Effects of lead exposure on dendrite and spine development in hippocampal dentate gyrus areas of rats

ABSTRACT Lead exposure has been implicated in the impairment of synaptic plasticity in the hippocampal dentate gyrus (DG) areas of rats. However, whether the degradation of physiological properties is based on the morphological alteration of granule neurons in DG areas remains elusive. Here, we examined the dendritic branch extension and spine formation of granule neurons after lead exposure during development in rats. Dendritic morphology was studied using Golgi‐Cox stain method, which was followed by Sholl analysis at postnatal days 14 and 21. Our results indicated that, for both ages, lead exposure significantly decreased the total dendritic length and spine density of granule neurons in the DG of the rat hippocampus. Further branch order analysis revealed that the decrease of dendritic length was observed only at the second branch order. Moreover, there were obvious deficits in the proportion and size of mushroom‐type spines. These deficits in spine formation and maturity were accompanied by a decrease in Arc/Arg3.1 expression. Our present findings are the first to show that developmental lead exposure disturbs branch and spine formation in hippocampal DG areas. Arc/Arg3.1 may have a critical role in the disruption of neuronal morphology and synaptic plasticity in lead‐exposed rats. Synapse 70:87–97, 2016. © 2016 Wiley Periodicals, Inc. Lead exposure during pregnancy and lactation disturbed the dendrite extension, spine protrusion and maturity of granule neurons in the hippocampal DG areas of rats. A decrease in Arc/Arg 3.1 expression may be involved in this effect.