DYNAMICS OF CENTRAL AND PERIPHERAL NERVOUS SYSTEM INTERACTION AFTER INJURY

The CNS and PNS form a single functional unit that is evident even under pathological conditions. After peripheral nerve injury, glial cells in the spinal cord are activated and can have both beneficial and detrimental effects on regeneration and functional recovery. The aim of the in vivo part of this study was to characterize the temporal and spatial dynamics of glial cell activation in the spinal cord after ventral caudal nerve transection in rats. Immunohistochemical analysis revealed a significant increase in the presence of microglia in the ipsilateral sacral spinal cord, indicating a pronounced and regionally specific inflammatory response. This microglial activity gradually decreased at later stages after injury. In contrast, no significant astrocytic response was detected at the analyzed time points, indicating a limited involvement of astrocytes in this injury model. The in vitro part investigated whether factors released from the spinal cord after peripheral nerve injury are able to modulate cellular responses in intact dissociated DRG cultures. Application of spinal cord-derived secretomes induced significant temporal and segmental-dependent changes in DRG cultures. At the glial level, the proportion of Iba1⁺ cells was modulated in a spatially specific manner. These changes were accompanied by a significant suppression of neuronal branching. Combined in vivo and in vitro findings demonstrate that peripheral nerve injury induces spatially and temporally organized cellular responses in the spinal cord, highlighting the close functional coupling between the CNS and PNS under pathological conditions.
The study was supported by APVV-23-0274, VEGA 2/0109/24 and VEGA 2/0120/23