Spinal cord injury imparis neurogenesis and induces glial reactivity in the hippocampus

JURE, I; PIETRANERA L; DE NICOLA, A; LABOMBARDA, FLORENCIA

NEUROCHEMICAL RESEARCH

SPRINGER/PLENUM PUBLISHERS

Lugar: New York; Año: 2017

0364-3190

Theincorporation of newborn neurons with increased synaptic remodeling andactivity-dependent plasticity in the dentate gyrus enhanceshippocampal-dependent learning performances. Astrocytes and microglial cellsare components of the neurogenic niche and regulate neurogenesis under normal andneurophatological conditions leading to functional consequences for learningand memory. Although cognitive impairments were reported in patients afterspinal cord injury (SCI), only few studies have considered remote changes inbrain structures which are not related with sensory and motor cortex. Thus, weexamined neurogenesis and glial reactivity by stereological assessment in dentategyrus sub-regions after three different intensities of thoracic spinal cordcompression in rats. Sixty days after injury we observed a decrease in the Basso-Bresnahan?Beattie locomotor scale scores,rotarod performance and volume of spare tissue that correlated with theseverity of the compression.  Regardingthe hippocampus, we observed that neurogenesis andhilar neurons were reduced after severe SCI, while only neurogenesis decreasedin the moderately injured group. In addition, severe SCI induced reactive microgliaand astrogliosis in all dentate gyrus sub-regions. Furthermore, the density ofreactive microglia increased in the hilus whereas astrogliosis developed in themolecular layer after moderate SCI. No changes were observed in the mildlyinjured rats. These results suggest glial response and neurogenesis are associatedwith injury intensity. Interestingly, hippocampal neurogenesis is moresensitive to SCI than astrocytes or microglia reaction, as moderate injuryimpairs the generation of new neurons without changing glial response in the subgranularzone.