Uninterrupted in vivo cerebral microdialysis measures of the acute neurochemical response to a single or repeated concussion in a rat model combining force and rotation

• Published in: Brain research Vol. 1838; p. 148998
• Main Authors: Massé, Ian, Moquin, Luc, Bouchard, Caroline, Gratton, Alain, De Beaumont, Louis
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 01.09.2024
• Subjects: Amino acids; Animals; Brain Concussion - metabolism; Cerebral microdialysis; Concussion; Disease Models, Animal; gamma-Aminobutyric Acid - metabolism; Glutamate; Glutamic Acid - metabolism; Glycine - metabolism; Head acceleration; Hippocampus - metabolism; Male; Microdialysis - methods; Neurochemical response; Rats; Rats, Sprague-Dawley; Taurine - metabolism; Amino acids; ECF; CNS; PFA; Head acceleration; ACSF; Glutamate; Neurochemical response; CA1; Cerebral microdialysis; Concussion; Ca2; MD; NMDA; GABA; TBI; mTBI
• DOI: 10.1016/j.brainres.2024.148998
• ISSN: 0006-8993; 1872-6240

[Display omitted] •Unveils acute neurochemical changes in concussions using microdialysis in rats.•Demonstrates significant glutamate and taurine increase after a single concussion.•Reveals less neurochemical changes, aggravated symptoms after repeated concussions.•Introduces a novel rat model combining force and rotation for concussion studies.•Suggests new insights into neurochemical dynamics after traumatic brain injuries. Altered extracellular amino acid concentrations following concussion or mild traumatic brain injury can result in delayed neuronal damage through overactivation of NMDA glutamatergic receptors. However, the consequences of repeated concussions prior to complete recovery are not well understood. In this study, we utilized in vivo cerebral microdialysis and a weight-drop model to investigate the acute neurochemical response to single and repeated concussions in adult rats that were fully conscious. A microdialysis probe was inserted into the hippocampus and remained in place during impact. Primary outcomes included concentrations of glutamate, GABA, taurine, glycine, glutamine, and serine, while secondary outcomes were righting times and excitotoxic indices. Compared to sham injury, the first concussion resulted in significant increases in glutamate, GABA, taurine, and glycine levels, longer righting times, and higher excitotoxic indices. Following the second concussion, righting times were significantly longer, suggesting cumulative effects of repeated concussion while only partial increases were observed in glutamate and taurine levels. GABA and glycine levels, and excitotoxic indices were comparable to sham injury. These findings suggest that single and repeated concussions may induce acute increases in several amino acids, while repeated concussions could exacerbate neurological symptoms despite less pronounced neurochemical changes.