Brain-derived neurotrophic factor inhibits glucose intolerance after cerebral ischemia

PET Detection of Cerebral Necrosis Using an Infarct-Avid Agent 2-Deoxy-2-[18F]Fluoro-D-Glucaric Acid (FGA) in a Mouse Model of the Brain Stroke

PURPOSE

Ischemic stroke is a leading cause of disability worldwide. The volume of necrotic core in affected tissue plays a major role in selecting stroke patients for thrombolytic therapy or endovascular thrombectomy. In this study, we investigated a recently reported positron emission tomography (PET) agent 2-deoxy-2-[¹⁸F]fluoro-D-glucaric acid (FGA) to determine necrotic core in a model of transient middle cerebral artery occlusion (t-MCAO) in mice.

PROCEDURES

The radiopharmaceutical, FGA, was synthesized by controlled, rapid, and quantitative oxidation of clinical doses of 2-deoxy-2-[¹⁸F]fluoro-D-glucose (FDG) in a one-step reaction using a premade kit. Brain stroke was induced in the left cerebral hemisphere of CD-1 mice by occluding the middle cerebral artery for 1 h, and then allowing reperfusion by removing the occlusion. One day post-ictus, perfusion single-photon emission tomography (SPECT) was performed with ^99mTc-lableled hexamethylpropyleneamine oxime (HMPAO), followed by PET acquisition with FGA. Plasma and brain tissue homogenates were assayed for markers of inflammation and neurotrophins.

RESULTS

The kit-based synthesis was able to convert up to 2.2 GBq of FDG into FGA within 5 min. PET images showed 375 % more accumulation of FGA in the ipsilateral hemisphere than in the contralateral hemisphere. SPECT images showed that the ipsilateral HMPAO accumulation was reduced to 55 % of normal levels; there was a significant negative correlation between the ipsilateral accumulation of FGA and HMAPO (p < 0.05). FGA accumulation in stroke also correlated with IL-6 levels in the ipsilateral hemisphere. There was no change in IL-6 or TNFα in the plasma of stroke mice.

CONCLUSIONS

Accumulation of FGA correlated well with the perfusion defect and inflammatory injury. As a PET agent, FGA has potential to image infarcted core in the brain stroke injury with high sensitivity, resolution, and specificity.

Rehabilitation Training and Resveratrol Improve the Recovery of Neurological and Motor Function in Rats after Cerebral Ischemic Injury through the Sirt1 Signaling Pathway

This study was conducted to investigate the recovery of motor function in rats through the silent information regulator factor 2-related enzyme 1 (Sirt1) signal pathway-mediated rehabilitation training. Middle cerebral artery occlusion (MACO) was used to induce ischemia/reperfusion injury. The rats were subjected to no treatment (model), rehabilitation training (for 21 days), resveratrol (5 mg/kg for 21 days), and rehabilitation training plus resveratrol treatment. 24 h later, They were assessed for neurobehavioral score and motor behavior score and expression of brain derived-nerve neurotrophic factor (BDNF) and tyrosine kinase receptor B (TrkB). Compared with sham group, models had significantly higher neurobehavioral scores, balance beam, and rotary stick scores. Compared with the model group, rats in rehabilitation training and resveratrol groups had significantly reduced scores. Compared with rehabilitation training or resveratrol treatment alone, rehabilitation plus resveratrol further reduced the scores significantly. The percentage of cells expressing BDNF and TrkB and expression levels of BDNF and TrkB were similar between the model and sham groups, significantly increased in rehabilitation training and resveratrol groups, and further increased in rehabilitation training plus resveratrol group. These results indicate that rehabilitation raining plus resveratrol can significantly improve the recovery of motor function in rats after cerebral ischemic injury, which is likely related to the upregulation of the BDNF/TrkB signaling pathway.

Pharmacological approaches to intervention in hypomyelinating and demyelinating white matter pathology

White matter disease afflicts both developing and mature central nervous systems. Both cell intrinsic and extrinsic dysregulation result in profound changes in cell survival, axonal metabolism and functional performance. Experimental models of developmental white matter (WM) injury and demyelination have not only delineated mechanisms of signaling and inflammation, but have also paved the way for the discovery of pharmacological approaches to intervention. These reagents have been shown to enhance protection of the mature oligodendrocyte cell, accelerate progenitor cell recruitment and/or differentiation, or attenuate pathological stimuli arising from the inflammatory response to injury. Here we highlight reports of studies in the CNS in which compounds, namely peptides, hormones, and small molecule agonists/antagonists, have been used in experimental animal models of demyelination and neonatal brain injury that affect aspects of excitotoxicity, oligodendrocyte development and survival, and progenitor cell function, and which have been demonstrated to attenuate damage and improve WM protection in experimental models of injury. The molecular targets of these agents include growth factor and neurotransmitter receptors, morphogens and their signaling components, nuclear receptors, as well as the processes of iron transport and actin binding. By surveying the current evidence in non-immune targets of both the immature and mature WM, we aim to better understand pharmacological approaches modulating endogenous oligodendroglia that show potential for success in the contexts of developmental and adult WM pathology. This article is part of the Special Issue entitled 'Oligodendrocytes in Health and Disease'.