Late effect of developmental exposure to glycidol on hippocampal neurogenesis in mice: Loss of parvalbumin-expressing interneurons.

Developmental exposure to glycidol of rats causes axonal injury targeting axon terminals in dams and transient disruption of late-stage differentiation of hippocampal neurogenesis, accompanying sustained increase in the number of reelin-producing or calretinin-expressing interneurons in offspring. The molecular mechanism of disruptive neurogenesis probably targets the newly generating nerve terminals. We previously found differences between mice and rats in the effects on hippocampal neurogenesis after developmental exposure to the same neurotoxic substances. In the present study, we examined the effects and underlying mechanisms of developmental exposure to glycidol on hippocampal neurogenesis in mice. Glycidol (800 or 1600ppm) was administered in drinking water to mated female mice from gestational day 6 to postnatal day 21. Compared to mice drinking water without glycidol (control), the exposed dams showed axon terminal injury at both concentrations of glycidol. The offspring of the dams that had received 1600ppm glycidol had fewer parvalbumin (PVALB)+ γ-aminobutyric acid (GABA)-ergic interneurons and neuron-specific nuclear protein+ postmitotic neurons in the hilus of the hippocampal dentate gyrus. Thus, exposure of glycidol to adult mice induced axonal degeneration equivalent to that seen in the rat; however, the target mechanism for the disruption of hippocampal neurogenesis by developmental exposure was different from that in rats, with the hilar neuronal population not affected until adulthood. Considering the role of PVALB+ GABAergic interneurons in the brain, developmental glycidol exposure in mice may cause a decline in cognitive function in later life, and involve a different mechanism from that targeting axon terminals in rats.