Deltamethrin differentially affects neuronal subtypes in hippocampal primary culture

Abstract

The effects of deltamethrin on neuronal development and survival were studied using primary mouse hippocampal neurons in culture. Repeated applications of deltamethrin (between 2 nM and 2000 nM) decreased the number of neurons by 16–40%, respectively. Neuronal death was accompanied by an overall decrease of synaptic proteins. Deltamethrin treatment increased the K +-stimulated release of amino acid transmitters, GABA and glutamate. The release of the latter might also contribute to neuronal damage. A considerable number of neurons survived treatment with high concentrations of deltamethrin (200–2000 nM) and still displayed characteristics of mature neurons such as synaptic contacts or the expression of members of the Kv1 channel family. When analyzing subtypes of neurons calbindin- as well as somatostatin-positive neurons decreased by 50% after repeated treatment with 2 nM deltamethrin. Under the same conditions neuropeptide Y-positive neurons were up-regulated by 250%. Taken together these data show that deltamethrin at concentrations relevant in human toxicology differentially affects survival of neuronal subtypes by exerting either deleterious or supportive effects. We conclude that deltamethrin disturbs fine-tuning of neuronal efficiency in neuronal networks and might also interfere with the correct wiring during development.