Histomorphology and histomorphometry changes in the hippocampal regions of hydrocephalic adult rats induced using intracisternal kaolin suspension.

Background: Kaolin, an aluminum silicate usually injected intracisternally, induces hydrocephalus by causing an inflammatory reaction and fibrous scarring in the meninges; this leads to an obstruction of the cerebrospinal fluid (CSF) pathways, and ventricular enlargement ensues. Its effect on the histomorphometry of the hippocampus is yet to be fully explored; therefore this study aimed at assessing the histomorphology and histomorphometry changes in the hippocampus of hydrocephalic adult rats induced with sterile kaolin. Methods: Comminicating Hydrocephalus was induced intracisternally in adult rats, both sexes, using 0.04ml of 250mg/ml of kaolin (n=6), while the sham procedure was performed on controls (n=6), where a needle was introduced into their cisternal magna to mimic kaolin-induced hydrocephalus but no injection was performed. Rats were weighed weekly and then sacrificed on the fourth week via intracardiac perfusion to harvest the brain tissues. Harvested brains were processed for Cresyl violet-staining to assess neuronal damage. Data were analysed using GraphPad Prism 8 and ImageJ software. Results: In the quantitative analysis, the body weights of the rats induced with kaolin were significantly lower than those of the control rats (p<0.0001), while in the qualitative analysis, photomicrographs of Cresyl violet-stained hippocampal regions, CA1, CA3 and the Dentate Gyrus, showed a severely disorganized laminal cytoarchitecture of hydrocephalic rats compared to the control, and the pyknotic indices (PIs) of CA1, CA3 and the Dentate Gyrus of the 250mg/ml group were significantly higher than those of the control. Conclusion: Findings from this study showed that hydrocephalus altered the cytoarchitecture of the pyramidal neurons of the hippocampus of adult rats following intracisternal kaolin injection.