Cellular lesions in the central nervous system of Periplaneta americana following insecticide treatment in vitro and in vivo. II. Glial cells.

Glial cell damage in the central nervous system of P. americana following insecticide treatment has been studied. Treatment of isolated metathoracic ganglia with 10 microM dieldrin caused an increase in the electron opacity of the inner and outer glial cells without effecting such a change in the structure of glial cells in the ventral connectives. Glial cells in the ganglia and ventral connectives treated with 5 microM bioresmethrin were found to be swollen and even more electron lucent than the control cells. In the prostrate cockroaches (24 hr after the treatment) the action of bioresmethrin and dieldrin upon peripheral glial cells was identical. Both insecticides caused vacuolation and darkening of outer glial cells; their effects extended to include glial cells in the ventral connectives. At the onset of poisoning, 20-30 min following the application of dieldrin, outer glial cells exhibited slight increase in electron opacity while the inner glial cells showed increase in lysosomal activity. The observed action of dieldrin upon the ultrastructure of glial cells was prevented by pretreatment of the nervous tissue with 10 mM Mg2+. Though tetrodotoxin and sodium-pentobarbital had very little effect upon the action of dieldrin, these drugs blocked bioresmethrin-induced alterations in the fine structure of glial cells. The results of this study suggest that alterations in the ultrastructure of insect neuroglia following treatment with insecticides tested in this study are probably due to perturbations in the neural element of the nervous system.