Immediate and Medium-term Changes in Cortical and Hippocampal Inhibitory Neuronal Populations after Diffuse TBI. (15th September 2018)

• Record Type: Journal Article
• Authors: Carron, Simone F.; Yan, Edwin B.; Allitt, Benjamin J.; Rajan, Ramesh
• Is Part Of: Neuroscience. Volume 388(2018)
• Page Start: 152
• Page End: 170
• Publication Date: 2018-09-15
• Subjects: CB calbindin -- CBP Calcium Binding Protein -- CR calretinin -- CCI controlled cortical impact -- dTBI diffuse traumatic brain injury -- LFPI lateral fluid percussion injury -- NPY neuropeptide Y -- PV parvalbumin -- SOM somatostatin -- SE status epilepticus -- TAI traumatic axonal injury -- TBI traumatic brain injury -- WDIA weight drop impact acceleration; diffuse traumatic brain injury -- neural injury -- interneurons -- inhibition -- cortex -- hippocampus -- time course; Neurochemistry -- Periodicals; Neurophysiology -- Periodicals; Neurology -- Periodicals; Neurochimie -- Périodiques; Neurophysiologie -- Périodiques; Neurochemistry; Neurophysiology; Electronic journals; Periodicals; Electronic journals; 612.8
• DOI: 10.1016/j.neuroscience.2018.07.020
• Languages: English
• ISSNs: 0306-4522

Abstract

Highlights: Time-dependent, brain area-specific changes in inhibition post diffuse TBI. Reduction in dendrite-targeting interneurons in cortex and hippocampus 24 h post TBI. Susceptibility of dendrite-targeting inhibitory neurons to diffuse TBI. Compensatory interneuronal changes 2 weeks post TBI in cortex and hippocampus. Abstract: Changes in inhibition following traumatic brain injury (TBI) appear to be one of the major factors that contribute to excitation:inhibition imbalance. Neuron pathology, interneurons in particular evolves from minutes to weeks post injury and follows a complex time course. Previously, we showed that in the long-term in diffuse TBI (dTBI), there was select reduction of specific dendrite-targeting neurons in sensory cortex and hippocampus while in motor cortex there was up-regulation of specific dendrite-targeting neurons. We now investigated the time course of dTBI effects on interneurons in neocortex and hippocampus. Brains were labeled with antibodies against calbindin (CB), parvalbumin (PV), calretinin (CR) neuropeptide Y (NPY), and somatostatin (SOM) at 24 h and 2 weeks post dTBI. We found time-dependent, brain area-specific changes in inhibition at 24 h and 2 weeks. At 24 h post-injury, reduction of dendrite-targeting inhibitory neurons occurred in sensory cortex and hippocampus. At 2 weeks, we found compensatory changes in the somatosensory cortex and CA2/3 of hippocampus affected at 24 h, with affected interneuronal populations returning to sham levels. However, DG of hippocampus now showed reduction of dendrite-targeting inhibitory neurons. Finally, with respect to motor cortex, there was an upregulation of dendrite-targeting interneurons in the supragranular layers at 24 h returning to normal levels by 2 weeks. Overall, our findings reconfirm that dendritic inhibition is particularly susceptible to brain trauma, but also show that there are complex brain-area-specific changes in inhibitory neuronal numbers and in compensatory changes, rather than a simple monotonic progression of changes post-dTBI.