Pyramidal cell morphology and cell death in the hippocampus of adult mice with experimentally induced hydrocephalus

Abstract

Background: Hippo- campus is a neural structure in the temporal lobe that plays a crucial role in learning and mem- ory. Cognitive impairment with learning disabilities is a common feature in hydrocephalus and is more prominent in adult-onset hydrocephalus. The aim of this study is to describethe morpho- logical alterations in the pyrami- dal cells of the hippocampus of adult hydrocephalic mice. Method: Hydrocephalus was in- duced in adult albino mice by intra-cisternal injection of kaolin suspension (250 mg/ml in sterile water). They were sacrificed 7, 14 and 21 days post-induction. Mor- phological analysis was carried out on hematoxylin and eosin- stained coronal sections of the hippocampus: the pyramidal neu- rons (normal and pyknotic) in the CA1 and CA3 subregions were counted and the pyknotic index (PI) was calculated. The somatic and dendritic features of Golgi- stained pyramidal neurons were examined by light microscopy in both hydrocephalic and control mice. Result: The PI was significantly greater in the CA1 region of the hippocampus in the hydrocephalic groups compared to the age- matched controls. The dendritic processes of pyramidal neurons in the CA1 region were fewer with shorter terminal branches in the hydrocephalic mice than in con- trols; this was pronounced at 7 days post-induction. In the CA3 region, there was no difference in dendritic arborization between hydrocephalic and control mice. Conclusion: Acute adult-onset hydrocephalus was associated with increased pyknosis and reduced dendritic arborization in hippo- campal pyramidal cells in the CA1 but not CA3 region.

Keywords

• hippocampal pyrami- dal cell
• hydrocephalus
• pyknotic index
• golgi stain