Imaging increased metabolism in the spinal cord in mice after middle cerebral artery occlusion

Abstract

Emerging evidence indicates crosstalk between the brain and the hematopoietic system follow-ing cerebral ischemia. Here, we investigated metabolism and oxygenation in the spleen and spinal cord in a transient middle cerebral artery occlusion (tMCAO) mouse model that is wide-ly used in focal cerebral ischemia research. Naive, sham and tMCAO mice underwent positron emission tomography (PET) using [18F]fluorodeoxyglucose (FDG) for assessing glucose me-tabolism and multispectral optoacoustic tomography (MSOT) assisted with quantitative model-based reconstruction and unmixing algorithms for accurate mapping of oxygenation patterns in the peripheral tissues at 24 h after reperfusion. We found increased levels of [18F]FDG uptake and reduced MSOT oxygen saturation, indicating hypoxia in the thoracic spinal cord of tMCAO mice compared with sham-operated mice but not in the spleen. A positive correlation was observed between splenic and ipsilateral striatal [18F]FDG uptake. Reduced spleen size was observed in tMCAO mice compared with sham-operated mice ex vivo. tMCAO led to a significant increase in the numbers of mature T cells (CD4 and CD8) in femoral bone marrow tissues, concomitant with a stark reduction in these cell subsets in the spleen and their decrease in periph-eral blood. The numbers of mature granulocytes (determined as CD11b+Gr1hi cells) decreased in bone marrow tissues and blood but increased in the spleen. The combination of quantitative PET and MSOT thus enabled the observation of hypoxia and increased metabolic activity in the spinal cord of tMCAO mice at 24 h after occlusion compared to sham-operated mice.

Spinal cord perfusion impairments in the M83 mouse model of Parkinson’s disease

“…Optoacoustic imaging has previously been employed to study brain dynamics (Gottschalk et al 2019), hemodynamic alterations in neurodegenerative disease (Ni et al 2018) and stroke (Deán-Ben et al 2023), as well as other proteinopathies using extrinsic contract agents (Ni et al 2022; Straumann et al 2023; Vagenknecht et al 2022). This method has also been used to detect changes in the spinal cord of an ischemic stroke mouse model (Ni et al 2023), as well as in an experimental autoimmune encephalomyelitis (EAE) model of MS (Ramos-Vega et al 2022). To our knowledge, the current study is the first optoacoustic imaging study in PD mouse models.…”