Pyrethroid insecticides evoke neurotransmitter release from rabbit striatal slices

Area of Science:

• Neuroscience
• Toxicology
• Pharmacology

Background:

• Synthetic pyrethroids are widely used insecticides.
• Fenvalerate is a type II pyrethroid insecticide.
• Understanding insecticide neurotoxicity is crucial for public health.

Purpose of the Study:

• To investigate the effects of fenvalerate on neurotransmitter release in rabbit brain slices.
• To determine the mechanism of fenvalerate-induced neurotransmitter release.
• To explore regional differences in the brain's sensitivity to fenvalerate.

Main Methods:

• Rabbit brain slices (striatal and hippocampal) were used.
• Radioactive neurotransmitters ([3H]dopamine, [3H]acetylcholine, [3H]norepinephrine) were employed.
• Fenvalerate concentration-response and stereoisomer specificity were assessed.
• Effects of receptor activation (D2 dopamine) and channel blockers (tetrodotoxin) were examined.

Main Results:

• Fenvalerate induced a calcium-dependent, concentration-dependent release of [3H]dopamine and [3H]acetylcholine from striatal slices.
• This release was stereoisomer-specific, mediated by the toxic isomer.
• D2 dopamine receptor activation modulated the release, and tetrodotoxin blocked it.
• Fenvalerate did not affect [3H]norepinephrine or [3H]acetylcholine release in hippocampal slices.

Conclusions:

• Fenvalerate acts on voltage-dependent sodium channels in presynaptic membranes, causing depolarization.
• Neurotransmitter release (dopamine, acetylcholine) occurs via calcium-dependent exocytosis.
• Regional differences in pyrethroid neurotoxicity exist, with the striatum being more sensitive than the hippocampus.