the agonist-activated channels are important targets for toxic metals. Direct action upon neuronal membrane seems to be an important event in modulation of synaptic transmission.