Dendritic Morphology Analysis in Cortical Neurons of Mice Affected by Congenital Zika Virus Syndrome

Zika virus (ZIKV) is an arbovirus capable of infecting pregnant women and crossing the placental barrier, potentially compromising embryonic nervous system development. In animal models, infections during the gestational period have been observed to alter the profile of microglial activity, promoting excessive synaptic elimination and leading to cognitive dysfunctions. Thus, this study aims to analyze the dendritic morphology alterations of neurons in cortical regions affected by the virus. For this purpose,  Swiss mice were injected intraperitoneally with 100 PFU of ZIKV  isolated in Brazil or Mock solution. At ages P14 and P60, these animals were euthanized, and their brains were subjected to Golgi-Cox staining for fifteen days. By tridimensionally reconstructing pyramidal cortical neurons, a reduction of 48.9% in the total length of dendrites and 44.4% in the number of branching intersections was observed in infected animals when compared to control. The decrease in dendrite length and branching at younger ages may lead to compensation by generating a greater number of dendritic spines to provide a larger contact area with adjacent axons. To verify this hypothesis, a quantitative and qualitative analysis of dendritic spines from apical dendrites of pyramidal neurons from infragranular and supragranular layers of the motor cortex was performed. A reduction of 65,5% in the total number of spines was observed in both regions in the infected group at P60, but no difference was observed at P14. No significant differences in spine morphology were found between groups, but a larger sample and further analyses are needed. The results indicate that ZIKV infection promotes alterations in dendritic morphology and synaptic profile in infected animals, which may contribute to reported cognitive and motor dysfunctions associated with congenital Zika syndrome.